2273 lines
74 KiB
C
2273 lines
74 KiB
C
/*
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* Microsoft Confidential
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* Copyright (C) Microsoft Corporation 1992,1993,1994
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* All Rights Reserved.
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*
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* NFMCOMP.C -- memory-based compressor
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*
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* History:
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* 13-Feb-1994 msliger revised type names, ie, UINT16 -> UINT.
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* normalized MCI_MEMORY type.
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* 23-Feb-1994 msliger major scrub
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* 24-Feb-1994 msliger Changed MCI_MEMORY to MI_MEMORY.
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* 17-Mar-1994 msliger Updates for 32 bits.
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* 22-Mar-1994 msliger Changed interface USHORT -> UINT.
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* 06-Apr-1994 msliger Removed pack(1) for RISC; comp. bug avoided
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* 12-Apr-1994 msliger Removed 1's complement from stored blocks.
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* 12-May-1994 msliger ifdef'd 1's complement LARGE_STORED_BLOCKS.
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* 26-Sep-1994 msliger Conserve DGROUP size in DRVSPACE app:
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* Every pointer now explicitly FAR, and if
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* compiled with -DDRVSPACE, larger private
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* objects are created in far segments.
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* 29-Sep-1994 msliger Eliminated NFM_SIG from DRVSPACE use;
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* DRVSPACE has it's own signature. Cleaned
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* up function declarations, trying to avoid
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* "internal compiler errors".
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* 16-Apr-1996 msliger Endian-independent block signature.
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*/
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/* --- compilation options ------------------------------------------------ */
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/* define for messages if put_byte overflows output buffer */
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/* #define CK_DEBUG */
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/* --- commentary --------------------------------------------------------- */
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/*
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The "deflation" process depends on being able to identify portions
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of the input text which are identical to earlier input (within a
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sliding window trailing behind the input currently being processed).
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The most straightforward technique turns out to be the fastest for
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most input files: try all possible matches and select the longest.
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The key feature of this algorithm is that insertions into the string
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dictionary are very simple and thus fast, and deletions are avoided
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completely. Insertions are performed at each input character, whereas
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string matches are performed only when the previous match ends. So it
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is preferable to spend more time in matches to allow very fast string
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insertions and avoid deletions. The matching algorithm for small
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strings is inspired from that of Rabin & Karp. A brute force approach
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is used to find longer strings when a small match has been found.
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A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
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(by Leonid Broukhis).
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A previous version of this file used a more sophisticated algorithm
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(by Fiala and Greene) which is guaranteed to run in linear amortized
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time, but has a larger average cost, uses more memory and is patented.
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However the F&G algorithm may be faster for some highly redundant
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files if the parameter max_chain_length (described below) is too large.
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*/
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/* --- preprocessor ------------------------------------------------------- */
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#include <stdio.h>
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#include <setjmp.h>
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#include <string.h> /* for memcpy() */
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#include "nfmcomp.h"
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#pragma warning(disable:4001) /* no single-line comment balking */
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#ifndef _USHORT_DEFINED
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#define _USHORT_DEFINED
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typedef unsigned short USHORT;
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#endif
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#ifdef DRVSPACE
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#define FARBSS FAR /* put larger local objects outside DGROUP */
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#else
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#define FARBSS /* no effect to other users */
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#endif
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/* --- compression-related definitions ------------------------------------ */
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#define NFM_SIG0 'C' /* signature in a block = "CK" */
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#define NFM_SIG1 'K'
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#define NFM_SIG_LEN 2
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#ifndef WSIZE
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#define WSIZE 0x8000 /* window size--must be a power of two, and */
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#endif /* at least 32K for zip's deflate method */
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/* Tail of hash chains */
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#define NIL 0
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#ifdef LGM
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/* we're not hashing here, but we'll use these same defines so we don't */
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/* have to rewrite the entire program. */
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#define HASH_BITS 16 /* the two bytes */
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#define HASH_SIZE 256 /* table size for one-byte match heads */
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#else /* ifndef LGM: */
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#define HASH_BITS 15 /* hash index size in bits */
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#define HASH_SIZE (USHORT)(1 << HASH_BITS) /* # entries in hash table */
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#define HASH_MASK (HASH_SIZE-1) /* mask for indexing hash */
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#endif /* LGM */
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#define WMASK (WSIZE-1) /* mask for indexing window */
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/* The minimum and maximum match lengths */
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#define MIN_MATCH 3
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#define MAX_MATCH 258
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/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
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* It is easy to get rid of this optimization if necessary.
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*/
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#if (HASH_BITS < 8) || (MAX_MATCH != 258)
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error: Code too clever
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#endif
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/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
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#define TOO_FAR 4096
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#ifdef LGM
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#define REAL_MIN 2
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#else
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#define REAL_MIN (MIN_MATCH)
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#endif
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/* Minimum amount of lookahead, except at the end of the input file.
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* See deflate.c for comments about the MIN_MATCH+1.
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*/
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#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
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/* In order to simplify the code, particularly on 16 bit machines, match
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* distances are limited to MAX_DIST instead of WSIZE.
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*/
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#define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
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/* All codes must not exceed MAX_BITS bits */
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#define MAX_BITS 15
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/* Bit length codes must not exceed MAX_BL_BITS bits */
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#define MAX_BL_BITS 7
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/* number of length codes, not counting the special END_BLOCK code */
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#define LENGTH_CODES 29
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/* number of literal bytes 0..255 */
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#define LITERALS 256
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/* end of block literal code */
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#define END_BLOCK 256
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/* number of Literal or Length codes, including the END_BLOCK code */
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#define L_CODES (LITERALS+1+LENGTH_CODES)
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/* number of distance codes */
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#define D_CODES 30
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/* number of codes used to transfer the bit lengths */
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#define BL_CODES 19
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/* --- compressor definitions --------------------------------------------- */
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#ifdef CK_DEBUG
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#define put_byte(c) \
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{ \
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if (outcnt >= outsize) \
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{ \
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error("compressed buffer too small"); \
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} \
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else \
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{ \
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outbuf[outcnt++] = (BYTE) (c); \
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} \
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}
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#else
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#define put_byte(c) \
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{ \
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if (outcnt >= outsize) \
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{ \
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error(""); \
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} \
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else \
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{ \
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outbuf[outcnt++] = (BYTE) (c); \
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} \
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}
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#endif
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/* Output a 16 bit value, lsb first */
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#define put_short(w) \
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{ \
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if (outcnt < outsize-2) \
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{ \
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outbuf[outcnt++] = (BYTE) ((w) & 0xff); \
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outbuf[outcnt++] = (BYTE) ((USHORT)(w) >> 8); \
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} \
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else \
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{ \
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put_byte((BYTE) ((w) & 0xff)); \
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put_byte((BYTE) ((USHORT)(w) >> 8)); \
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} \
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}
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/*
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* Flush the current block, with given end-of-file flag.
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* IN assertion: strstart is set to the end of the current match.
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* Since we go from 32768 to 65536, strstart wraps around,
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* so have to check it if does
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*/
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#define FLUSH_BLOCK(eof) \
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flush_block( \
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(block_start >= 0L) ? \
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(char FAR *) &window[(USHORT) block_start] \
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: \
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NULL, \
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(strstart == 0) ? \
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(65536L - block_start) \
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: \
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(long) strstart - block_start, \
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(eof) \
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)
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/*
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* Update a hash value with the given input byte
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* IN assertion: all calls to to UPDATE_HASH are made with consecutive
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* input characters, so that a running hash key can be computed from the
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* previous key instead of complete recalculation each time.
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*/
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#ifndef LGM
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#define UPDATE_HASH(h,c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
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#endif
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/*
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* Insert string s in the dictionary and set match_head to the previous head
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* of the hash chain (the most recent string with same hash key). Return
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* the previous length of the hash chain.
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* IN assertion: all calls to to INSERT_STRING are made with consecutive
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* input characters and the first MIN_MATCH bytes of s are valid
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* (except for the last MIN_MATCH-1 bytes of the input file).
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*/
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#ifdef LGM
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#define INSERT_STRING(s, match_head) ins_str(s,&match_head)
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#else
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#define INSERT_STRING(s, match_head) \
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( \
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UPDATE_HASH(ins_h, window[(s) + REAL_MIN - 1]), \
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*(prev + ((s) & WMASK)) = match_head = *(head + ins_h), \
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*(head + ins_h) = (s) \
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)
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#endif
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/* Diagnostic functions */
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#ifdef DEBUG
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# define Assert(cond,msg) {if(!(cond)) error(msg);}
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# define Trace(x) fprintf x
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# define Tracev(x) {if (verbose) fprintf x ;}
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# define Tracevv(x) {if (verbose>1) fprintf x ;}
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# define Tracec(c,x) {if (verbose && (c)) fprintf x ;}
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# define Tracecv(c,x) {if (verbose>1 && (c)) fprintf x ;}
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#else
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# define Assert(cond,msg)
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# define Trace(x)
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# define Tracev(x)
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# define Tracevv(x)
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# define Tracec(c,x)
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# define Tracecv(c,x)
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#endif
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/* --- local data --------------------------------------------------------- */
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static BYTE FAR *l_buf; /* buffer for literals */
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static BYTE FAR *outbuf; /* output buffer */
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static USHORT FAR *d_buf; /* buffer for distances */
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static USHORT outcnt; /* bytes in output buffer */
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static UINT outsize; /* size of output buffer */
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#ifdef LGM
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static USHORT FAR *h1; /* one-byte match chains */
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static USHORT FAR *h2; /* two-byte match chains */
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#endif
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/* these initializations of pointers to the value 5 make them be in the */
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/* main data segment instead of the bss (uninitialized data) segment, */
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/* which is necessary for the asm code (match.asm). */
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static BYTE FAR * window= (BYTE FAR *) 5L; /* 2*WSIZE (iow, 64K) */
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static USHORT FAR * head= (USHORT FAR *) 5L; /* LGM: 1/2 K else: 128K */
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/* LGM: 256-entry lookup of the */
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/* head of each 1-byte chain */
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static USHORT FAR * prev= (USHORT FAR *) 5L; /* 64K */
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/* LGM: three-byte match chains */
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static int ins_h; /* hash index of string to be inserted */
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static int lookahead;
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static jmp_buf error_spot;
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/*
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* Local data used by the "bit string" routines.
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*/
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/* Output buffer. bits are inserted starting at the bottom (least significant
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* bits).
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*/
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static USHORT bi_buf;
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/* Number of bits used within bi_buf. (bi_buf might be implemented on
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* more than 16 bits on some systems.)
