nel/3rdparty/seven_zip/Bcj2.c

   1 /* Bcj2.c -- BCJ2 Decoder (Converter for x86 code)
   2 2018-04-28 : Igor Pavlov : Public domain */
   3
   4 #include "Precomp.h"
   5
   6 #include "Bcj2.h"
   7 #include "CpuArch.h"
   8
   9 #define CProb UInt16
  10
  11 #define kTopValue ((UInt32)1 << 24)
  12 #define kNumModelBits 11
  13 #define kBitModelTotal (1 << kNumModelBits)
  14 #define kNumMoveBits 5
  15
  16 #define _IF_BIT_0 ttt = *prob; bound = (p->range >> kNumModelBits) * ttt; if (p->code < bound)
  17 #define _UPDATE_0 p->range = bound; *prob = (CProb)(ttt + ((kBitModelTotal - ttt) >> kNumMoveBits));
  18 #define _UPDATE_1 p->range -= bound; p->code -= bound; *prob = (CProb)(ttt - (ttt >> kNumMoveBits));
  19
  20 void Bcj2Dec_Init(CBcj2Dec *p)
  21 {
  22   unsigned i;
  23
  24   p->state = BCJ2_DEC_STATE_OK;
  25   p->ip = 0;
  26   p->temp[3] = 0;
  27   p->range = 0;
  28   p->code = 0;
  29   for (i = 0; i < sizeof(p->probs) / sizeof(p->probs[0]); i++)
  30     p->probs[i] = kBitModelTotal >> 1;
  31 }
  32
  33 SRes Bcj2Dec_Decode(CBcj2Dec *p)
  34 {
  35   if (p->range <= 5)
  36   {
  37     p->state = BCJ2_DEC_STATE_OK;
  38     for (; p->range != 5; p->range++)
  39     {
  40       if (p->range == 1 && p->code != 0)
  41         return SZ_ERROR_DATA;
  42
  43       if (p->bufs[BCJ2_STREAM_RC] == p->lims[BCJ2_STREAM_RC])
  44       {
  45         p->state = BCJ2_STREAM_RC;
  46         return SZ_OK;
  47       }
  48
  49       p->code = (p->code << 8) | *(p->bufs[BCJ2_STREAM_RC])++;
  50     }
  51
  52     if (p->code == 0xFFFFFFFF)
  53       return SZ_ERROR_DATA;
  54
  55     p->range = 0xFFFFFFFF;
  56   }
  57   else if (p->state >= BCJ2_DEC_STATE_ORIG_0)
  58   {
  59     while (p->state <= BCJ2_DEC_STATE_ORIG_3)
  60     {
  61       Byte *dest = p->dest;
  62       if (dest == p->destLim)
  63         return SZ_OK;
  64       *dest = p->temp[(size_t)p->state - BCJ2_DEC_STATE_ORIG_0];
  65       p->state++;
  66       p->dest = dest + 1;
  67     }
  68   }
  69
  70   /*
  71   if (BCJ2_IS_32BIT_STREAM(p->state))
  72   {
  73     const Byte *cur = p->bufs[p->state];
  74     if (cur == p->lims[p->state])
  75       return SZ_OK;
  76     p->bufs[p->state] = cur + 4;
  77
  78     {
  79       UInt32 val;
  80       Byte *dest;
  81       SizeT rem;
  82
  83       p->ip += 4;
  84       val = GetBe32(cur) - p->ip;
  85       dest = p->dest;
  86       rem = p->destLim - dest;
  87       if (rem < 4)
  88       {
  89         SizeT i;
  90         SetUi32(p->temp, val);
  91         for (i = 0; i < rem; i++)
  92           dest[i] = p->temp[i];
  93         p->dest = dest + rem;
  94         p->state = BCJ2_DEC_STATE_ORIG_0 + (unsigned)rem;
  95         return SZ_OK;
  96       }
  97       SetUi32(dest, val);
  98       p->temp[3] = (Byte)(val >> 24);
  99       p->dest = dest + 4;
 100       p->state = BCJ2_DEC_STATE_OK;
 101     }
 102   }
 103   */
 104
 105   for (;;)
 106   {
 107     if (BCJ2_IS_32BIT_STREAM(p->state))
 108       p->state = BCJ2_DEC_STATE_OK;
 109     else
 110     {
 111       if (p->range < kTopValue)
 112       {
 113         if (p->bufs[BCJ2_STREAM_RC] == p->lims[BCJ2_STREAM_RC])
 114         {
 115           p->state = BCJ2_STREAM_RC;
 116           return SZ_OK;
 117         }
 118         p->range <<= 8;
 119         p->code = (p->code << 8) | *(p->bufs[BCJ2_STREAM_RC])++;
 120       }
 121
 122       {
 123         const Byte *src = p->bufs[BCJ2_STREAM_MAIN];
 124         const Byte *srcLim;
 125         Byte *dest;
 126         SizeT num = p->lims[BCJ2_STREAM_MAIN] - src;
 127
