79 lines
1.6 KiB
C
79 lines
1.6 KiB
C
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// infinput.c
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// Bitwise inputting for inflate (decompressor)
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#include <stdio.h>
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#include <crtdbg.h>
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#include "inflate.h"
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#include "infmacro.h"
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void dumpBits(t_decoder_context *context, int n)
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{
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context->bitbuf >>= n;
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context->bitcount -= n;
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}
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// retrieve n bits from the bit buffer, and dump them when done
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// n can be up to 16
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int getBits(t_decoder_context *context, int n)
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{
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int result;
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context->bitcount -= n;
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result = (context->bitbuf & g_BitMask[n]);
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context->bitbuf >>= n;
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return result;
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}
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// Ensure that <num_bits> bits are in the bit buffer
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// Returns FALSE if there are not and there was insufficient input to make this true
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BOOL ensureBitsContext(t_decoder_context *context, int num_bits)
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{
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if (context->bitcount + 16 < num_bits)
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{
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if (INPUT_EOF())
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return FALSE;
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context->bitbuf |= ((*context->input_curpos++) << (context->bitcount+16));
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context->bitcount += 8;
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if (context->bitcount + 16 < num_bits)
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{
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if (INPUT_EOF())
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return FALSE;
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context->bitbuf |= ((*context->input_curpos++) << (context->bitcount+16));
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context->bitcount += 8;
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}
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}
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return TRUE;
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}
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// initialise the bit buffer
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BOOL initBitBuffer(t_decoder_context *context)
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{
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if (context->input_curpos < context->end_input_buffer)
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{
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context->bitbuf = *context->input_curpos++;
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context->bitcount = -8;
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context->state = STATE_READING_BFINAL;
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return TRUE;
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}
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else
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{
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context->bitcount = -16;
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context->bitbuf = 0;
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return FALSE;
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}
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}
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