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*/
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#define Buf_size (8 * 2*(int)sizeof(char))
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/* Number of valid bits in bi_buf. All bits above the last valid bit
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* are always zero.
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*/
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static int bi_valid;
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#ifdef DEBUG
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ULONG bits_sent; /* bit length of the compressed data */
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#endif
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/* A Pos is an index in the character window. We use short instead of int to
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* save space in the various tables. IPos is used only for parameter passing.
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*/
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typedef USHORT Pos;
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typedef USHORT IPos;
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static ULONG window_size = 2L * WSIZE;
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static long block_start;
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/* window position at the beginning of the current output block. Gets
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* negative when the window is moved backwards.
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*/
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/* Number of bits by which ins_h and del_h must be shifted at each
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* input step. It must be such that after MIN_MATCH steps, the oldest
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* byte no longer takes part in the hash key, that is:
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* H_SHIFT * MIN_MATCH >= HASH_BITS
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*/
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#define H_SHIFT ((HASH_BITS + MIN_MATCH - 1) / MIN_MATCH)
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/* Length of the best match at previous step. Matches not greater than this
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* are discarded. This is used in the lazy match evaluation.
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*/
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static int prev_length;
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static USHORT strstart; /* start of string to insert */
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static USHORT match_start; /* start of matching string */
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/* To speed up deflation, hash chains are never searched beyond this length.
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* A higher limit improves compression ratio but degrades the speed.
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*/
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static USHORT max_chain_length = 4096;
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/* Attempt to find a better match only when the current match is strictly
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* smaller than this value.
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*/
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static int max_lazy_match = 32;
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/* Use a faster search when the previous match is longer than this */
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static int good_match = 258;
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/* Values for max_lazy_match, good_match and max_chain_length, depending on
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* the desired pack level (0..9). The values given below have been tuned to
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* exclude worst case performance for pathological files. Better values may be
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* found for specific files.
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*/
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/* Stop searching when current match exceeds this: */
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static int nice_match = 258;
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/* Note: the current code requires max_lazy >= MIN_MATCH and max_chain >= 4
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* but these restrictions can easily be removed at a small cost.
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*/
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/* result of memcmp for equal strings */
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#define EQUAL 0
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static int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
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= {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};
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static int extra_dbits[D_CODES] /* extra bits for each distance code */
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= {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
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static int extra_blbits[BL_CODES]/* extra bits for each bit length code */
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= {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};
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/* The three kinds of block type */
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#define STORED_BLOCK 0
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#define STATIC_TREES 1
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#define DYN_TREES 2
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/* comment about LIT_BUFSIZE and DIST_BUFSIZE */
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/* Sizes of match buffers for literals/lengths and distances. There are
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* 4 reasons for limiting LIT_BUFSIZE to 64K:
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* - frequencies can be kept in 16 bit counters
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* - if compression is not successful for the first block, all input data is
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* still in the window so we can still emit a stored block even when input
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* comes from standard input. (This can also be done for all blocks if
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* LIT_BUFSIZE is not greater than 32K.)
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* - if compression is not successful for a file smaller than 64K, we can
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* even emit a stored file instead of a stored block (saving 5 bytes).
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* - creating new Huffman trees less frequently may not provide fast
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* adaptation to changes in the input data statistics. (Take for
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* example a binary file with poorly compressible code followed by
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* a highly compressible string table.) Smaller buffer sizes give
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* fast adaptation but have of course the overhead of transmitting trees
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* more frequently.
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* - I can't count above 4
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* The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
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* memory at the expense of compression). Some optimizations would be possible
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* if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
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*/
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#define REP_3_6 16
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/* repeat previous bit length 3-6 times (2 bits of repeat count) */
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#define REPZ_3_10 17
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/* repeat a zero length 3-10 times (3 bits of repeat count) */
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#define REPZ_11_138 18
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/* repeat a zero length 11-138 times (7 bits of repeat count) */
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/*
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* Local data
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*/
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/* Data structure describing a single value and its code string. */
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typedef struct ct_data
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{
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union
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{
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USHORT freq; /* frequency count */
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USHORT code; /* bit string */
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} fc;
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union
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{
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USHORT dad; /* father node in Huffman tree */
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USHORT len; /* length of bit string */
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} dl;
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} ct_data;
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#define Freq fc.freq
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#define Code fc.code
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#define Dad dl.dad
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#define Len dl.len
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/* maximum heap size */
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#define HEAP_SIZE (2*L_CODES+1)
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static ct_data FARBSS dyn_ltree[HEAP_SIZE]; /* literal and length tree */
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static ct_data FARBSS dyn_dtree[2*D_CODES+1]; /* distance tree */
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/* The static literal tree. Since the bit lengths are imposed, there is no
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* need for the L_CODES extra codes used during heap construction. However
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* The codes 286 and 287 are needed to build a canonical tree (see ct_init
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* below).
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*/
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static ct_data FARBSS static_ltree[L_CODES+2];
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/* The static distance tree. (Actually a trivial tree since all codes use
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* 5 bits.)
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*/
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static ct_data FARBSS static_dtree[D_CODES];
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/* Huffman tree for the bit lengths */
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static ct_data FARBSS bl_tree[2*BL_CODES+1];
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typedef struct tree_desc
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{
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ct_data FAR *dyn_tree; /* the dynamic tree */
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ct_data FAR *static_tree; /* corresponding static tree or NULL */
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int FAR *extra_bits; /* extra bits for each code or NULL */
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int extra_base; /* base index for extra_bits */
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int elems; /* max number of elements in the tree */
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int max_length; /* max bit length for the codes */
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int max_code; /* largest code with non zero frequency */
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} tree_desc;
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static tree_desc l_desc =
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{
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dyn_ltree, static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS, 0
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};
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static tree_desc d_desc =
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{
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dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0
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};
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static tree_desc bl_desc =
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{
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bl_tree, (ct_data FAR *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS, 0
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};
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/* number of codes at each bit length for an optimal tree */
|
|
static USHORT FARBSS bl_count[MAX_BITS+1];
|
|
|
|
/* The lengths of the bit length codes are sent in order of decreasing
|
|
* probability, to avoid transmitting the lengths for unused bit length codes.
|
|
*/
|
|
static BYTE bl_order[BL_CODES]
|
|
= {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
|
|
|
|
/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
|
|
* The same heap array is used to build all trees.
|
|
*/
|
|
static int FARBSS heap[2*L_CODES+1]; /* heap used to build the Huffman trees */
|
|
static int heap_len; /* number of elements in the heap */
|
|
static int heap_max; /* element of largest frequency */
|
|
|
|
/* Depth of each subtree used as tie breaker for trees of equal frequency */
|
|
static BYTE FARBSS depth[2*L_CODES+1];
|
|
|
|
/* length code for each normalized match length (0 == MIN_MATCH) */
|
|
static BYTE FARBSS length_code[MAX_MATCH-MIN_MATCH+1];
|
|
|
|
/* distance codes. The first 256 values correspond to the distances
|
|
* 3 .. 258, the last 256 values correspond to the top 8 bits of
|
|
* the 15 bit distances.
|
|
*/
|
|
static BYTE FARBSS dist_code[512];
|
|
|
|
/* First normalized length for each code (0 = MIN_MATCH) */
|
|
static int FARBSS base_length[LENGTH_CODES];
|
|
|
|
/* First normalized distance for each code (0 = distance of 1) */
|
|
static int FARBSS base_dist[D_CODES];
|
|
|
|
/* flag_buf is a bit array distinguishing literals from lengths in
|
|
* l_buf, thus indicating the presence or absence of a distance.
|
|
*/
|
|
static BYTE FARBSS flag_buf[(LIT_BUFSIZE/8)];
|
|
|
|
static USHORT last_lit; /* running index in l_buf */
|
|
static USHORT last_dist; /* running index in d_buf */
|
|
static USHORT last_flags; /* running index in flag_buf */
|
|
static BYTE flags; /* current flags not yet saved in flag_buf */
|
|
static BYTE flag_bit; /* current bit used in flags */
|
|
/* bits are filled in flags starting at bit 0 (least significant).
|
|
* Note: these flags are overkill in the current code since we don't
|
|
* take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
|
|
*/
|
|
|
|
static ULONG opt_len; /* bit length of current block with optimal trees */
|
|
static ULONG static_len; /* bit length of current block with static trees */
|
|
|
|
static ULONG compressed_len; /* total bit length of compressed file */
|
|
|
|
#ifdef DEBUG
|
|
extern ULONG bits_sent; /* bit length of the compressed data */
|
|
#endif
|
|
|
|
/* Send a code of the given tree. c and tree must not have side effects */
|
|
|
|
#ifndef DEBUG
|
|
#define send_code(c, tree) send_bits(tree[c].Code, tree[c].Len)
|
|
#else /* DEBUG */
|
|
#define send_code(c, tree) \
|
|
{ if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \
|
|
send_bits(tree[c].Code, tree[c].Len); }
|
|
#endif
|
|
|
|
/* Mapping from a distance to a distance code. dist is the distance - 1 and
|
|
* must not have side effects. dist_code[256] and dist_code[257] are never
|
|
* used.
