1 | /* lzo1x_9x.c -- implementation of the LZO1X-999 compression algorithm
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2 |
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3 | This file is part of the LZO real-time data compression library.
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4 |
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5 | Copyright (C) 2008 Markus Franz Xaver Johannes Oberhumer
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6 | Copyright (C) 2007 Markus Franz Xaver Johannes Oberhumer
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7 | Copyright (C) 2006 Markus Franz Xaver Johannes Oberhumer
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8 | Copyright (C) 2005 Markus Franz Xaver Johannes Oberhumer
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9 | Copyright (C) 2004 Markus Franz Xaver Johannes Oberhumer
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10 | Copyright (C) 2003 Markus Franz Xaver Johannes Oberhumer
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11 | Copyright (C) 2002 Markus Franz Xaver Johannes Oberhumer
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12 | Copyright (C) 2001 Markus Franz Xaver Johannes Oberhumer
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13 | Copyright (C) 2000 Markus Franz Xaver Johannes Oberhumer
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14 | Copyright (C) 1999 Markus Franz Xaver Johannes Oberhumer
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15 | Copyright (C) 1998 Markus Franz Xaver Johannes Oberhumer
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16 | Copyright (C) 1997 Markus Franz Xaver Johannes Oberhumer
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17 | Copyright (C) 1996 Markus Franz Xaver Johannes Oberhumer
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18 | All Rights Reserved.
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19 |
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20 | The LZO library is free software; you can redistribute it and/or
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21 | modify it under the terms of the GNU General Public License as
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22 | published by the Free Software Foundation; either version 2 of
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23 | the License, or (at your option) any later version.
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24 |
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25 | The LZO library is distributed in the hope that it will be useful,
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26 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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27 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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28 | GNU General Public License for more details.
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29 |
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30 | You should have received a copy of the GNU General Public License
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31 | along with the LZO library; see the file COPYING.
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32 | If not, write to the Free Software Foundation, Inc.,
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33 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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34 |
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35 | Markus F.X.J. Oberhumer
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36 | <markus@oberhumer.com>
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37 | http://www.oberhumer.com/opensource/lzo/
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38 | */
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39 | #include "libbb.h"
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40 |
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41 | /* The following is probably only safe on Intel-compatible processors ... */
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42 | #define LZO_UNALIGNED_OK_2
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43 | #define LZO_UNALIGNED_OK_4
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44 |
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45 | #include "liblzo.h"
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46 |
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47 | #define LZO_MAX(a,b) ((a) >= (b) ? (a) : (b))
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48 | #define LZO_MIN(a,b) ((a) <= (b) ? (a) : (b))
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49 | #define LZO_MAX3(a,b,c) ((a) >= (b) ? LZO_MAX(a,c) : LZO_MAX(b,c))
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50 |
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51 | /***********************************************************************
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52 | //
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53 | ************************************************************************/
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54 | #define SWD_N M4_MAX_OFFSET /* size of ring buffer */
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55 | #define SWD_F 2048 /* upper limit for match length */
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56 |
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57 | #define SWD_BEST_OFF (LZO_MAX3(M2_MAX_LEN, M3_MAX_LEN, M4_MAX_LEN) + 1)
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58 |
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59 | typedef struct {
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60 | int init;
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61 |
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62 | unsigned look; /* bytes in lookahead buffer */
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63 |
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64 | unsigned m_len;
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65 | unsigned m_off;
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66 |
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67 | const uint8_t *bp;
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68 | const uint8_t *ip;
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69 | const uint8_t *in;
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70 | const uint8_t *in_end;
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71 | uint8_t *out;
