50 lines
1.4 KiB
C
50 lines
1.4 KiB
C
/*
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* fastenc.h
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*
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* Defines for the fast encoder
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*/
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// Size of hash table for std encoder
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#define FAST_ENCODER_HASH_TABLE_SIZE 2048
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#define FAST_ENCODER_HASH_MASK (FAST_ENCODER_HASH_TABLE_SIZE-1)
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#define FAST_ENCODER_HASH_SHIFT 4
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#define FAST_ENCODER_RECALCULATE_HASH(loc) \
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(((window[loc] << (2*FAST_ENCODER_HASH_SHIFT)) ^ \
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(window[loc+1] << FAST_ENCODER_HASH_SHIFT) ^ \
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(window[loc+2])) & FAST_ENCODER_HASH_MASK)
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// Be very careful about increasing the window size; the code tables will have to
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// be updated, since they assume that extra_distance_bits is never larger than a
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// certain size.
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#define FAST_ENCODER_WINDOW_SIZE 8192
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#define FAST_ENCODER_WINDOW_MASK (FAST_ENCODER_WINDOW_SIZE - 1)
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// Don't take a match 3 further away than this
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#define FAST_ENCODER_MATCH3_DIST_THRESHOLD 16384
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typedef struct fast_encoder
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{
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// history window
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BYTE window[2*FAST_ENCODER_WINDOW_SIZE + MAX_MATCH + 4];
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// next most recent occurance of chars with same hash value
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t_search_node prev[FAST_ENCODER_WINDOW_SIZE + MAX_MATCH];
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// hash table to find most recent occurance of chars with same hash value
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t_search_node lookup[FAST_ENCODER_HASH_TABLE_SIZE];
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// have we output our block header (the whole data file will be one big dynamic block)?
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BOOL fOutputBlockHeader;
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} t_fast_encoder;
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