lz_encoder_hash.h

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//
//
//  Author:     Igor Pavlov
//
//  This file has been put into the public domain.
//  You can do whatever you want with this file.
//
 
#ifndef LZMA_LZ_ENCODER_HASH_H
#define LZMA_LZ_ENCODER_HASH_H
 
#if defined(WORDS_BIGENDIAN) && !defined(HAVE_SMALL)
    // This is to make liblzma produce the same output on big endian
    // systems that it does on little endian systems. lz_encoder.c
    // takes care of including the actual table.
    extern const uint32_t lzma_lz_hash_table[256];
#   define hash_table lzma_lz_hash_table
#else
#   include "check.h"
#   define hash_table lzma_crc32_table[0]
#endif
 
#define HASH_2_SIZE (UINT32_C(1) << 10)
#define HASH_3_SIZE (UINT32_C(1) << 16)
#define HASH_4_SIZE (UINT32_C(1) << 20)
 
#define HASH_2_MASK (HASH_2_SIZE - 1)
#define HASH_3_MASK (HASH_3_SIZE - 1)
#define HASH_4_MASK (HASH_4_SIZE - 1)
 
#define FIX_3_HASH_SIZE (HASH_2_SIZE)
#define FIX_4_HASH_SIZE (HASH_2_SIZE + HASH_3_SIZE)
#define FIX_5_HASH_SIZE (HASH_2_SIZE + HASH_3_SIZE + HASH_4_SIZE)
 
// Endianness doesn't matter in hash_2_calc() (no effect on the output).
#ifdef TUKLIB_FAST_UNALIGNED_ACCESS
#   define hash_2_calc() \
        const uint32_t hash_value = read16ne(cur)
#else
#   define hash_2_calc() \
        const uint32_t hash_value \
            = (uint32_t)(cur[0]) | ((uint32_t)(cur[1]) << 8)
#endif
 
#define hash_3_calc() \
    const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
    const uint32_t hash_2_value = temp & HASH_2_MASK; \
    const uint32_t hash_value \
            = (temp ^ ((uint32_t)(cur[2]) << 8)) & mf->hash_mask
 
#define hash_4_calc() \
    const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
    const uint32_t hash_2_value = temp & HASH_2_MASK; \
    const uint32_t hash_3_value \
            = (temp ^ ((uint32_t)(cur[2]) << 8)) & HASH_3_MASK; \
    const uint32_t hash_value = (temp ^ ((uint32_t)(cur[2]) << 8) \
            ^ (hash_table[cur[3]] << 5)) & mf->hash_mask
 
 
// The following are not currently used.
 
#define hash_5_calc() \
    const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
    const uint32_t hash_2_value = temp & HASH_2_MASK; \
    const uint32_t hash_3_value \
            = (temp ^ ((uint32_t)(cur[2]) << 8)) & HASH_3_MASK; \
    uint32_t hash_4_value = (temp ^ ((uint32_t)(cur[2]) << 8) ^ \
            ^ hash_table[cur[3]] << 5); \
    const uint32_t hash_value \
            = (hash_4_value ^ (hash_table[cur[4]] << 3)) \
                & mf->hash_mask; \
    hash_4_value &= HASH_4_MASK
 
/*
#define hash_zip_calc() \
    const uint32_t hash_value \
            = (((uint32_t)(cur[0]) | ((uint32_t)(cur[1]) << 8)) \
                ^ hash_table[cur[2]]) & 0xFFFF
*/
 
#define hash_zip_calc() \
    const uint32_t hash_value \
            = (((uint32_t)(cur[2]) | ((uint32_t)(cur[0]) << 8)) \
                ^ hash_table[cur[1]]) & 0xFFFF
 
#define mt_hash_2_calc() \
    const uint32_t hash_2_value \
            = (hash_table[cur[0]] ^ cur[1]) & HASH_2_MASK
 
#define mt_hash_3_calc() \
    const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
    const uint32_t hash_2_value = temp & HASH_2_MASK; \
    const uint32_t hash_3_value \
            = (temp ^ ((uint32_t)(cur[2]) << 8)) & HASH_3_MASK
 
#define mt_hash_4_calc() \
    const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
    const uint32_t hash_2_value = temp & HASH_2_MASK; \
    const uint32_t hash_3_value \
            = (temp ^ ((uint32_t)(cur[2]) << 8)) & HASH_3_MASK; \
    const uint32_t hash_4_value = (temp ^ ((uint32_t)(cur[2]) << 8) ^ \
            (hash_table[cur[3]] << 5)) & HASH_4_MASK
 
#endif