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72 |
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73 | unsigned r1_lit;
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74 | } lzo1x_999_t;
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75 |
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76 | #define getbyte(c) ((c).ip < (c).in_end ? *((c).ip)++ : (-1))
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77 |
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78 | /* lzo_swd.c -- sliding window dictionary */
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79 |
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80 | /***********************************************************************
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81 | //
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82 | ************************************************************************/
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83 | #define SWD_UINT_MAX USHRT_MAX
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84 |
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85 | #ifndef SWD_HSIZE
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86 | # define SWD_HSIZE 16384
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87 | #endif
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88 | #ifndef SWD_MAX_CHAIN
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89 | # define SWD_MAX_CHAIN 2048
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90 | #endif
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91 |
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92 | #define HEAD3(b, p) \
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93 | ( ((0x9f5f * ((((b[p]<<5)^b[p+1])<<5) ^ b[p+2])) >> 5) & (SWD_HSIZE-1) )
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94 |
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95 | #if defined(LZO_UNALIGNED_OK_2)
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96 | # define HEAD2(b,p) (* (bb__aliased_uint16_t *) &(b[p]))
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97 | #else
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98 | # define HEAD2(b,p) (b[p] ^ ((unsigned)b[p+1]<<8))
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99 | #endif
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100 | #define NIL2 SWD_UINT_MAX
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101 |
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102 | typedef struct lzo_swd {
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103 | /* public - "built-in" */
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104 |
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105 | /* public - configuration */
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106 | unsigned max_chain;
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107 | int use_best_off;
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108 |
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109 | /* public - output */
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110 | unsigned m_len;
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111 | unsigned m_off;
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112 | unsigned look;
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113 | int b_char;
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114 | #if defined(SWD_BEST_OFF)
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115 | unsigned best_off[SWD_BEST_OFF];
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116 | #endif
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117 |
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118 | /* semi public */
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119 | lzo1x_999_t *c;
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120 | unsigned m_pos;
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121 | #if defined(SWD_BEST_OFF)
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122 | unsigned best_pos[SWD_BEST_OFF];
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123 | #endif
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124 |
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125 | /* private */
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126 | unsigned ip; /* input pointer (lookahead) */
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127 | unsigned bp; /* buffer pointer */
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128 | unsigned rp; /* remove pointer */
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129 |
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130 | unsigned node_count;
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131 | unsigned first_rp;
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132 |
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133 | uint8_t b[SWD_N + SWD_F];
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134 | uint8_t b_wrap[SWD_F]; /* must follow b */
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135 | uint16_t head3[SWD_HSIZE];
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136 | uint16_t succ3[SWD_N + SWD_F];
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137 | uint16_t best3[SWD_N + SWD_F];
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138 | uint16_t llen3[SWD_HSIZE];
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139 | #ifdef HEAD2
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140 | uint16_t head2[65536L];
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141 | #endif
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142 | } lzo_swd_t, *lzo_swd_p;
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143 |
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144 | #define SIZEOF_LZO_SWD_T (sizeof(lzo_swd_t))
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145 |
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146 |
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147 | /* Access macro for head3.
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148 | * head3[key] may be uninitialized, but then its value will never be used.
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149 | */
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150 | #define s_get_head3(s,key) s->head3[key]
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151 |
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152 |
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153 | /***********************************************************************
