src/liblzma/lz/lz_encoder_hash.h

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       lz_encoder_hash.h
   4 /// \brief      Hash macros for match finders
   5 //
   6 //  Author:     Igor Pavlov
   7 //
   8 //  This file has been put into the public domain.
   9 //  You can do whatever you want with this file.
  10 //
  11 ///////////////////////////////////////////////////////////////////////////////
  12
  13 #ifndef LZMA_LZ_ENCODER_HASH_H
  14 #define LZMA_LZ_ENCODER_HASH_H
  15
  16 #if defined(WORDS_BIGENDIAN) && !defined(HAVE_SMALL)
  17         // This is to make liblzma produce the same output on big endian
  18         // systems that it does on little endian systems. lz_encoder.c
  19         // takes care of including the actual table.
  20         extern const uint32_t lzma_lz_hash_table[256];
  21 #       define hash_table lzma_lz_hash_table
  22 #else
  23 #       include "check.h"
  24 #       define hash_table lzma_crc32_table[0]
  25 #endif
  26
  27 #define HASH_2_SIZE (UINT32_C(1) << 10)
  28 #define HASH_3_SIZE (UINT32_C(1) << 16)
  29 #define HASH_4_SIZE (UINT32_C(1) << 20)
  30
  31 #define HASH_2_MASK (HASH_2_SIZE - 1)
  32 #define HASH_3_MASK (HASH_3_SIZE - 1)
  33 #define HASH_4_MASK (HASH_4_SIZE - 1)
  34
  35 #define FIX_3_HASH_SIZE (HASH_2_SIZE)
  36 #define FIX_4_HASH_SIZE (HASH_2_SIZE + HASH_3_SIZE)
  37 #define FIX_5_HASH_SIZE (HASH_2_SIZE + HASH_3_SIZE + HASH_4_SIZE)
  38
  39 // Endianness doesn't matter in hash_2_calc() (no effect on the output).
  40 #ifdef TUKLIB_FAST_UNALIGNED_ACCESS
  41 #       define hash_2_calc() \
  42                 const uint32_t hash_value = read16ne(cur)
  43 #else
  44 #       define hash_2_calc() \
  45                 const uint32_t hash_value \
  46                         = (uint32_t)(cur[0]) | ((uint32_t)(cur[1]) << 8)
  47 #endif
  48
  49 #define hash_3_calc() \
  50         const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
  51         const uint32_t hash_2_value = temp & HASH_2_MASK; \
  52         const uint32_t hash_value \
  53                         = (temp ^ ((uint32_t)(cur[2]) << 8)) & mf->hash_mask
  54
  55 #define hash_4_calc() \
  56         const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
  57         const uint32_t hash_2_value = temp & HASH_2_MASK; \
  58         const uint32_t hash_3_value \
  59                         = (temp ^ ((uint32_t)(cur[2]) << 8)) & HASH_3_MASK; \
  60         const uint32_t hash_value = (temp ^ ((uint32_t)(cur[2]) << 8) \
  61                         ^ (hash_table[cur[3]] << 5)) & mf->hash_mask
  62
  63
  64 // The following are not currently used.
  65
  66 #define hash_5_calc() \
  67         const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
  68         const uint32_t hash_2_value = temp & HASH_2_MASK; \
  69         const uint32_t hash_3_value \
  70                         = (temp ^ ((uint32_t)(cur[2]) << 8)) & HASH_3_MASK; \
  71         uint32_t hash_4_value = (temp ^ ((uint32_t)(cur[2]) << 8) ^ \
  72                         ^ hash_table[cur[3]] << 5); \
  73         const uint32_t hash_value \
  74                         = (hash_4_value ^ (hash_table[cur[4]] << 3)) \
  75                                 & mf->hash_mask; \
  76         hash_4_value &= HASH_4_MASK
  77
  78 /*
  79 #define hash_zip_calc() \
  80         const uint32_t hash_value \
  81                         = (((uint32_t)(cur[0]) | ((uint32_t)(cur[1]) << 8)) \
  82                                 ^ hash_table[cur[2]]) & 0xFFFF
  83 */
  84
  85 #define hash_zip_calc() \
  86         const uint32_t hash_value \
  87                         = (((uint32_t)(cur[2]) | ((uint32_t)(cur[0]) << 8)) \
  88                                 ^ hash_table[cur[1]]) & 0xFFFF
  89
  90 #define mt_hash_2_calc() \
  91         const uint32_t hash_2_value \
  92                         = (hash_table[cur[0]] ^ cur[1]) & HASH_2_MASK
  93
  94 #define mt_hash_3_calc() \
  95         const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
  96         const uint32_t hash_2_value = temp & HASH_2_MASK; \
  97         const uint32_t hash_3_value \
  98                         = (temp ^ ((uint32_t)(cur[2]) << 8)) & HASH_3_MASK
  99
 100 #define mt_hash_4_calc() \
 101         const uint32_t temp = hash_table[cur[0]] ^ cur[1]; \
 102         const uint32_t hash_2_value = temp & HASH_2_MASK; \
 103         const uint32_t hash_3_value \
 104                         = (temp ^ ((uint32_t)(cur[2]) << 8)) & HASH_3_MASK; \
 105         const uint32_t hash_4_value = (temp ^ ((uint32_t)(cur[2]) << 8) ^ \
 106                         (hash_table[cur[3]] << 5)) & HASH_4_MASK
 107
 108 #endif