|
|
*/
|
|
#define d_code(dist) \
|
|
((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)])
|
|
|
|
/* the arguments must not have side effects */
|
|
#define MAX(a,b) (a >= b ? a : b)
|
|
|
|
/* --- local function prototypes ------------------------------------------ */
|
|
|
|
static void lm_init_clear_tables(void);
|
|
static void lm_init_use_tables(void);
|
|
static void lm_init(void);
|
|
static ULONG deflate(void);
|
|
static void ct_init(void);
|
|
static int ct_tally(int dist, int lc);
|
|
static ULONG flush_block(char FAR *buf, ULONG stored_len, int eof);
|
|
static void bi_init(void);
|
|
static void send_bits(int value, int length);
|
|
static USHORT bi_reverse(int value, int length);
|
|
static void bi_windup(void);
|
|
static void copy_block(char FAR *buf, USHORT len, int header);
|
|
|
|
#ifdef DEBUG
|
|
static void check_match(IPos start, IPos match, int length);
|
|
#else
|
|
#define check_match(start, match, length) /* as nothing */
|
|
#endif
|
|
|
|
static void init_block(void);
|
|
static void pqdownheap(ct_data FAR *tree, int k);
|
|
static void gen_bitlen(tree_desc FAR *desc);
|
|
static void gen_codes(ct_data FAR *tree, int max_code);
|
|
static void build_tree(tree_desc FAR *desc);
|
|
static void scan_tree(ct_data FAR *tree, int max_code);
|
|
static void send_tree(ct_data FAR *tree, int max_code);
|
|
static int build_bl_tree(void);
|
|
static void send_all_trees(int lcodes, int dcodes, int blcodes);
|
|
static void compress_block(ct_data FAR *ltree, ct_data FAR *dtree);
|
|
static void set_file_type(void);
|
|
static int longest_match(IPos cur_match);
|
|
|
|
#ifdef ASMV
|
|
extern void match_init(void); /* asm code initialization */
|
|
#endif
|
|
|
|
/* --- NFMcompress_init() ------------------------------------------------ */
|
|
|
|
int NFMcompress_init(void FAR *buf1,void FAR *buf2)
|
|
{
|
|
l_buf = buf1;
|
|
d_buf = buf2;
|
|
if (!l_buf || !d_buf)
|
|
return -1;
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
/* --- NFMcompress() ----------------------------------------------------- */
|
|
|
|
int NFMcompress(BYTE FAR *bfSrc, UINT cbSrc,
|
|
BYTE FAR *bfDest, UINT cbDest,
|
|
MI_MEMORY bfWrk1, MI_MEMORY bfWrk2,
|
|
#ifdef LGM
|
|
MI_MEMORY bfWrk3, MI_MEMORY bfWrk4,
|
|
#endif
|
|
char fhistory, UINT FAR *pcbDestRet)
|
|
{
|
|
#ifdef LGM
|
|
head = bfWrk1;
|
|
prev = bfWrk2;
|
|
h1 = bfWrk3;
|
|
h2 = bfWrk4;
|
|
#else
|
|
head = bfWrk2;
|
|
prev = bfWrk1;
|
|
#endif
|
|
|
|
outbuf = bfDest;
|
|
outcnt = 0;
|
|
outsize = cbDest;
|
|
|
|
window = bfSrc;
|
|
lookahead = cbSrc;
|
|
|
|
if (!fhistory)
|
|
{
|
|
#ifndef BIT16
|
|
memcpy(window+32768U,window,32768U);
|
|
#else
|
|
_fmemcpy(window+32768U,window,32768U);
|
|
#endif
|
|
}
|
|
|
|
bi_init();
|
|
ct_init();
|
|
lm_init();
|
|
|
|
if (fhistory)
|
|
{
|
|
lm_init_use_tables();
|
|
}
|
|
else
|
|
{
|
|
lm_init_clear_tables();
|
|
}
|
|
|
|
if (setjmp(error_spot) != 0)
|
|
{
|
|
return NFMinvalid;
|
|
}
|
|
|
|
#ifndef DRVSPACE
|
|
send_bits(NFM_SIG0,8); /* put in signature */
|
|
send_bits(NFM_SIG1,8);
|
|
|
|
*pcbDestRet = (USHORT) (NFM_SIG_LEN + deflate());
|
|
#else
|
|
*pcbDestRet = (USHORT) deflate();
|
|
#endif
|
|
|
|
if (fhistory)
|
|
{
|
|
#ifndef BIT16
|
|
memcpy(window,window+32768U,32768U);
|
|
#else
|
|
_fmemcpy(window,window+32768U,32768U);
|
|
#endif
|
|
}
|
|
|
|
return NFMsuccess;
|
|
}
|
|
|
|
/* --- error() ----------------------------------------------------------- */
|
|
|
|
static void error(char FAR *m)
|
|
{
|
|
#ifdef CK_DEBUG
|
|
printf("In error, got %s\n",m);
|
|
#else
|
|
m++; /* hush compiler */
|
|
#endif
|
|
|
|
longjmp(error_spot,-1);
|
|
}
|
|
|
|
/*
|
|
* PURPOSE
|
|
*
|
|
* Output variable-length bit strings. Compression can be done
|
|
* to a file or to memory. (The latter is not supported in this version.)
|
|
*
|
|
* DISCUSSION
|
|
*
|
|
* The PKZIP "deflate" file format interprets compressed file data
|
|
* as a sequence of bits. Multi-bit strings in the file may cross
|
|
* byte boundaries without restriction.
|
|
*
|
|
* The first bit of each byte is the low-order bit.
|
|
*
|
|
* The routines in this file allow a variable-length bit value to
|
|
* be output right-to-left (useful for literal values). For
|
|
* left-to-right output (useful for code strings from the tree routines),
|
|
* the bits must have been reversed first with bi_reverse().
|
|
*
|
|
* For in-memory compression, the compressed bit stream goes directly
|
|
* into the requested output buffer. The input data is read in blocks
|
|
* by the mem_read() function. The buffer is limited to 64K on 16 bit
|
|
* machines.
|
|
*
|
|
* INTERFACE
|
|
*
|
|
* void bi_init (FILE *zipfile)
|
|
* Initialize the bit string routines.
|
|
*
|
|
* void send_bits (int value, int length)
|
|
* Write out a bit string, taking the source bits right to
|
|
* left.
|
|
*
|
|
* int bi_reverse (int value, int length)
|
|
* Reverse the bits of a bit string, taking the source bits left to
|
|
* right and emitting them right to left.
|
|
*
|
|
* void bi_windup (void)
|
|
* Write out any remaining bits in an incomplete byte.
|
|
*
|
|
* void copy_block(char *buf, USHORT len, int header)
|
|
* Copy a stored block to the zip file, storing first the length and
|
|
* its one's complement if requested.
|
|
*
|
|
*/
|
|
|
|
/* --- bi_init() --------------------------------------------------------- */
|
|
|
|
/*
|
|
* Initialize the bit string routines.
|
|
*/
|
|
|
|
static void bi_init(void)
|
|
{
|
|
bi_buf = 0;
|
|
bi_valid = 0;
|
|
#ifdef DEBUG
|
|
bits_sent = 0L;
|
|
#endif
|
|
}
|
|
|
|
/* --- send_bits() ------------------------------------------------------- */
|
|
|
|
/*
|
|
* Send a value on a given number of bits.
|
|
* IN assertion: length <= 16 and value fits in length bits.
|
|
*/
|
|
|
|
static void send_bits(int value, int length)
|
|
{
|
|
#ifdef DEBUG
|
|
Tracev((stderr," l %2d v %4x ", length, value));
|
|
Assert(length > 0 && length <= 15, "invalid length");
|
|
bits_sent += (ULONG)length;
|
|
#endif
|
|
/* If not enough room in bi_buf, use (valid) bits from bi_buf and
|
|
* (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
|
|
* unused bits in value.
|
|
*/
|
|
if (bi_valid > Buf_size - length) {
|
|
bi_buf |= (value << bi_valid);
|
|
put_short(bi_buf);
|
|
bi_buf = (USHORT) (value >> (Buf_size - bi_valid));
|
|
bi_valid += length - Buf_size;
|
|
} else {
|
|
bi_buf |= value << bi_valid;
|
|
bi_valid += length;
|
|
}
|
|
}
|
|
|
|
/* --- bi_reverse() ------------------------------------------------------ */
|
|
|
|
/*
|
|
* Reverse the first len bits of a code, using straightforward code (a faster
|
|
* method would use a table)
|
|
* IN assertion: 1 <= len <= 15
|
|
*/
|
|
static USHORT bi_reverse(int code, int len)
|
|
/* USHORT code; the value to invert */
|
|
/* int len; its bit length */
|
|
{
|
|
register USHORT res = 0;
|
|
do {
|
|
res |= code & 1;
|
|
code >>= 1, res <<= 1;
|
|
} while (--len > 0);
|
|
return ((USHORT)(res >> 1));
|
|
}
|
|
|
|
/* --- bi_windup() ------------------------------------------------------- */
|
|
|
|
/*
|
|
* Write out any remaining bits in an incomplete byte.
|
|
*/
|
|
static void bi_windup(void)
|
|
{
|
|
if (bi_valid > 8) {
|
|
put_short(bi_buf);
|
|
} else if (bi_valid > 0) {
|
|
put_byte(bi_buf);
|
|
}
|
|
bi_buf = 0;
|
|
bi_valid = 0;
|
|
#ifdef DEBUG
|
|
bits_sent = (bits_sent+7) & ~7;
|
|
#endif
|
|
}
|
|
|
|
/* --- copy_block() ------------------------------------------------------ */
|
|
|
|
/*
|
|
* Copy a stored block to the zip file, storing first the length and its
|
|
* one's complement if requested.
|
|
*/
|
|
static void copy_block(char FAR *buf, USHORT len, int header)
|
|
/* char *buf; the input data */
|
|
/* USHORT len; its length */
|
|
/* int header; true if block header must be written */
|
|
{
|
|
bi_windup(); /* align on byte boundary */
|
|
|
|
if (header) {
|
|
put_short((USHORT)len);
|
|
#ifdef DEBUG
|
|
bits_sent += 16;
|
|
#endif
|
|
#ifdef LARGE_STORED_BLOCKS
|
|
put_short((USHORT)~len);
|
|
#ifdef DEBUG
|
|
bits_sent += 16;
|
|
#endif
|
|
#endif
|
|
}
|
|
#ifdef DEBUG
|
|
bits_sent += (ULONG)len<<3;
|
|
#endif
|
|
while (len--) {
|
|
put_byte(*buf++);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* PURPOSE
|
|
*
|
|
* Encode various sets of source values using variable-length
|
|
* binary code trees.
|
|
*
|
|
* DISCUSSION
|
|
*
|
|
* The PKZIP "deflation" process uses several Huffman trees. The more
|
|
* common source values are represented by shorter bit sequences.
|
|
*
|
|
* Each code tree is stored in the ZIP file in a compressed form
|
|
* which is itself a Huffman encoding of the lengths of
|
|
* all the code strings (in ascending order by source values).
|
|
* The actual code strings are reconstructed from the lengths in
|
|
* the UNZIP process, as described in the "application note"
|
|
* (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
|
|
*
|
|
* REFERENCES
|
|
*
|
|
* Lynch, Thomas J.
|
|
* Data Compression: Techniques and Applications, pp. 53-55.
|
|
* Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
|
|
*
|
|
* Storer, James A.
|
|
* Data Compression: Methods and Theory, pp. 49-50.
|
|
* Computer Science Press, 1988. ISBN 0-7167-8156-5.
|
|
*
|
|
* Sedgewick, R.
|
|
* Algorithms, p290.
|
|
* Addison-Wesley, 1983. ISBN 0-201-06672-6.