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154 | //
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155 | ************************************************************************/
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156 | #define B_SIZE (SWD_N + SWD_F)
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157 |
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158 | static int swd_init(lzo_swd_p s)
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159 | {
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160 | /* defaults */
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161 | s->node_count = SWD_N;
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162 |
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163 | memset(s->llen3, 0, sizeof(s->llen3[0]) * (unsigned)SWD_HSIZE);
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164 | #ifdef HEAD2
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165 | memset(s->head2, 0xff, sizeof(s->head2[0]) * 65536L);
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166 | assert(s->head2[0] == NIL2);
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167 | #endif
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168 |
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169 | s->ip = 0;
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170 | s->bp = s->ip;
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171 | s->first_rp = s->ip;
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172 |
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173 | assert(s->ip + SWD_F <= B_SIZE);
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174 | s->look = (unsigned) (s->c->in_end - s->c->ip);
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175 | if (s->look > 0) {
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176 | if (s->look > SWD_F)
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177 | s->look = SWD_F;
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178 | memcpy(&s->b[s->ip], s->c->ip, s->look);
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179 | s->c->ip += s->look;
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180 | s->ip += s->look;
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181 | }
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182 | if (s->ip == B_SIZE)
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183 | s->ip = 0;
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184 |
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185 | s->rp = s->first_rp;
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186 | if (s->rp >= s->node_count)
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187 | s->rp -= s->node_count;
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188 | else
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189 | s->rp += B_SIZE - s->node_count;
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190 |
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191 | return LZO_E_OK;
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192 | }
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193 |
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194 | #define swd_pos2off(s,pos) \
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195 | (s->bp > (pos) ? s->bp - (pos) : B_SIZE - ((pos) - s->bp))
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196 |
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197 |
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198 | /***********************************************************************
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199 | //
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200 | ************************************************************************/
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201 | static void swd_getbyte(lzo_swd_p s)
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202 | {
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203 | int c;
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204 |
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205 | if ((c = getbyte(*(s->c))) < 0) {
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206 | if (s->look > 0)
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207 | --s->look;
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208 | } else {
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209 | s->b[s->ip] = c;
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210 | if (s->ip < SWD_F)
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211 | s->b_wrap[s->ip] = c;
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212 | }
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213 | if (++s->ip == B_SIZE)
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214 | s->ip = 0;
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215 | if (++s->bp == B_SIZE)
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216 | s->bp = 0;
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217 | if (++s->rp == B_SIZE)
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218 | s->rp = 0;
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219 | }
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220 |
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221 |
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222 | /***********************************************************************
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223 | // remove node from lists
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224 | ************************************************************************/
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225 | static void swd_remove_node(lzo_swd_p s, unsigned node)
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226 | {
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227 | if (s->node_count == 0) {
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228 | unsigned key;
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229 |
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230 | key = HEAD3(s->b,node);
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231 | assert(s->llen3[key] > 0);
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232 | --s->llen3[key];
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233 |
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234 | #ifdef HEAD2
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235 | key = HEAD2(s->b,node);
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236 | assert(s->head2[key] != NIL2);