 128         if (num == 0)
 129         {
 130           p->state = BCJ2_STREAM_MAIN;
 131           return SZ_OK;
 132         }
 133
 134         dest = p->dest;
 135         if (num > (SizeT)(p->destLim - dest))
 136         {
 137           num = p->destLim - dest;
 138           if (num == 0)
 139           {
 140             p->state = BCJ2_DEC_STATE_ORIG;
 141             return SZ_OK;
 142           }
 143         }
 144
 145         srcLim = src + num;
 146
 147         if (p->temp[3] == 0x0F && (src[0] & 0xF0) == 0x80)
 148           *dest = src[0];
 149         else for (;;)
 150         {
 151           Byte b = *src;
 152           *dest = b;
 153           if (b != 0x0F)
 154           {
 155             if ((b & 0xFE) == 0xE8)
 156               break;
 157             dest++;
 158             if (++src != srcLim)
 159               continue;
 160             break;
 161           }
 162           dest++;
 163           if (++src == srcLim)
 164             break;
 165           if ((*src & 0xF0) != 0x80)
 166             continue;
 167           *dest = *src;
 168           break;
 169         }
 170
 171         num = src - p->bufs[BCJ2_STREAM_MAIN];
 172
 173         if (src == srcLim)
 174         {
 175           p->temp[3] = src[-1];
 176           p->bufs[BCJ2_STREAM_MAIN] = src;
 177           p->ip += (UInt32)num;
 178           p->dest += num;
 179           p->state =
 180             p->bufs[BCJ2_STREAM_MAIN] ==
 181             p->lims[BCJ2_STREAM_MAIN] ?
 182               (unsigned)BCJ2_STREAM_MAIN :
 183               (unsigned)BCJ2_DEC_STATE_ORIG;
 184           return SZ_OK;
 185         }
 186
 187         {
 188           UInt32 bound, ttt;
 189           CProb *prob;
 190           Byte b = src[0];
 191           Byte prev = (Byte)(num == 0 ? p->temp[3] : src[-1]);
 192
 193           p->temp[3] = b;
 194           p->bufs[BCJ2_STREAM_MAIN] = src + 1;
 195           num++;
 196           p->ip += (UInt32)num;
 197           p->dest += num;
 198
 199           prob = p->probs + (unsigned)(b == 0xE8 ? 2 + (unsigned)prev : (b == 0xE9 ? 1 : 0));
 200
 201           _IF_BIT_0
 202           {
 203             _UPDATE_0
 204             continue;
 205           }
 206           _UPDATE_1
 207
 208         }
 209       }
 210     }
 211
 212     {
 213       UInt32 val;
 214       unsigned cj = (p->temp[3] == 0xE8) ? BCJ2_STREAM_CALL : BCJ2_STREAM_JUMP;
 215       const Byte *cur = p->bufs[cj];
 216       Byte *dest;
 217       SizeT rem;
 218
 219       if (cur == p->lims[cj])
 220       {
 221         p->state = cj;
 222         break;
 223       }
 224
 225       val = GetBe32(cur);
 226       p->bufs[cj] = cur + 4;
 227
 228       p->ip += 4;
 229       val -= p->ip;
 230       dest = p->dest;
 231       rem = p->destLim - dest;
 232
 233       if (rem < 4)
 234       {
 235         p->temp[0] = (Byte)val; if (rem > 0) dest[0] = (Byte)val; val >>= 8;
 236         p->temp[1] = (Byte)val; if (rem > 1) dest[1] = (Byte)val; val >>= 8;
 237         p->temp[2] = (Byte)val; if (rem > 2) dest[2] = (Byte)val; val >>= 8;
 238         p->temp[3] = (Byte)val;
 239         p->dest = dest + rem;
 240         p->state = BCJ2_DEC_STATE_ORIG_0 + (unsigned)rem;
 241         break;
 242       }
 243
 244       SetUi32(dest, val);
 245       p->temp[3] = (Byte)(val >> 24);
 246       p->dest = dest + 4;
 247     }
 248   }
 249
 250   if (p->range < kTopValue && p->bufs[BCJ2_STREAM_RC] != p->lims[BCJ2_STREAM_RC])
 251   {
 252     p->range <<= 8;
 253     p->code = (p->code << 8) | *(p->bufs[BCJ2_STREAM_RC])++;
 254   }
 255
 256   return SZ_OK;
 257 }