|
|
*
|
|
* INTERFACE
|
|
*
|
|
* void ct_init (USHORT *attr, int *methodp)
|
|
* Allocate the match buffer, initialize the various tables and save
|
|
* the location of the internal file attribute (ascii/binary) and
|
|
* method (DEFLATE/STORE)
|
|
*
|
|
* void ct_tally (int dist, int lc);
|
|
* Save the match info and tally the frequency counts.
|
|
*
|
|
* long flush_block (char *buf, ULONG stored_len, int eof)
|
|
* Determine the best encoding for the current block: dynamic trees,
|
|
* static trees or store, and output the encoded block to the zip
|
|
* file. Returns the total compressed length for the file so far.
|
|
*
|
|
*/
|
|
|
|
/*
|
|
* Allocate the match buffer, initialize the various tables and save the
|
|
* location of the internal file attribute (ascii/binary) and method
|
|
* (DEFLATE/STORE).
|
|
*/
|
|
static void ct_init(void)
|
|
{
|
|
int n; /* iterates over tree elements */
|
|
int bits; /* bit counter */
|
|
int length; /* length value */
|
|
int code; /* code value */
|
|
int dist; /* distance index */
|
|
|
|
compressed_len = 0L;
|
|
|
|
if (static_dtree[0].Len != 0) return; /* ct_init already called */
|
|
|
|
/* Initialize the mapping length (0..255) -> length code (0..28) */
|
|
length = 0;
|
|
for (code = 0; code < LENGTH_CODES-1; code++) {
|
|
base_length[code] = length;
|
|
for (n = 0; n < (1<<extra_lbits[code]); n++) {
|
|
length_code[length++] = (BYTE)code;
|
|
}
|
|
}
|
|
Assert (length == 256, "ct_init: length != 256");
|
|
/* Note that the length 255 (match length 258) can be represented
|
|
* in two different ways: code 284 + 5 bits or code 285, so we
|
|
* overwrite length_code[255] to use the best encoding:
|
|
*/
|
|
length_code[length-1] = (BYTE)code;
|
|
|
|
/* Initialize the mapping dist (0..32K) -> dist code (0..29) */
|
|
dist = 0;
|
|
for (code = 0 ; code < 16; code++) {
|
|
base_dist[code] = dist;
|
|
for (n = 0; n < (1<<extra_dbits[code]); n++) {
|
|
dist_code[dist++] = (BYTE)code;
|
|
}
|
|
}
|
|
Assert (dist == 256, "ct_init: dist != 256");
|
|
dist >>= 7; /* from now on, all distances are divided by 128 */
|
|
for ( ; code < D_CODES; code++) {
|
|
base_dist[code] = dist << 7;
|
|
for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) {
|
|
dist_code[256 + dist++] = (BYTE)code;
|
|
}
|
|
}
|
|
Assert (dist == 256, "ct_init: 256+dist != 512");
|
|
|
|
/* Construct the codes of the static literal tree */
|
|
for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
|
|
n = 0;
|
|
while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++;
|
|
while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++;
|
|
while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++;
|
|
while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++;
|
|
/* Codes 286 and 287 do not exist, but we must include them in the
|
|
* tree construction to get a canonical Huffman tree (longest code
|
|
* all ones)
|
|
*/
|
|
gen_codes((ct_data FAR *)static_ltree, L_CODES+1);
|
|
|
|
/* The static distance tree is trivial: */
|
|
for (n = 0; n < D_CODES; n++) {
|
|
static_dtree[n].Len = 5;
|
|
static_dtree[n].Code = bi_reverse(n, 5);
|
|
}
|
|
|
|
/* Initialize the first block of the first file: */
|
|
init_block();
|
|
}
|
|
|
|
/*
|
|
* Initialize a new block.
|
|
*/
|
|
static void init_block(void)
|
|
{
|
|
int n; /* iterates over tree elements */
|
|
|
|
/* Initialize the trees. */
|
|
for (n = 0; n < L_CODES; n++) dyn_ltree[n].Freq = 0;
|
|
for (n = 0; n < D_CODES; n++) dyn_dtree[n].Freq = 0;
|
|
for (n = 0; n < BL_CODES; n++) bl_tree[n].Freq = 0;
|
|
|
|
dyn_ltree[END_BLOCK].Freq = 1;
|
|
opt_len = static_len = 0L;
|
|
last_lit = last_dist = last_flags = 0;
|
|
flags = 0; flag_bit = 1;
|
|
}
|
|
|
|
#define SMALLEST 1
|
|
/* Index within the heap array of least frequent node in the Huffman tree */
|
|
|
|
|
|
/*
|
|
* Remove the smallest element from the heap and recreate the heap with
|
|
* one less element. Updates heap and heap_len.
|
|
*/
|
|
#define pqremove(tree, top) \
|
|
{\
|
|
top = heap[SMALLEST]; \
|
|
heap[SMALLEST] = heap[heap_len--]; \
|
|
pqdownheap(tree, SMALLEST); \
|
|
}
|
|
|
|
/*
|
|
* Compares to subtrees, using the tree depth as tie breaker when
|
|
* the subtrees have equal frequency. This minimizes the worst case length.
|
|
*/
|
|
#define smaller(tree, n, m) \
|
|
(tree[n].Freq < tree[m].Freq || \
|
|
(tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))
|
|
|
|
/*
|
|
* Restore the heap property by moving down the tree starting at node k,
|
|
* exchanging a node with the smallest of its two sons if necessary, stopping
|
|
* when the heap property is re-established (each father smaller than its
|
|
* two sons).
|
|
*/
|
|
static void pqdownheap(ct_data FAR *tree, int k)
|
|
/* ct_data *tree; the tree to restore */
|
|
/* int k; node to move down */
|
|
{
|
|
int v = heap[k];
|
|
int j = k << 1; /* left son of k */
|
|
while (j <= heap_len) {
|
|
/* Set j to the smallest of the two sons: */
|
|
if (j < heap_len && smaller(tree, heap[j+1], heap[j])) j++;
|
|
|
|
/* Exit if v is smaller than both sons */
|
|
if (smaller(tree, v, heap[j])) break;
|
|
|
|
/* Exchange v with the smallest son */
|
|
heap[k] = heap[j]; k = j;
|
|
|
|
/* And continue down the tree, setting j to the left son of k */
|
|
j <<= 1;
|
|
}
|
|
heap[k] = v;
|
|
}
|
|
|
|
/*
|
|
* Compute the optimal bit lengths for a tree and update the total bit length
|
|
* for the current block.
|
|
* IN assertion: the fields freq and dad are set, heap[heap_max] and
|
|
* above are the tree nodes sorted by increasing frequency.
|
|
* OUT assertions: the field len is set to the optimal bit length, the
|
|
* array bl_count contains the frequencies for each bit length.
|
|
* The length opt_len is updated; static_len is also updated if stree is
|
|
* not null.
|
|
*/
|
|
static void gen_bitlen(tree_desc FAR *desc)
|
|
/* tree_desc *desc; the tree descriptor */
|
|
{
|
|
ct_data FAR *tree = desc->dyn_tree;
|
|
int FAR *extra = desc->extra_bits;
|
|
int base = desc->extra_base;
|
|
int max_code = desc->max_code;
|
|
int max_length = desc->max_length;
|
|
ct_data FAR *stree = desc->static_tree;
|
|
int h; /* heap index */
|
|
int n, m; /* iterate over the tree elements */
|
|
int bits; /* bit length */
|
|
int xbits; /* extra bits */
|
|
USHORT f; /* frequency */
|
|
int overflow = 0; /* number of elements with bit length too large */
|
|
|
|
for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0;
|
|
|
|
/* In a first pass, compute the optimal bit lengths (which may
|
|
* overflow in the case of the bit length tree).
|
|
*/
|
|
tree[heap[heap_max]].Len = 0; /* root of the heap */
|
|
|
|
for (h = heap_max+1; h < HEAP_SIZE; h++) {
|
|
n = heap[h];
|
|
bits = tree[tree[n].Dad].Len + 1;
|
|
if (bits > max_length) bits = max_length, overflow++;
|
|
tree[n].Len = (USHORT)bits;
|
|
/* We overwrite tree[n].Dad which is no longer needed */
|
|
|
|
if (n > max_code) continue; /* not a leaf node */
|
|
|
|
bl_count[bits]++;
|
|
xbits = 0;
|
|
if (n >= base) xbits = extra[n-base];
|
|
f = tree[n].Freq;
|
|
opt_len += (ULONG)f * (bits + xbits);
|
|
if (stree) static_len += (ULONG)f * (stree[n].Len + xbits);
|
|
}
|
|
if (overflow == 0) return;
|
|
|
|
Trace((stderr,"\nbit length overflow\n"));
|
|
/* This happens for example on obj2 and pic of the Calgary corpus */
|
|
|
|
/* Find the first bit length which could increase: */
|
|
do {
|
|
bits = max_length-1;
|
|
while (bl_count[bits] == 0) bits--;
|
|
bl_count[bits]--; /* move one leaf down the tree */
|
|
bl_count[bits+1] += 2; /* move one overflow item as its brother */
|
|
bl_count[max_length]--;
|
|
/* The brother of the overflow item also moves one step up,
|
|
* but this does not affect bl_count[max_length]
|
|
*/
|
|
overflow -= 2;
|
|
} while (overflow > 0);
|
|
|
|
/* Now recompute all bit lengths, scanning in increasing frequency.
|
|
* h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
|
|
* lengths instead of fixing only the wrong ones. This idea is taken
|
|
* from 'ar' written by Haruhiko Okumura.)
|
|
*/
|
|
for (bits = max_length; bits != 0; bits--) {
|
|
n = bl_count[bits];
|
|
while (n != 0) {
|
|
m = heap[--h];
|
|
if (m > max_code) continue;
|
|
if (tree[m].Len != (USHORT) bits) {
|
|
Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
|
|
opt_len += ((long)bits-(long)tree[m].Len)*(long)tree[m].Freq;
|
|
tree[m].Len = (USHORT)bits;
|
|
}
|
|
n--;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Generate the codes for a given tree and bit counts (which need not be
|
|
* optimal).
|
|
* IN assertion: the array bl_count contains the bit length statistics for
|
|
* the given tree and the field len is set for all tree elements.
|
|
* OUT assertion: the field code is set for all tree elements of non
|
|
* zero code length.
|
|
*/
|
|
static void gen_codes(ct_data FAR *tree, int max_code)
|
|
/* ct_data *tree; the tree to decorate */
|
|
/* int max_code; largest code with non zero frequency */
|
|
{
|
|
USHORT next_code[MAX_BITS+1]; /* next code value for each bit length */
|
|
USHORT code = 0; /* running code value */
|
|
int bits; /* bit index */
|
|
int n; /* code index */
|
|
|
|
/* The distribution counts are first used to generate the code values
|
|
* without bit reversal.