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237 | if ((unsigned) s->head2[key] == node)
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238 | s->head2[key] = NIL2;
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239 | #endif
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240 | } else
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241 | --s->node_count;
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242 | }
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243 |
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244 |
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245 | /***********************************************************************
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246 | //
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247 | ************************************************************************/
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248 | static void swd_accept(lzo_swd_p s, unsigned n)
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249 | {
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250 | assert(n <= s->look);
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251 |
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252 | while (n--) {
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253 | unsigned key;
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254 |
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255 | swd_remove_node(s,s->rp);
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256 |
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257 | /* add bp into HEAD3 */
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258 | key = HEAD3(s->b, s->bp);
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259 | s->succ3[s->bp] = s_get_head3(s, key);
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260 | s->head3[key] = s->bp;
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261 | s->best3[s->bp] = SWD_F + 1;
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262 | s->llen3[key]++;
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263 | assert(s->llen3[key] <= SWD_N);
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264 |
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265 | #ifdef HEAD2
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266 | /* add bp into HEAD2 */
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267 | key = HEAD2(s->b, s->bp);
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268 | s->head2[key] = s->bp;
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269 | #endif
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270 |
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271 | swd_getbyte(s);
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272 | }
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273 | }
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274 |
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275 |
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276 | /***********************************************************************
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277 | //
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278 | ************************************************************************/
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279 | static void swd_search(lzo_swd_p s, unsigned node, unsigned cnt)
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280 | {
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281 | const uint8_t *p1;
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282 | const uint8_t *p2;
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283 | const uint8_t *px;
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284 | unsigned m_len = s->m_len;
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285 | const uint8_t *b = s->b;
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286 | const uint8_t *bp = s->b + s->bp;
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287 | const uint8_t *bx = s->b + s->bp + s->look;
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288 | unsigned char scan_end1;
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289 |
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290 | assert(s->m_len > 0);
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291 |
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292 | scan_end1 = bp[m_len - 1];
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293 | for ( ; cnt-- > 0; node = s->succ3[node]) {
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294 | p1 = bp;
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295 | p2 = b + node;
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296 | px = bx;
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297 |
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298 | assert(m_len < s->look);
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299 |
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300 | if (p2[m_len - 1] == scan_end1
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301 | && p2[m_len] == p1[m_len]
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302 | && p2[0] == p1[0]
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303 | && p2[1] == p1[1]
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304 | ) {
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305 | unsigned i;
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306 | assert(lzo_memcmp(bp, &b[node], 3) == 0);
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307 |
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308 | p1 += 2; p2 += 2;
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309 | do {} while (++p1 < px && *p1 == *++p2);
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310 | i = p1-bp;
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311 |
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312 | assert(lzo_memcmp(bp, &b[node], i) == 0);
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313 |
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314 | #if defined(SWD_BEST_OFF)
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315 | if (i < SWD_BEST_OFF) {
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316 | if (s->best_pos[i] == 0)
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317 | s->best_pos[i] = node + 1;
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318 | }
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319 | #endif
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320 | if (i > m_len) {
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321 | s->m_len = m_len = i;
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322 | s->m_pos = node;
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323 | if (m_len == s->look)
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324 | return;
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325 | if (m_len >= SWD_F)
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326 | return;
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327 | if (m_len > (unsigned) s->best3[node])
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328 | return;
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329 | scan_end1 = bp[m_len - 1];
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330 | }
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331 | }
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332 | }
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333 | }
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334 |
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335 |
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336 | /***********************************************************************
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337 | //
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338 | ************************************************************************/
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339 | #ifdef HEAD2
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340 |
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341 | static int swd_search2(lzo_swd_p s)
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342 | {
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343 | unsigned key;
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344 |
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345 | assert(s->look >= 2);
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346 | assert(s->m_len > 0);
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347 |
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348 | key = s->head2[HEAD2(s->b, s->bp)];
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349 | if (key == NIL2)
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350 | return 0;
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351 | assert(lzo_memcmp(&s->b[s->bp], &s->b[key], 2) == 0);
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352 | #if defined(SWD_BEST_OFF)
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353 | if (s->best_pos[2] == 0)
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354 | s->best_pos[2] = key + 1;
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355 | #endif
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356 |
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357 | if (s->m_len < 2) {
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358 | s->m_len = 2;
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359 | s->m_pos = key;
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360 | }
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361 | return 1;
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362 | }
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363 |
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364 | #endif
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365 |
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366 |
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367 | /***********************************************************************
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368 | //
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369 | ************************************************************************/
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370 | static void swd_findbest(lzo_swd_p s)
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371 | {
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372 | unsigned key;
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373 | unsigned cnt, node;
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374 | unsigned len;
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375 |
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376 | assert(s->m_len > 0);
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377 |
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378 | /* get current head, add bp into HEAD3 */
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379 | key = HEAD3(s->b,s->bp);
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380 | node = s->succ3[s->bp] = s_get_head3(s, key);
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381 | cnt = s->llen3[key]++;
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382 | assert(s->llen3[key] <= SWD_N + SWD_F);
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383 | if (cnt > s->max_chain)
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384 | cnt = s->max_chain;
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385 | s->head3[key] = s->bp;
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386 |
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387 | s->b_char = s->b[s->bp];
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388 | len = s->m_len;
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389 | if (s->m_len >= s->look) {
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390 | if (s->look == 0)
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391 | s->b_char = -1;
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392 | s->m_off = 0;
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393 | s->best3[s->bp] = SWD_F + 1;
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394 | } else {
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395 | #ifdef HEAD2
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396 | if (swd_search2(s))
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397 | #endif
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398 | if (s->look >= 3)
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399 | swd_search(s, node, cnt);
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400 | if (s->m_len > len)
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401 | s->m_off = swd_pos2off(s,s->m_pos);
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402 | s->best3[s->bp] = s->m_len;
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403 |
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404 | #if defined(SWD_BEST_OFF)
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405 | if (s->use_best_off) {