|
|
*/
|
|
for (bits = 1; bits <= MAX_BITS; bits++) {
|
|
next_code[bits] = code = (USHORT)((code + bl_count[bits-1]) << 1);
|
|
}
|
|
/* Check that the bit counts in bl_count are consistent. The last code
|
|
* must be all ones.
|
|
*/
|
|
Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
|
|
"inconsistent bit counts");
|
|
Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
|
|
|
|
for (n = 0; n <= max_code; n++) {
|
|
int len = tree[n].Len;
|
|
if (len == 0) continue;
|
|
/* Now reverse the bits */
|
|
tree[n].Code = bi_reverse(next_code[len]++, len);
|
|
|
|
Tracec(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
|
|
n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Construct one Huffman tree and assigns the code bit strings and lengths.
|
|
* Update the total bit length for the current block.
|
|
* IN assertion: the field freq is set for all tree elements.
|
|
* OUT assertions: the fields len and code are set to the optimal bit length
|
|
* and corresponding code. The length opt_len is updated; static_len is
|
|
* also updated if stree is not null. The field max_code is set.
|
|
*/
|
|
static void build_tree(tree_desc FAR *desc)
|
|
/* tree_desc *desc; the tree descriptor */
|
|
{
|
|
ct_data FAR *tree = desc->dyn_tree;
|
|
ct_data FAR *stree = desc->static_tree;
|
|
int elems = desc->elems;
|
|
int n, m; /* iterate over heap elements */
|
|
int max_code = -1; /* largest code with non zero frequency */
|
|
int node = elems; /* next internal node of the tree */
|
|
|
|
/* Construct the initial heap, with least frequent element in
|
|
* heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
|
|
* heap[0] is not used.
|
|
*/
|
|
heap_len = 0, heap_max = HEAP_SIZE;
|
|
|
|
for (n = 0; n < elems; n++) {
|
|
if (tree[n].Freq != 0) {
|
|
heap[++heap_len] = max_code = n;
|
|
depth[n] = 0;
|
|
} else {
|
|
tree[n].Len = 0;
|
|
}
|
|
}
|
|
|
|
/* The pkzip format requires that at least one distance code exists,
|
|
* and that at least one bit should be sent even if there is only one
|
|
* possible code. So to avoid special checks later on we force at least
|
|
* two codes of non zero frequency.
|
|
*/
|
|
while (heap_len < 2) {
|
|
int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0);
|
|
tree[new].Freq = 1;
|
|
depth[new] = 0;
|
|
opt_len--; if (stree) static_len -= stree[new].Len;
|
|
/* new is 0 or 1 so it does not have extra bits */
|
|
}
|
|
desc->max_code = max_code;
|
|
|
|
/* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
|
|
* establish sub-heaps of increasing lengths:
|
|
*/
|
|
for (n = heap_len/2; n >= 1; n--) pqdownheap(tree, n);
|
|
|
|
/* Construct the Huffman tree by repeatedly combining the least two
|
|
* frequent nodes.
|
|
*/
|
|
do {
|
|
pqremove(tree, n); /* n = node of least frequency */
|
|
m = heap[SMALLEST]; /* m = node of next least frequency */
|
|
|
|
heap[--heap_max] = n; /* keep the nodes sorted by frequency */
|
|
heap[--heap_max] = m;
|
|
|
|
/* Create a new node father of n and m */
|
|
tree[node].Freq = (USHORT)(tree[n].Freq + tree[m].Freq);
|
|
depth[node] = (BYTE) (MAX(depth[n], depth[m]) + 1);
|
|
tree[n].Dad = tree[m].Dad = (USHORT)node;
|
|
#ifdef DUMP_BL_TREE
|
|
if (tree == bl_tree) {
|
|
fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
|
|
node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
|
|
}
|
|
#endif
|
|
/* and insert the new node in the heap */
|
|
heap[SMALLEST] = node++;
|
|
pqdownheap(tree, SMALLEST);
|
|
|
|
} while (heap_len >= 2);
|
|
|
|
heap[--heap_max] = heap[SMALLEST];
|
|
|
|
/* At this point, the fields freq and dad are set. We can now
|
|
* generate the bit lengths.
|
|
*/
|
|
gen_bitlen((tree_desc FAR *)desc);
|
|
|
|
/* The field len is now set, we can generate the bit codes */
|
|
gen_codes ((ct_data FAR *)tree, max_code);
|
|
}
|
|
|
|
/*
|
|
* Scan a literal or distance tree to determine the frequencies of the codes
|
|
* in the bit length tree. Updates opt_len to take into account the repeat
|
|
* counts. (The contribution of the bit length codes will be added later
|
|
* during the construction of bl_tree.)
|
|
*/
|
|
static void scan_tree(ct_data FAR *tree, int max_code)
|
|
/* ct_data *tree; the tree to be scanned */
|
|
/* int max_code; and its largest code of non zero frequency */
|
|
{
|
|
int n; /* iterates over all tree elements */
|
|
int prevlen = -1; /* last emitted length */
|
|
int curlen; /* length of current code */
|
|
int nextlen = tree[0].Len; /* length of next code */
|
|
int count = 0; /* repeat count of the current code */
|
|
int max_count = 7; /* max repeat count */
|
|
int min_count = 4; /* min repeat count */
|
|
|
|
if (nextlen == 0) max_count = 138, min_count = 3;
|
|
tree[max_code+1].Len = (USHORT)-1; /* guard */
|
|
|
|
for (n = 0; n <= max_code; n++) {
|
|
curlen = nextlen; nextlen = tree[n+1].Len;
|
|
if (++count < max_count && curlen == nextlen) {
|
|
continue;
|
|
} else if (count < min_count) {
|
|
bl_tree[curlen].Freq = (USHORT) (bl_tree[curlen].Freq + count);
|
|
} else if (curlen != 0) {
|
|
if (curlen != prevlen) bl_tree[curlen].Freq++;
|
|
bl_tree[REP_3_6].Freq++;
|
|
} else if (count <= 10) {
|
|
bl_tree[REPZ_3_10].Freq++;
|
|
} else {
|
|
bl_tree[REPZ_11_138].Freq++;
|
|
}
|
|
count = 0; prevlen = curlen;
|
|
if (nextlen == 0) {
|
|
max_count = 138, min_count = 3;
|
|
} else if (curlen == nextlen) {
|
|
max_count = 6, min_count = 3;
|
|
} else {
|
|
max_count = 7, min_count = 4;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Send a literal or distance tree in compressed form, using the codes in
|
|
* bl_tree.
|
|
*/
|
|
static void send_tree(ct_data FAR *tree, int max_code)
|
|
/* ct_data *tree; the tree to be scanned */
|
|
/* int max_code; and its largest code of non zero frequency */
|
|
{
|
|
int n; /* iterates over all tree elements */
|
|
int prevlen = -1; /* last emitted length */
|
|
int curlen; /* length of current code */
|
|
int nextlen = tree[0].Len; /* length of next code */
|
|
int count = 0; /* repeat count of the current code */
|
|
int max_count = 7; /* max repeat count */
|
|
int min_count = 4; /* min repeat count */
|
|
|
|
/* tree[max_code+1].Len = -1; */ /* guard already set */
|
|
if (nextlen == 0) max_count = 138, min_count = 3;
|
|
|
|
for (n = 0; n <= max_code; n++) {
|
|
curlen = nextlen; nextlen = tree[n+1].Len;
|
|
if (++count < max_count && curlen == nextlen) {
|
|
continue;
|
|
} else if (count < min_count) {
|
|
do { send_code(curlen, bl_tree); } while (--count != 0);
|
|
|
|
} else if (curlen != 0) {
|
|
if (curlen != prevlen) {
|
|
send_code(curlen, bl_tree); count--;
|
|
}
|
|
Assert(count >= 3 && count <= 6, " 3_6?");
|
|
send_code(REP_3_6, bl_tree); send_bits(count-3, 2);
|
|
|
|
} else if (count <= 10) {
|
|
send_code(REPZ_3_10, bl_tree); send_bits(count-3, 3);
|
|
|
|
} else {
|
|
send_code(REPZ_11_138, bl_tree); send_bits(count-11, 7);
|
|
}
|
|
count = 0; prevlen = curlen;
|
|
if (nextlen == 0) {
|
|
max_count = 138, min_count = 3;
|
|
} else if (curlen == nextlen) {
|
|
max_count = 6, min_count = 3;
|
|
} else {
|
|
max_count = 7, min_count = 4;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Construct the Huffman tree for the bit lengths and return the index in
|
|
* bl_order of the last bit length code to send.
|
|
*/
|
|
static int build_bl_tree(void)
|
|
{
|
|
int max_blindex; /* index of last bit length code of non zero freq */
|
|
|
|
/* Determine the bit length frequencies for literal and distance trees */
|
|
scan_tree((ct_data FAR *)dyn_ltree, l_desc.max_code);
|
|
scan_tree((ct_data FAR *)dyn_dtree, d_desc.max_code);
|
|
|
|
/* Build the bit length tree: */
|
|
build_tree((tree_desc FAR *)(&bl_desc));
|
|
/* opt_len now includes the length of the tree representations, except
|
|
* the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
|
|
*/
|
|
|
|
/* Determine the number of bit length codes to send. The pkzip format
|
|
* requires that at least 4 bit length codes be sent. (appnote.txt says
|
|
* 3 but the actual value used is 4.)
|
|
*/
|
|
for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
|
|
if (bl_tree[bl_order[max_blindex]].Len != 0) break;
|
|
}
|
|
/* Update opt_len to include the bit length tree and counts */
|
|
opt_len += 3*(max_blindex+1) + 5+5+4;
|
|
Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, static_len));
|
|
|
|
return max_blindex;
|
|
}
|
|
|
|
/*
|
|
* Send the header for a block using dynamic Huffman trees: the counts, the
|
|
* lengths of the bit length codes, the literal tree and the distance tree.