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406 | int i;
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407 | for (i = 2; i < SWD_BEST_OFF; i++) {
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408 | if (s->best_pos[i] > 0)
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409 | s->best_off[i] = swd_pos2off(s, s->best_pos[i]-1);
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410 | else
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411 | s->best_off[i] = 0;
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412 | }
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413 | }
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414 | #endif
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415 | }
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416 |
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417 | swd_remove_node(s,s->rp);
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418 |
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419 | #ifdef HEAD2
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420 | /* add bp into HEAD2 */
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421 | key = HEAD2(s->b, s->bp);
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422 | s->head2[key] = s->bp;
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423 | #endif
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424 | }
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425 |
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426 | #undef HEAD3
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427 | #undef HEAD2
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428 | #undef s_get_head3
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429 |
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430 |
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431 | /***********************************************************************
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432 | //
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433 | ************************************************************************/
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434 | static int init_match(lzo1x_999_t *c, lzo_swd_p s, uint32_t use_best_off)
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435 | {
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436 | int r;
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437 |
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438 | assert(!c->init);
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439 | c->init = 1;
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440 |
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441 | s->c = c;
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442 |
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443 | r = swd_init(s);
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444 | if (r != 0)
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445 | return r;
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446 |
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447 | s->use_best_off = use_best_off;
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448 | return r;
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449 | }
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450 |
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451 |
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452 | /***********************************************************************
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453 | //
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454 | ************************************************************************/
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455 | static int find_match(lzo1x_999_t *c, lzo_swd_p s,
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456 | unsigned this_len, unsigned skip)
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457 | {
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458 | assert(c->init);
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459 |
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460 | if (skip > 0) {
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461 | assert(this_len >= skip);
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462 | swd_accept(s, this_len - skip);
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463 | } else {
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---|
464 | assert(this_len <= 1);
|
---|
465 | }
|
---|
466 |
|
---|
467 | s->m_len = 1;
|
---|
468 | #ifdef SWD_BEST_OFF
|
---|
469 | if (s->use_best_off)
|
---|
470 | memset(s->best_pos, 0, sizeof(s->best_pos));
|
---|
471 | #endif
|
---|
472 | swd_findbest(s);
|
---|
473 | c->m_len = s->m_len;
|
---|
474 | c->m_off = s->m_off;
|
---|
475 |
|
---|
476 | swd_getbyte(s);
|
---|
477 |
|
---|
478 | if (s->b_char < 0) {
|
---|
479 | c->look = 0;
|
---|
480 | c->m_len = 0;
|
---|
481 | } else {
|
---|
482 | c->look = s->look + 1;
|
---|
483 | }
|
---|
484 | c->bp = c->ip - c->look;
|
---|
485 |
|
---|
486 | return LZO_E_OK;
|
---|
487 | }
|
---|
488 |
|
---|
489 | /* this is a public functions, but there is no prototype in a header file */
|
---|
490 | static int lzo1x_999_compress_internal(const uint8_t *in , unsigned in_len,
|
---|
491 | uint8_t *out, unsigned *out_len,
|
---|
492 | void *wrkmem,
|
---|
493 | unsigned good_length,
|
---|
494 | unsigned max_lazy,
|
---|
495 | unsigned max_chain,
|
---|
496 | uint32_t use_best_off);
|
---|
497 |
|
---|
498 |
|
---|
499 | /***********************************************************************
|
---|
500 | //
|
---|
501 | ************************************************************************/
|
---|
502 | static uint8_t *code_match(lzo1x_999_t *c,
|
---|
503 | uint8_t *op, unsigned m_len, unsigned m_off)
|
---|
504 | {
|
---|
505 | assert(op > c->out);
|
---|
506 | if (m_len == 2) {
|
---|
507 | assert(m_off <= M1_MAX_OFFSET);
|
---|
508 | assert(c->r1_lit > 0);
|
---|
509 | assert(c->r1_lit < 4);
|
---|
510 | m_off -= 1;
|
---|
511 | *op++ = M1_MARKER | ((m_off & 3) << 2);
|
---|
512 | *op++ = m_off >> 2;
|
---|
513 | } else if (m_len <= M2_MAX_LEN && m_off <= M2_MAX_OFFSET) {
|
---|
514 | assert(m_len >= 3);
|
---|
515 | m_off -= 1;
|
---|
516 | *op++ = ((m_len - 1) << 5) | ((m_off & 7) << 2);
|
---|
517 | *op++ = m_off >> 3;
|
---|
518 | assert(op[-2] >= M2_MARKER);
|
---|
519 | } else if (m_len == M2_MIN_LEN && m_off <= MX_MAX_OFFSET && c->r1_lit >= 4) {
|
---|
520 | assert(m_len == 3);