|
|
* IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
|
|
*/
|
|
static void send_all_trees(int lcodes, int dcodes, int blcodes)
|
|
/* int lcodes, dcodes, blcodes; number of codes for each tree */
|
|
{
|
|
int rank; /* index in bl_order */
|
|
|
|
Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
|
|
Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
|
|
"too many codes");
|
|
Tracev((stderr, "\nbl counts: "));
|
|
send_bits(lcodes-257, 5); /* not +255 as stated in appnote.txt */
|
|
send_bits(dcodes-1, 5);
|
|
send_bits(blcodes-4, 4); /* not -3 as stated in appnote.txt */
|
|
for (rank = 0; rank < blcodes; rank++) {
|
|
Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
|
|
send_bits(bl_tree[bl_order[rank]].Len, 3);
|
|
}
|
|
Tracev((stderr, "\nbl tree: sent %ld", bits_sent));
|
|
|
|
send_tree((ct_data FAR *)dyn_ltree, lcodes-1); /* send the literal tree */
|
|
Tracev((stderr, "\nlit tree: sent %ld", bits_sent));
|
|
|
|
send_tree((ct_data FAR *)dyn_dtree, dcodes-1); /* send the distance tree */
|
|
Tracev((stderr, "\ndist tree: sent %ld", bits_sent));
|
|
}
|
|
|
|
/*
|
|
* Determine the best encoding for the current block: dynamic trees, static
|
|
* trees or store, and output the encoded block to the zip file. This function
|
|
* returns the total compressed length for the file so far.
|
|
*/
|
|
static ULONG flush_block(char FAR *buf, ULONG stored_len, int eof)
|
|
/* char *buf; input block, or NULL if too old */
|
|
/* ULONG stored_len; length of input block */
|
|
/* int eof; true if this is the last block for a file */
|
|
{
|
|
ULONG opt_lenb, static_lenb; /* opt_len and static_len in bytes */
|
|
int max_blindex; /* index of last bit length code of non zero freq */
|
|
|
|
flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */
|
|
|
|
/* Construct the literal and distance trees */
|
|
build_tree((tree_desc FAR *)(&l_desc));
|
|
Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len));
|
|
|
|
build_tree((tree_desc FAR *)(&d_desc));
|
|
Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, static_len));
|
|
/* At this point, opt_len and static_len are the total bit lengths of
|
|
* the compressed block data, excluding the tree representations.
|
|
*/
|
|
|
|
/* Build the bit length tree for the above two trees, and get the index
|
|
* in bl_order of the last bit length code to send.
|
|
*/
|
|
max_blindex = build_bl_tree();
|
|
|
|
/* Determine the best encoding. Compute first the block length in bytes */
|
|
opt_lenb = (opt_len+3+7)>>3;
|
|
static_lenb = (static_len+3+7)>>3;
|
|
if (static_lenb <= opt_lenb)
|
|
{
|
|
opt_lenb = static_lenb;
|
|
}
|
|
|
|
#ifdef LARGE_STORED_BLOCKS
|
|
if ((stored_len+4 <= opt_lenb) && (buf != (char FAR *)0))
|
|
#else
|
|
if ((stored_len+2 <= opt_lenb) && (buf != (char FAR *)0))
|
|
#endif
|
|
{
|
|
/* 2 (4): one (two) word for the length */
|
|
/* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
|
|
* Otherwise we can't have processed more than WSIZE input bytes since
|
|
* the last block flush, because compression would have been
|
|
* successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
|
|
* transform a block into a stored block.
|
|
*/
|
|
send_bits((STORED_BLOCK<<1)+eof, 3); /* send block type */
|
|
compressed_len = (compressed_len + 3 + 7) & ~7L;
|
|
#ifdef LARGE_STORED_BLOCKS
|
|
compressed_len += (stored_len + 4) << 3;
|
|
#else
|
|
compressed_len += (stored_len + 2) << 3;
|
|
#endif
|
|
|
|
copy_block(buf, (USHORT)stored_len, 1); /* with header */
|
|
|
|
}
|
|
else if (static_lenb == opt_lenb)
|
|
{
|
|
send_bits((STATIC_TREES<<1)+eof, 3);
|
|
compress_block((ct_data FAR *)static_ltree,(ct_data FAR *)static_dtree);
|
|
compressed_len += 3 + static_len;
|
|
}
|
|
else
|
|
{
|
|
send_bits((DYN_TREES<<1)+eof, 3);
|
|
send_all_trees(l_desc.max_code+1, d_desc.max_code+1, max_blindex+1);
|
|
compress_block((ct_data FAR *)dyn_ltree, (ct_data FAR *)dyn_dtree);
|
|
compressed_len += 3 + opt_len;
|
|
}
|
|
Assert (compressed_len == bits_sent, "bad compressed size");
|
|
init_block();
|
|
|
|
if (eof)
|
|
{
|
|
bi_windup();
|
|
compressed_len += 7; /* align on byte boundary */
|
|
}
|
|
Tracev((stderr,"\ncomprlen %lu(%lu) ", compressed_len>>3,
|
|
compressed_len-7*eof));
|
|
|
|
return compressed_len >> 3;
|
|
}
|
|
|
|
/*
|
|
* Save the match info and tally the frequency counts. Return true if
|
|
* the current block must be flushed.
|
|
*/
|
|
static int ct_tally(int dist, int lc)
|
|
/* int dist; distance of matched string */
|
|
/* int lc; match length-MIN_MATCH or unmatched char (if dist==0) */
|
|
{
|
|
l_buf[last_lit++] = (BYTE)lc;
|
|
if (dist == 0) {
|
|
/* lc is the unmatched char */
|
|
dyn_ltree[lc].Freq++;
|
|
} else {
|
|
/* Here, lc is the match length - MIN_MATCH */
|
|
dist--; /* dist = match distance - 1 */
|
|
Assert((USHORT)dist < (USHORT)MAX_DIST &&
|
|
(USHORT)lc <= (USHORT)(MAX_MATCH-MIN_MATCH) &&
|
|
(USHORT)d_code(dist) < (USHORT)D_CODES, "ct_tally: bad match");
|
|
|
|
dyn_ltree[length_code[lc]+LITERALS+1].Freq++;
|
|
dyn_dtree[d_code(dist)].Freq++;
|
|
|
|
d_buf[last_dist++] = (USHORT)dist;
|
|
flags |= flag_bit;
|
|
}
|
|
flag_bit <<= 1;
|
|
|
|
/* Output the flags if they fill a byte: */
|
|
if ((last_lit & 7) == 0) {
|
|
flag_buf[last_flags++] = flags;
|
|
flags = 0, flag_bit = 1;
|
|
}
|
|
/* Try to guess if it is profitable to stop the current block here */
|
|
if ((last_lit & 0xfff) == 0) {
|
|
/* Compute an upper bound for the compressed length */
|
|
ULONG out_length = (ULONG)last_lit*8L;
|
|
ULONG in_length = (ULONG)strstart-block_start;
|
|
int dcode;
|
|
for (dcode = 0; dcode < D_CODES; dcode++) {
|
|
out_length += (ULONG)dyn_dtree[dcode].Freq*(5L+extra_dbits[dcode]);
|
|
}
|
|
out_length >>= 3;
|
|
Trace((stderr,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
|
|
last_lit, last_dist, in_length, out_length,
|
|
100L - out_length*100L/in_length));
|
|
if (last_dist < last_lit/2 && out_length < in_length/2) return 1;
|
|
}
|
|
return (last_lit == LIT_BUFSIZE-1 || last_dist == DIST_BUFSIZE);
|
|
/* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
|
|
* on 16 bit machines and because stored blocks are restricted to
|
|
* 64K-1 bytes.
|
|
*/
|
|
}
|
|
|
|
/* --- compress_block() --------------------------------------------------- */
|
|
|
|
/*
|
|
* Send the block data compressed using the given Huffman trees
|
|
*/
|
|
|
|
static void compress_block(ct_data FAR *ltree, ct_data FAR *dtree)
|
|
/* ct_data *ltree; literal tree */
|
|
/* ct_data *dtree; distance tree */
|
|
{
|
|
int dist; /* distance of matched string */
|
|
int lc; /* match length or unmatched char (if dist == 0) */
|
|
USHORT lx = 0; /* running index in l_buf */
|
|
USHORT dx = 0; /* running index in d_buf */
|
|
USHORT fx = 0; /* running index in flag_buf */
|
|
BYTE flag = 0; /* current flags */
|
|
int code; /* the code to send */
|
|
int extra; /* number of extra bits to send */
|
|
|
|
if (last_lit != 0)
|
|
{
|
|
do
|
|
{
|
|
if ((lx & 7) == 0)
|
|
{
|
|
flag = flag_buf[fx++];
|
|
}
|
|
|
|
lc = l_buf[lx++];
|
|
|
|
if ((flag & 1) == 0)
|
|
{
|
|
send_code(lc, ltree); /* send a literal byte */
|
|
Tracecv(isgraph(lc), (stderr," '%c' ", lc));
|
|
}
|
|
else
|
|
{
|
|
/* Here, lc is the match length - MIN_MATCH */
|
|
code = length_code[lc];
|
|
send_code(code+LITERALS+1, ltree); /* send the length code */
|
|
extra = extra_lbits[code];
|
|
|
|
if (extra != 0)
|
|
{
|
|
lc -= base_length[code];
|
|
send_bits(lc, extra); /* send the extra length bits */
|
|
}
|
|
|
|
/* Here, dist is the match distance - 1 */
|
|
dist = d_buf[dx++];
|
|
|
|
code = d_code(dist);
|
|
Assert (code < D_CODES, "bad d_code");
|
|
|
|
send_code(code, dtree); /* send the distance code */
|
|
extra = extra_dbits[code];
|
|
|
|
if (extra != 0)
|
|
{
|
|
dist -= base_dist[code];
|
|
send_bits(dist, extra); /* send the extra distance bits */
|
|
}
|
|
} /* literal or match pair ? */
|
|
|
|
flag >>= 1;
|
|
} while (lx < last_lit);
|
|
}
|
|
|
|
send_code(END_BLOCK, ltree);
|
|
}
|
|
|
|
/* --- ins_str() ---------------------------------------------------------- */
|
|
|
|
#ifdef LGM
|
|
/*** ins_str - Insert current string into search tables, find 3 byte match
|
|
*
|
|
* Entry:
|
|
* s - Index of string in input buffer to process (points to
|
|
* first character of string)
|
|
* match_head - Pointer to receive index of most recent previous
|
|
* 3 byte match (if any)
|
|
* Globals
|
|
* -------
|
|
* head[] - 256 entry array, indexed by the first byte of a string,
|
|
* that points into the array h1[]. head[] records the
|
|
* start of the linked lists of 1-byte matches.
|
|
*
|
|
* h1[] - Chains together 1-byte matches. For example, if head['a']
|
|
* is 203, then 'a' appears at position 203 in the input
|
|
* buffer, and h1[203] is next previous position in the input
|
|
* buffer than contained an 'a'.
|
|
*
|
|
* h2[] - Chains together 2-byte matches. For example, if the current
|
|
* input string is 'ab', and we looked up in head[] and followed
|
|
* the h1[] link for 'a' until we found a previous occurence of
|
|
* 'ab' in the input at position 119, then h2[119] will point
|
|
* to the *next* previous position in the input that contained
|
|
* the string 'ab'.
|
|
*
|
|
* prev[] - Chains together 3 byte matches. Following the same scheme
|
|
* as h1[] and h2[] above, if the string 'abc' is at position
|
|
* 382 in the input buffer, then prev[382] contains the next
|
|
* previous position in the input buffer where the string 'abc'
|
|
* was seen.
|
|
*
|
|
* Exit-Success:
|
|
* *match_head = valid index in input buffer previous string;
|
|
* Search tables updated for this string;
|
|
*
|
|
* Exit-Failure:
|
|
* *match_head = NIL, no previous 3 byte match found.
|
|
* Search tables updated for this string;
|
|
*/
|
|
static void ins_str(USHORT s, IPos FAR *match_head)
|
|
{
|
|
IPos i;
|
|
BYTE b2, b3;
|
|
IPos limit = (IPos) (strstart > (IPos)MAX_DIST ?
|
|
strstart - (IPos)MAX_DIST : NIL);
|
|
USHORT chain_length = max_chain_length; /* max hash chain length */
|
|
|
|
ins_h = (USHORT)window[s]; /* ins_h = index of this char */
|
|
|
|
/** Update head of 1-byte chain and link in this byte **/
|
|
|
|
i = *(head+ins_h); /* i = previous occurance of this char */
|
|
*(head+ins_h) = s; /* head[ins_h] = this occurance */
|
|
|
|
*(h1+(s & WMASK)) = i; /* maintain single char chain */
|
|
|
|
/* Follow single char chain looking for a two char match */
|
|
|
|
b2 = window[s+1]; /* b2 = 2nd char in string */
|
|
while (i != NIL && b2 != window[i+1]) {
|
|
i = *(h1+(i & WMASK));
|
|
if (i <= limit || --chain_length == 0)
|
|
i = NIL;
|
|
}
|
|
|
|
*(h2+(s & WMASK)) = i; /* maintain two char chain */
|
|
|
|
/* Follow two char chain looking for a three char match */
|
|
|
|
b3 = window[s+2]; /* b3 = 3rd char in string */
|
|
while (i != NIL && b3 != window[i+2]) {
|
|
i = *(h2+(i & WMASK));
|
|
if (i <= limit || --chain_length == 0)
|
|
i = NIL;
|
|
}
|
|
|
|
*(prev+(s & WMASK)) = i; /* maintain three char chain */
|
|
|
|
*match_head = i; /* return prior three char occurance */
|
|
/* (or NIL if none) */
|
|
}
|
|
#endif /* LGM */
|
|
|
|
/* --- lm_init_clear_tables() --------------------------------------------- */
|
|
|
|
/*
|
|
* Initialize the "longest match" routines
|
|
*/
|
|
static void lm_init_clear_tables(void) /* clear out the hash tables */
|
|
{
|
|
Pos j;
|
|
|
|
/* Initialize the hash table. */
|
|
|
|
for (j = 0; j < HASH_SIZE; j++)
|
|
{
|
|
*(head+j) = NIL;
|
|
}
|
|
|
|
/* prev will be initialized on the fly */
|
|
}
|
|
|
|
/* --- lm_init_use_tables() ----------------------------------------------- */
|
|
|
|
/* clear out the hash tables of 2 times ago junk */
|
|
|
|
static void lm_init_use_tables(void)
|
|
{
|
|
Pos n,m;
|
|
|
|
for (n = 0; n < HASH_SIZE; n++)
|
|
{
|
|
m = *(head+n);
|
|
*(head+n) = (Pos)((m >= WSIZE) ? (m - WSIZE) : NIL);
|
|
}
|
|
|
|
for (n = 0; n < WSIZE; n++)
|
|
{
|
|
m = *(prev+n);
|
|
*(prev+n) = (Pos)((m >= WSIZE) ? (m - WSIZE) : NIL);
|
|
|
|
/* If n is not on any hash chain, prev[n] is garbage but
|
|
* its value will never be used.
|
|
*/
|
|
|
|
#ifdef LGM
|
|
m = *(h1+n);
|
|
*(h1+n) = (Pos)((m >= WSIZE) ? (m - WSIZE) : NIL);
|
|
|
|
m = *(h2+n);
|
|
*(h2+n) = (Pos)((m >= WSIZE) ? (m - WSIZE) : NIL);
|
|
#endif
|
|
}
|
|
}
|
|
|
|
/* --- lm_init() ---------------------------------------------------------- */
|
|
|
|
static void lm_init(void)
|
|
{
|
|
#ifndef LGM
|
|
USHORT j;
|
|
#endif
|
|
|
|
strstart = 32768U;
|
|
block_start = 32768L;
|
|
|
|
/* lookahead already set */
|
|
|
|
#ifdef ASMV
|
|
match_init(); /* asm code initialization */
|
|
#endif
|
|
|
|
ins_h = 0;
|
|
|
|
#ifndef LGM
|
|
for (j = 0; j < (REAL_MIN - 1); j++)
|
|
{
|
|
UPDATE_HASH(ins_h, window[j + strstart]);
|
|
}
|
|
|
|
/* If lookahead < MIN_MATCH, ins_h is garbage, but this is
|
|
* not important since only literal bytes will be emitted.
|
|
*/
|
|
#endif
|
|
}
|
|
|
|
/* --- longest_match() ---------------------------------------------------- */
|
|
|
|
/*
|
|
* Set match_start to the longest match starting at the given string and
|
|
* return its length. Matches shorter or equal to prev_length are discarded,
|
|
* in which case the result is equal to prev_length and match_start is
|
|
* garbage.
|
|
* IN assertions: cur_match is the head of the hash chain for the current
|
|
* string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
|
|
*/
|
|
|
|
/* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
|
|
* match.s. The code is functionally equivalent, so you can use the C version
|
|
* if desired.
|
|
*/
|
|
#ifndef ASMV
|
|
static int longest_match(IPos cur_match)
|
|
{
|
|
USHORT chain_length = max_chain_length; /* max hash chain length */
|
|
register BYTE FAR *scan = window + strstart; /* current string */
|
|
register BYTE FAR *match; /* matched string */
|
|
register int len; /* length of current match */
|
|
int best_len = prev_length; /* best match length so far */
|
|
IPos limit;
|
|
|
|
#ifdef UNALIGNED_OK
|
|
/* Compare two bytes at a time. Note: this is not always beneficial.
|
|
* Try with and without -DUNALIGNED_OK to check.
|
|
*/
|
|
register BYTE FAR *strend = window + strstart + MAX_MATCH - 1;
|
|
register USHORT scan_start = *(USHORT FAR *)scan;
|
|
register USHORT scan_end = *(USHORT FAR *)(scan + best_len - 1);
|
|
#else
|
|
register BYTE FAR *strend = window + strstart + MAX_MATCH;
|
|
register BYTE scan_end1 = scan[best_len - 1];
|
|
register BYTE scan_end = scan[best_len];
|
|
#endif
|
|
|
|
/* Stop when cur_match becomes <= limit. To simplify the code,
|
|
* we prevent matches with the string of window index 0.
|
|
*/
|
|
|
|
if (strstart > (IPos)MAX_DIST)
|
|
{
|
|
limit = (IPos)(strstart - MAX_DIST);
|
|
}
|
|
else
|
|
{
|
|
limit = NIL;
|
|
}
|
|
|
|
//BUGBUG 01-Mar-1994 msliger What's this doing?
|
|
/* Do not waste too much time if we already have a good match: */
|
|
if (prev_length >= good_match)
|
|
{
|
|
chain_length >>= 2;
|
|
}
|
|
|
|
Assert(strstart <= window_size-MIN_LOOKAHEAD, "insufficient lookahead");
|
|
|
|
do
|
|
{
|
|
Assert(cur_match < strstart, "no future");
|
|
match = window + cur_match;
|
|
|
|
/* Skip to next match if the match length cannot increase
|
|
* or if the match length is less than 2:
|
|
*/
|
|
|
|
#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
|
|
|
|
/* This code assumes sizeof(USHORT) == 2. Do not use
|
|
* UNALIGNED_OK if your compiler uses a different size.
|
|
*/
|
|
|
|
if ((*(USHORT FAR *)(match + best_len - 1) != scan_end) ||
|
|
**(USHORT FAR *)match != scan_start))
|
|
{
|
|
continue;
|
|
}
|
|
|
|
/* It is not necessary to compare scan[2] and match[2] since they are
|
|
* always equal when the other bytes match, given that the hash keys
|
|
* are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
|
|
* strstart+3, +5, ... up to strstart+257. We check for insufficient
|
|
* lookahead only every 4th comparison; the 128th check will be made
|
|
* at strstart+257. If (MAX_MATCH - 2) is not a multiple of 8, it is
|
|
* necessary to put more guard bytes at the end of the window, or
|
|
* to check more often for insufficient lookahead.
|
|
*/
|
|
scan++;
|
|
match++;
|
|
|
|
do
|
|
{
|
|
} while ((*(USHORT FAR *)(scan += 2) == *(USHORT FAR *)(match += 2)) &&
|
|
(*(USHORT FAR *)(scan += 2) == *(USHORT FAR *)(match += 2)) &&
|
|
(*(USHORT FAR *)(scan += 2) == *(USHORT FAR *)(match += 2)) &&
|
|
(*(USHORT FAR *)(scan += 2) == *(USHORT FAR *)(match += 2)) &&
|
|
(scan < strend));
|
|
|
|
/* Here, scan <= window+strstart+257 */
|
|
|
|
Assert(scan <= window+(USHORT)(window_size-1), "wild scan");
|
|
|
|
if (*scan == *match)
|
|
{
|
|
scan++;
|
|
}
|
|
|
|
len = (USHORT) (scan - strend + (MAX_MATCH-1));
|
|
scan = strend - (MAX_MATCH-1);
|
|
|
|
#else /* UNALIGNED_OK */
|
|
|
|
if ((match[best_len] != scan_end) ||
|
|
(match[best_len-1] != scan_end1) || (*match != *scan) ||
|
|
(*++match != scan[1]) || (*++match != scan[2]))
|
|
{
|
|
continue;
|
|
}
|
|
|
|
/* The check at best_len-1 can be removed because it will be made
|
|
* again later. (This heuristic is not always a win.)