|
---|
521 | assert(m_off > M2_MAX_OFFSET);
|
---|
522 | m_off -= 1 + M2_MAX_OFFSET;
|
---|
523 | *op++ = M1_MARKER | ((m_off & 3) << 2);
|
---|
524 | *op++ = m_off >> 2;
|
---|
525 | } else if (m_off <= M3_MAX_OFFSET) {
|
---|
526 | assert(m_len >= 3);
|
---|
527 | m_off -= 1;
|
---|
528 | if (m_len <= M3_MAX_LEN)
|
---|
529 | *op++ = M3_MARKER | (m_len - 2);
|
---|
530 | else {
|
---|
531 | m_len -= M3_MAX_LEN;
|
---|
532 | *op++ = M3_MARKER | 0;
|
---|
533 | while (m_len > 255) {
|
---|
534 | m_len -= 255;
|
---|
535 | *op++ = 0;
|
---|
536 | }
|
---|
537 | assert(m_len > 0);
|
---|
538 | *op++ = m_len;
|
---|
539 | }
|
---|
540 | *op++ = m_off << 2;
|
---|
541 | *op++ = m_off >> 6;
|
---|
542 | } else {
|
---|
543 | unsigned k;
|
---|
544 |
|
---|
545 | assert(m_len >= 3);
|
---|
546 | assert(m_off > 0x4000);
|
---|
547 | assert(m_off <= 0xbfff);
|
---|
548 | m_off -= 0x4000;
|
---|
549 | k = (m_off & 0x4000) >> 11;
|
---|
550 | if (m_len <= M4_MAX_LEN)
|
---|
551 | *op++ = M4_MARKER | k | (m_len - 2);
|
---|
552 | else {
|
---|
553 | m_len -= M4_MAX_LEN;
|
---|
554 | *op++ = M4_MARKER | k | 0;
|
---|
555 | while (m_len > 255) {
|
---|
556 | m_len -= 255;
|
---|
557 | *op++ = 0;
|
---|
558 | }
|
---|
559 | assert(m_len > 0);
|
---|
560 | *op++ = m_len;
|
---|
561 | }
|
---|
562 | *op++ = m_off << 2;
|
---|
563 | *op++ = m_off >> 6;
|
---|
564 | }
|
---|
565 |
|
---|
566 | return op;
|
---|
567 | }
|
---|
568 |
|
---|
569 |
|
---|
570 | static uint8_t *STORE_RUN(lzo1x_999_t *c, uint8_t *op,
|
---|
571 | const uint8_t *ii, unsigned t)
|
---|
572 | {
|
---|
573 | if (op == c->out && t <= 238) {
|
---|
574 | *op++ = 17 + t;
|
---|
575 | } else if (t <= 3) {
|
---|
576 | op[-2] |= t;
|
---|
577 | } else if (t <= 18) {
|
---|
578 | *op++ = t - 3;
|
---|
579 | } else {
|
---|
580 | unsigned tt = t - 18;
|
---|
581 |
|
---|
582 | *op++ = 0;
|
---|
583 | while (tt > 255) {
|
---|
584 | tt -= 255;
|
---|
585 | *op++ = 0;
|
---|
586 | }
|
---|
587 | assert(tt > 0);
|
---|
588 | *op++ = tt;
|
---|
589 | }
|
---|
590 | do *op++ = *ii++; while (--t > 0);
|
---|
591 |
|
---|
592 | return op;
|
---|
593 | }
|
---|
594 |
|
---|
595 |
|
---|
596 | static uint8_t *code_run(lzo1x_999_t *c, uint8_t *op, const uint8_t *ii,
|
---|
597 | unsigned lit)
|
---|
598 | {
|
---|
599 | if (lit > 0) {
|
---|
600 | assert(m_len >= 2);
|
---|
601 | op = STORE_RUN(c, op, ii, lit);
|
---|
602 | } else {
|
---|
603 | assert(m_len >= 3);
|
---|
604 | }
|
---|
605 | c->r1_lit = lit;
|
---|
606 |
|
---|
607 | return op;
|
---|
608 | }
|
---|
609 |
|
---|
610 |
|
---|
611 | /***********************************************************************
|
---|
612 | //
|
---|
613 | ************************************************************************/
|
---|
614 | static int len_of_coded_match(unsigned m_len, unsigned m_off, unsigned lit)
|
---|
615 | {
|
---|
616 | int n = 4;
|
---|
617 |
|
---|
618 | if (m_len < 2)
|
---|
619 | return -1;
|
---|
620 | if (m_len == 2)
|
---|
621 | return (m_off <= M1_MAX_OFFSET && lit > 0 && lit < 4) ? 2 : -1;
|
---|
622 | if (m_len <= M2_MAX_LEN && m_off <= M2_MAX_OFFSET)
|
---|
623 | return 2;
|
---|
624 | if (m_len == M2_MIN_LEN && m_off <= MX_MAX_OFFSET && lit >= 4)
|
---|
625 | return 2;
|
---|
626 | if (m_off <= M3_MAX_OFFSET) {
|
---|
627 | if (m_len <= M3_MAX_LEN)
|
---|
628 | return 3;
|
---|
629 | m_len -= M3_MAX_LEN;
|
---|
630 | } else if (m_off <= M4_MAX_OFFSET) {
|
---|
631 | if (m_len <= M4_MAX_LEN)
|
---|
632 | return 3;
|
---|
633 | m_len -= M4_MAX_LEN;
|
---|
634 | } else
|
---|
635 | return -1;
|
---|
636 | while (m_len > 255) {
|
---|
637 | m_len -= 255;
|
---|
638 | n++;
|
---|
639 | }
|
---|
640 | return n;
|
---|
641 | }
|
---|
642 |
|
---|
643 |
|
---|
644 | static int min_gain(unsigned ahead, unsigned lit1,
|
---|
645 | unsigned lit2, int l1, int l2, int l3)
|
---|
646 | {
|
---|
647 | int lazy_match_min_gain = 0;
|
---|
648 |
|
---|
649 | assert (ahead >= 1);
|
---|
650 | lazy_match_min_gain += ahead;
|
---|
651 |
|
---|
652 | if (lit1 <= 3)
|
---|
653 | lazy_match_min_gain += (lit2 <= 3) ? 0 : 2;
|
---|
654 | else if (lit1 <= 18)
|
---|
655 | lazy_match_min_gain += (lit2 <= 18) ? 0 : 1;
|
---|
656 |
|
---|
657 | lazy_match_min_gain += (l2 - l1) * 2;
|
---|
658 | if (l3 > 0)
|
---|
659 | lazy_match_min_gain -= (ahead - l3) * 2;
|
---|
660 |
|
---|
661 | if (lazy_match_min_gain < 0)
|
---|
662 | lazy_match_min_gain = 0;
|
---|
663 |
|
---|
664 | return lazy_match_min_gain;
|
---|
665 | }
|
---|
666 |
|
---|
667 |
|
---|
668 | /***********************************************************************
|
---|
669 | //
|
---|
670 | ************************************************************************/
|
---|
671 | #if defined(SWD_BEST_OFF)
|
---|
672 |
|
---|
673 | static void better_match(const lzo_swd_p swd,
|
---|
674 | unsigned *m_len, unsigned *m_off)
|
---|
675 | {
|
---|
676 | if (*m_len <= M2_MIN_LEN)
|
---|
677 | return;
|
---|
678 |
|
---|
679 | if (*m_off <= M2_MAX_OFFSET)
|
---|
680 | return;
|
---|
681 |
|
---|
682 | /* M3/M4 -> M2 */
|
---|
683 | if (*m_off > M2_MAX_OFFSET
|
---|
684 | && *m_len >= M2_MIN_LEN + 1 && *m_len <= M2_MAX_LEN + 1
|
---|
685 | && swd->best_off[*m_len-1] && swd->best_off[*m_len-1] <= M2_MAX_OFFSET
|
---|
686 | ) {
|
---|
687 | *m_len = *m_len - 1;
|
---|
688 | *m_off = swd->best_off[*m_len];
|
---|
689 | return;
|
---|
690 | }
|
---|
691 |
|
---|
692 | /* M4 -> M2 */
|
---|
693 | if (*m_off > M3_MAX_OFFSET
|
---|
694 | && *m_len >= M4_MAX_LEN + 1 && *m_len <= M2_MAX_LEN + 2
|
---|
695 | && swd->best_off[*m_len-2] && swd->best_off[*m_len-2] <= M2_MAX_OFFSET
|
---|
696 | ) {
|
---|
697 | *m_len = *m_len - 2;
|
---|
698 | *m_off = swd->best_off[*m_len];
|
---|
699 | return;
|
---|
700 | }
|
---|
701 | /* M4 -> M3 */
|
---|
702 | if (*m_off > M3_MAX_OFFSET
|
---|
703 | && *m_len >= M4_MAX_LEN + 1 && *m_len <= M3_MAX_LEN + 1
|
---|
704 | && swd->best_off[*m_len-1] && swd->best_off[*m_len-1] <= M3_MAX_OFFSET
|
---|
705 | ) {
|
---|
706 | *m_len = *m_len - 1;
|
---|
707 | *m_off = swd->best_off[*m_len];
|
---|
708 | }
|
---|
709 | }
|
---|
710 |
|
---|
711 | #endif
|
---|
712 |
|
---|
713 |
|
---|
714 | /***********************************************************************
|
---|
715 | //
|
---|
716 | ************************************************************************/
|
---|
717 | static int lzo1x_999_compress_internal(const uint8_t *in, unsigned in_len,
|
---|
718 | uint8_t *out, unsigned *out_len,
|
---|
719 | void *wrkmem,
|
---|
720 | unsigned good_length,
|
---|
721 | unsigned max_lazy,
|
---|