|
|
* It is not necessary to compare scan[2] and match[2] since they
|
|
* are always equal when the other bytes match, given that
|
|
* the hash keys are equal and that HASH_BITS >= 8.
|
|
*/
|
|
|
|
/* duh you idiot whoever wrote this code. MIN_MATCH is a defined */
|
|
/* constant that can be changed, but if you do it breaks THIS */
|
|
/* shitty code. So now hack away using REAL_MIN. */
|
|
|
|
scan += MIN_MATCH - 1;
|
|
|
|
/* We check for insufficient lookahead only every 8th comparison;
|
|
* the 256th check will be made at strstart+258.
|
|
*/
|
|
|
|
do
|
|
{
|
|
} while ((*++scan == *++match && *++scan == *++match) &&
|
|
(*++scan == *++match && *++scan == *++match) &&
|
|
(*++scan == *++match && *++scan == *++match) &&
|
|
(*++scan == *++match && *++scan == *++match) &&
|
|
(scan < strend));
|
|
|
|
len = scan - strend + MAX_MATCH;
|
|
|
|
scan = strend - MAX_MATCH;
|
|
|
|
#endif /* UNALIGNED_OK */
|
|
|
|
if (len > best_len)
|
|
{
|
|
match_start = cur_match;
|
|
best_len = len;
|
|
|
|
if (len >= nice_match)
|
|
{
|
|
break;
|
|
}
|
|
|
|
#ifdef UNALIGNED_OK
|
|
scan_end = *(USHORT FAR *)(scan + best_len - 1);
|
|
#else
|
|
scan_end1 = scan[best_len - 1];
|
|
scan_end = scan[best_len];
|
|
#endif
|
|
}
|
|
} while (((cur_match = *(prev+(cur_match & WMASK))) > limit) &&
|
|
(--chain_length != 0));
|
|
|
|
/* if (chain_length == 0) */
|
|
/* printf("Out of chain length\n"); */
|
|
|
|
return best_len;
|
|
}
|
|
#endif /* ASMV */
|
|
|
|
/* --- check_match() ------------------------------------------------------ */
|
|
|
|
#ifdef DEBUG
|
|
/*
|
|
* Check that the match at match_start is indeed a match.
|
|
*/
|
|
static void check_match(IPos start, IPos match, int length)
|
|
{
|
|
/* check that the match is indeed a match */
|
|
|
|
if (_fmemcmp((char FAR *) window + match,
|
|
(char FAR *) window + start, length) != EQUAL)
|
|
{
|
|
error("invalid match");
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/* --- deflate() --------------------------------------------------------- */
|
|
|
|
/*
|
|
* Processes a new input file and return its compressed length.
|
|
*/
|
|
|
|
#ifdef NO_LAZY
|
|
|
|
static ULONG deflate(void)
|
|
{
|
|
IPos hash_head; /* head of the hash chain */
|
|
int flush; /* set if current block must be flushed */
|
|
USHORT match_length = 0; /* length of best match */
|
|
|
|
prev_length = MIN_MATCH - 1;
|
|
|
|
while (lookahead != 0)
|
|
{
|
|
/* Insert the string window[strstart .. strstart+2] in the
|
|
* dictionary, and set hash_head to the head of the hash chain:
|
|
*/
|
|
if (lookahead > REAL_MIN-1)
|
|
{
|
|
INSERT_STRING(strstart, hash_head);
|
|
}
|
|
else
|
|
{ /* make it do a literal, not adding to hash trees */
|
|
hash_head = NIL;
|
|
match_length = 0;
|
|
}
|
|
|
|
/* Find the longest match, discarding those <= prev_length.
|
|
* At this point we have always match_length < MIN_MATCH
|
|
*/
|
|
|
|
if ((hash_head != NIL) && (strstart - hash_head <= MAX_DIST) &&
|
|
(strstart < 65533))
|
|
{
|
|
/* To simplify the code, we prevent matches with the string
|
|
* of window index 0 (in particular we have to avoid a match
|
|
* of the string with itself at the start of the input file).
|
|
*/
|
|
|
|
match_length = longest_match (hash_head);
|
|
|
|
/* longest_match() sets match_start */
|
|
|
|
if (match_length > lookahead)
|
|
{
|
|
match_length = lookahead;
|
|
}
|
|
}
|
|
|
|
if (match_length >= MIN_MATCH)
|
|
{
|
|
check_match(strstart, match_start, match_length);
|
|
|
|
flush = ct_tally(strstart-match_start, match_length - MIN_MATCH);
|
|
|
|
lookahead -= match_length;
|
|
match_length--; /* string at strstart already in hash table */
|
|
|
|
do
|
|
{
|
|
strstart++;
|
|
|
|
if (lookahead > REAL_MIN-1)
|
|
{
|
|
INSERT_STRING(strstart, hash_head);
|
|
}
|
|
/* strstart never exceeds WSIZE-MAX_MATCH, so there are
|
|
* always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
|
|
* these bytes are garbage, but it does not matter since the
|
|
* next lookahead bytes will always be emitted as literals.
|
|
*/
|
|
} while (--match_length != 0);
|
|
}
|
|
else
|
|
{
|
|
/* No match, output a literal byte */
|
|
|
|
flush = ct_tally (0, window[strstart]);
|
|
lookahead--;
|
|
}
|
|
|
|
strstart++;
|
|
|
|
if (flush)
|
|
{
|
|
FLUSH_BLOCK(0);
|
|
block_start = strstart;
|
|
}
|
|
}
|
|
|
|
return FLUSH_BLOCK(1); /* eof */
|
|
}
|
|
|
|
#else /* LAZY */
|
|
|
|
/*
|
|
* Same as above, but achieves better compression. We use a lazy
|
|
* evaluation for matches: a match is finally adopted only if there is
|
|
* no better match at the next window position.
|
|
*/
|
|
static ULONG deflate(void)
|
|
{
|
|
IPos hash_head; /* head of hash chain */
|
|
IPos prev_match; /* previous match */
|
|
int flush; /* set if current block must be flushed */
|
|
int match_available = 0; /* set if previous match exists */
|
|
register int match_length; /* length of best match */
|
|
|
|
match_length = MIN_MATCH - 1;
|
|
|
|
/* Process the input block */
|
|
|
|
while (lookahead != 0)
|
|
{
|
|
/* Insert the string window[strstart .. strstart+2] in the
|
|
* dictionary, and set hash_head to the head of the hash chain:
|
|
*/
|
|
if (lookahead > (REAL_MIN - 1))
|
|
{
|
|
INSERT_STRING(strstart, hash_head);
|
|
}
|
|
else /* make it do a literal, not adding to hash trees */
|
|
{
|
|
hash_head = NIL;
|
|
prev_length = 0;
|
|
}
|
|
|
|
/* Find the longest match, discarding those <= prev_length */
|
|
|
|
prev_length = match_length;
|
|
prev_match = match_start;
|
|
match_length = MIN_MATCH - 1;
|
|
|
|
if ((hash_head != NIL) && (prev_length < max_lazy_match) &&
|
|
(strstart - hash_head <= MAX_DIST) && (strstart < 65533))
|
|
{
|
|
/* To simplify the code, we prevent matches with the string
|
|
* of window index 0 (in particular we have to avoid a match
|
|
* of the string with itself at the start of the input file).
|
|
*/
|
|
|
|
match_length = longest_match (hash_head);
|
|
/* longest_match() sets match_start */
|
|
|
|
if (match_length > lookahead)
|
|
{
|
|
match_length = lookahead;
|
|
}
|
|
|
|
/* Ignore a length 3 match if it is too distant: */
|
|
if ((match_length == MIN_MATCH) &&
|
|
((strstart - match_start) > TOO_FAR))
|
|
{
|
|
/* If prev_match is also MIN_MATCH, match_start is garbage
|
|
* but we will ignore the current match anyway.
|
|
*/
|
|
match_length--;
|
|
}
|
|
}
|
|
|
|
/* If there was a match at the previous step and the current
|
|
* match is not better, output the previous match: */
|
|
|
|
if ((prev_length >= MIN_MATCH) && (match_length <= prev_length))
|
|
{
|
|
check_match(strstart-1, prev_match, prev_length);
|
|
|
|
flush = ct_tally(strstart-1-prev_match, prev_length - MIN_MATCH);
|
|
|
|
/* Insert in hash table all strings up to the end of the match.
|
|
* strstart-1 and strstart are already inserted.
|
|
*/
|
|
|
|
lookahead -= prev_length-1;
|
|
prev_length -= 2;
|
|
|
|
do
|
|
{
|
|
strstart++;
|
|
|
|
if (lookahead > REAL_MIN-1)
|
|
{
|
|
INSERT_STRING(strstart, hash_head);
|
|
}
|
|
|
|
/* strstart never exceeds WSIZE-MAX_MATCH, so there are
|
|
* always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
|
|
* these bytes are garbage, but it does not matter since the
|
|
* next lookahead bytes will always be emitted as literals.
|
|
*/
|
|
} while (--prev_length != 0);
|
|
|
|
match_available = 0;
|
|
match_length = MIN_MATCH-1;
|
|
strstart++;
|
|
if (flush)
|
|
{
|
|
FLUSH_BLOCK(0);
|
|
block_start = strstart;
|
|
}
|
|
}
|
|
else if (match_available)
|
|
{
|
|
/* If there was no match at the previous position, output a
|
|
* single literal. If there was a match but the current match
|
|
* is longer, truncate the previous match to a single literal.
|
|
*/
|
|
Tracevv((stderr,"%c",window[(USHORT) (strstart-1)]));
|
|
|
|
if (ct_tally (0, window[(USHORT) (strstart-1)]))
|
|
{
|
|
FLUSH_BLOCK(0);
|
|
block_start = strstart;
|
|
}
|
|
|
|
strstart++;
|
|
lookahead--;
|
|
}
|
|
else
|
|
{
|
|
/* There is no previous match to compare with, wait for
|
|
* the next step to decide.
|
|
*/
|
|
match_available = 1;
|
|
strstart++;
|
|
lookahead--;
|
|
}
|
|
}
|
|
|
|
if (match_available)
|
|
{
|
|
ct_tally(0, window[(USHORT) (strstart-1)]);
|
|
}
|
|
|
|
return FLUSH_BLOCK(1); /* eof */
|
|
}
|
|
#endif /* LAZY */
|
|
|
|
/* ------------------------------------------------------------------------ */
|