722 | unsigned max_chain,
|
---|
723 | uint32_t use_best_off)
|
---|
724 | {
|
---|
725 | uint8_t *op;
|
---|
726 | const uint8_t *ii;
|
---|
727 | unsigned lit;
|
---|
728 | unsigned m_len, m_off;
|
---|
729 | lzo1x_999_t cc;
|
---|
730 | lzo1x_999_t *const c = &cc;
|
---|
731 | const lzo_swd_p swd = (lzo_swd_p) wrkmem;
|
---|
732 | int r;
|
---|
733 |
|
---|
734 | c->init = 0;
|
---|
735 | c->ip = c->in = in;
|
---|
736 | c->in_end = in + in_len;
|
---|
737 | c->out = out;
|
---|
738 |
|
---|
739 | op = out;
|
---|
740 | ii = c->ip; /* point to start of literal run */
|
---|
741 | lit = 0;
|
---|
742 | c->r1_lit = 0;
|
---|
743 |
|
---|
744 | r = init_match(c, swd, use_best_off);
|
---|
745 | if (r != 0)
|
---|
746 | return r;
|
---|
747 | swd->max_chain = max_chain;
|
---|
748 |
|
---|
749 | r = find_match(c, swd, 0, 0);
|
---|
750 | if (r != 0)
|
---|
751 | return r;
|
---|
752 |
|
---|
753 | while (c->look > 0) {
|
---|
754 | unsigned ahead;
|
---|
755 | unsigned max_ahead;
|
---|
756 | int l1, l2, l3;
|
---|
757 |
|
---|
758 | m_len = c->m_len;
|
---|
759 | m_off = c->m_off;
|
---|
760 |
|
---|
761 | assert(c->bp == c->ip - c->look);
|
---|
762 | assert(c->bp >= in);
|
---|
763 | if (lit == 0)
|
---|
764 | ii = c->bp;
|
---|
765 | assert(ii + lit == c->bp);
|
---|
766 | assert(swd->b_char == *(c->bp));
|
---|
767 |
|
---|
768 | if (m_len < 2
|
---|
769 | || (m_len == 2 && (m_off > M1_MAX_OFFSET || lit == 0 || lit >= 4))
|
---|
770 | /* Do not accept this match for compressed-data compatibility
|
---|
771 | * with LZO v1.01 and before
|
---|
772 | * [ might be a problem for decompress() and optimize() ]
|
---|
773 | */
|
---|
774 | || (m_len == 2 && op == out)
|
---|
775 | || (op == out && lit == 0)
|
---|
776 | ) {
|
---|
777 | /* a literal */
|
---|
778 | m_len = 0;
|
---|
779 | }
|
---|
780 | else if (m_len == M2_MIN_LEN) {
|
---|
781 | /* compression ratio improves if we code a literal in some cases */
|
---|
782 | if (m_off > MX_MAX_OFFSET && lit >= 4)
|
---|
783 | m_len = 0;
|
---|
784 | }
|
---|
785 |
|
---|
786 | if (m_len == 0) {
|
---|
787 | /* a literal */
|
---|
788 | lit++;
|
---|
789 | swd->max_chain = max_chain;
|
---|
790 | r = find_match(c, swd, 1, 0);
|
---|
791 | assert(r == 0);
|
---|
792 | continue;
|
---|
793 | }
|
---|
794 |
|
---|
795 | /* a match */
|
---|
796 | #if defined(SWD_BEST_OFF)
|
---|
797 | if (swd->use_best_off)
|
---|
798 | better_match(swd, &m_len, &m_off);
|
---|
799 | #endif
|
---|
800 |
|
---|
801 | /* shall we try a lazy match ? */
|
---|
802 | ahead = 0;
|
---|
803 | if (m_len >= max_lazy) {
|
---|
804 | /* no */
|
---|
805 | l1 = 0;
|
---|
806 | max_ahead = 0;
|
---|
807 | } else {
|
---|
808 | /* yes, try a lazy match */
|
---|
809 | l1 = len_of_coded_match(m_len, m_off, lit);
|
---|
810 | assert(l1 > 0);
|
---|
811 | max_ahead = LZO_MIN(2, (unsigned)l1 - 1);
|
---|
812 | }
|
---|
813 |
|
---|
814 |
|
---|
815 | while (ahead < max_ahead && c->look > m_len) {
|
---|
816 | int lazy_match_min_gain;
|
---|
817 |
|
---|
818 | if (m_len >= good_length)
|
---|
819 | swd->max_chain = max_chain >> 2;
|
---|
820 | else
|
---|
821 | swd->max_chain = max_chain;
|
---|
822 | r = find_match(c, swd, 1, 0);
|
---|
823 | ahead++;
|
---|
824 |
|
---|
825 | assert(r == 0);
|
---|
826 | assert(c->look > 0);
|
---|
827 | assert(ii + lit + ahead == c->bp);
|
---|
828 |
|
---|
829 | if (c->m_len < m_len)
|
---|
830 | continue;
|
---|
831 | if (c->m_len == m_len && c->m_off >= m_off)
|
---|
832 | continue;
|
---|
833 | #if defined(SWD_BEST_OFF)
|
---|
834 | if (swd->use_best_off)
|
---|
835 | better_match(swd, &c->m_len, &c->m_off);
|
---|
836 | #endif
|
---|
837 | l2 = len_of_coded_match(c->m_len, c->m_off, lit+ahead);
|
---|
838 | if (l2 < 0)
|
---|
839 | continue;
|
---|
840 |
|
---|
841 | /* compressed-data compatibility [see above] */
|
---|
842 | l3 = (op == out) ? -1 : len_of_coded_match(ahead, m_off, lit);
|
---|
843 |
|
---|
844 | lazy_match_min_gain = min_gain(ahead, lit, lit+ahead, l1, l2, l3);
|
---|
845 | if (c->m_len >= m_len + lazy_match_min_gain) {
|
---|
846 | if (l3 > 0) {
|
---|
847 | /* code previous run */
|
---|
848 | op = code_run(c, op, ii, lit);
|
---|
849 | lit = 0;
|
---|
850 | /* code shortened match */
|
---|
851 | op = code_match(c, op, ahead, m_off);
|
---|
852 | } else {
|
---|
853 | lit += ahead;
|
---|
854 | assert(ii + lit == c->bp);
|
---|
855 | }
|
---|
856 | goto lazy_match_done;
|
---|
857 | }
|
---|
858 | }
|
---|
859 |
|
---|
860 | assert(ii + lit + ahead == c->bp);
|
---|
861 |
|
---|
862 | /* 1 - code run */
|
---|
863 | op = code_run(c, op, ii, lit);
|
---|
864 | lit = 0;
|
---|
865 |
|
---|
866 | /* 2 - code match */
|
---|
867 | op = code_match(c, op, m_len, m_off);
|
---|
868 | swd->max_chain = max_chain;
|
---|
869 | r = find_match(c, swd, m_len, 1+ahead);
|
---|
870 | assert(r == 0);
|
---|
871 |
|
---|
872 | lazy_match_done: ;
|
---|
873 | }
|
---|
874 |
|
---|
875 | /* store final run */
|
---|
876 | if (lit > 0)
|
---|
877 | op = STORE_RUN(c, op, ii, lit);
|
---|
878 |
|
---|
879 | #if defined(LZO_EOF_CODE)
|
---|
880 | *op++ = M4_MARKER | 1;
|
---|
881 | *op++ = 0;
|
---|
882 | *op++ = 0;
|
---|
883 | #endif
|
---|
884 |
|
---|
885 | *out_len = op - out;
|
---|
886 |
|
---|
887 | return LZO_E_OK;
|
---|
888 | }
|
---|
889 |
|
---|
890 |
|
---|
891 | /***********************************************************************
|
---|
892 | //
|
---|
893 | ************************************************************************/
|
---|
894 | int lzo1x_999_compress_level(const uint8_t *in, unsigned in_len,
|
---|
895 | uint8_t *out, unsigned *out_len,
|
---|
896 | void *wrkmem,
|
---|
897 | int compression_level)
|
---|
898 | {
|
---|
899 | static const struct {
|
---|
900 | uint16_t good_length;
|
---|
901 | uint16_t max_lazy;
|
---|
902 | uint16_t max_chain;
|
---|
903 | uint16_t use_best_off;
|
---|
904 | } c[3] = {
|
---|
905 | { 8, 32, 256, 0 },
|
---|
906 | { 32, 128, 2048, 1 },
|
---|
907 | { SWD_F, SWD_F, 4096, 1 } /* max. compression */
|
---|
908 | };
|
---|
909 |
|
---|
910 | if (compression_level < 7 || compression_level > 9)
|
---|
911 | return LZO_E_ERROR;
|
---|
912 |
|
---|
913 | compression_level -= 7;
|
---|
914 | return lzo1x_999_compress_internal(in, in_len, out, out_len, wrkmem,
|
---|
915 | c[compression_level].good_length,
|
---|
916 | c[compression_level].max_lazy,
|
---|
917 | c[compression_level].max_chain,
|
---|
918 | c[compression_level].use_best_off);
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919 | }
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