| 1 | /* Bcj2.c -- BCJ2 Decoder (Converter for x86 code)\r |
| 2 | 2021-02-09 : Igor Pavlov : Public domain */\r |
| 3 | \r |
| 4 | #include "Precomp.h"\r |
| 5 | \r |
| 6 | #include "Bcj2.h"\r |
| 7 | #include "CpuArch.h"\r |
| 8 | \r |
| 9 | #define CProb UInt16\r |
| 10 | \r |
| 11 | #define kTopValue ((UInt32)1 << 24)\r |
| 12 | #define kNumModelBits 11\r |
| 13 | #define kBitModelTotal (1 << kNumModelBits)\r |
| 14 | #define kNumMoveBits 5\r |
| 15 | \r |
| 16 | #define _IF_BIT_0 ttt = *prob; bound = (p->range >> kNumModelBits) * ttt; if (p->code < bound)\r |
| 17 | #define _UPDATE_0 p->range = bound; *prob = (CProb)(ttt + ((kBitModelTotal - ttt) >> kNumMoveBits));\r |
| 18 | #define _UPDATE_1 p->range -= bound; p->code -= bound; *prob = (CProb)(ttt - (ttt >> kNumMoveBits));\r |
| 19 | \r |
| 20 | void Bcj2Dec_Init(CBcj2Dec *p)\r |
| 21 | {\r |
| 22 | unsigned i;\r |
| 23 | \r |
| 24 | p->state = BCJ2_DEC_STATE_OK;\r |
| 25 | p->ip = 0;\r |
| 26 | p->temp[3] = 0;\r |
| 27 | p->range = 0;\r |
| 28 | p->code = 0;\r |
| 29 | for (i = 0; i < sizeof(p->probs) / sizeof(p->probs[0]); i++)\r |
| 30 | p->probs[i] = kBitModelTotal >> 1;\r |
| 31 | }\r |
| 32 | \r |
| 33 | SRes Bcj2Dec_Decode(CBcj2Dec *p)\r |
| 34 | {\r |
| 35 | if (p->range <= 5)\r |
| 36 | {\r |
| 37 | p->state = BCJ2_DEC_STATE_OK;\r |
| 38 | for (; p->range != 5; p->range++)\r |
| 39 | {\r |
| 40 | if (p->range == 1 && p->code != 0)\r |
| 41 | return SZ_ERROR_DATA;\r |
| 42 | \r |
| 43 | if (p->bufs[BCJ2_STREAM_RC] == p->lims[BCJ2_STREAM_RC])\r |
| 44 | {\r |
| 45 | p->state = BCJ2_STREAM_RC;\r |
| 46 | return SZ_OK;\r |
| 47 | }\r |
| 48 | \r |
| 49 | p->code = (p->code << 8) | *(p->bufs[BCJ2_STREAM_RC])++;\r |
| 50 | }\r |
| 51 | \r |
| 52 | if (p->code == 0xFFFFFFFF)\r |
| 53 | return SZ_ERROR_DATA;\r |
| 54 | \r |
| 55 | p->range = 0xFFFFFFFF;\r |
| 56 | }\r |
| 57 | else if (p->state >= BCJ2_DEC_STATE_ORIG_0)\r |
| 58 | {\r |
| 59 | while (p->state <= BCJ2_DEC_STATE_ORIG_3)\r |
| 60 | {\r |
| 61 | Byte *dest = p->dest;\r |
| 62 | if (dest == p->destLim)\r |
| 63 | return SZ_OK;\r |
| 64 | *dest = p->temp[(size_t)p->state - BCJ2_DEC_STATE_ORIG_0];\r |
| 65 | p->state++;\r |
| 66 | p->dest = dest + 1;\r |
| 67 | }\r |
| 68 | }\r |
| 69 | \r |
| 70 | /*\r |
| 71 | if (BCJ2_IS_32BIT_STREAM(p->state))\r |
| 72 | {\r |
| 73 | const Byte *cur = p->bufs[p->state];\r |
| 74 | if (cur == p->lims[p->state])\r |
| 75 | return SZ_OK;\r |
| 76 | p->bufs[p->state] = cur + 4;\r |
| 77 | \r |
| 78 | {\r |
| 79 | UInt32 val;\r |
| 80 | Byte *dest;\r |
| 81 | SizeT rem;\r |
| 82 | \r |
| 83 | p->ip += 4;\r |
| 84 | val = GetBe32(cur) - p->ip;\r |
| 85 | dest = p->dest;\r |
| 86 | rem = p->destLim - dest;\r |
| 87 | if (rem < 4)\r |
| 88 | {\r |
| 89 | SizeT i;\r |
| 90 | SetUi32(p->temp, val);\r |
| 91 | for (i = 0; i < rem; i++)\r |
| 92 | dest[i] = p->temp[i];\r |
| 93 | p->dest = dest + rem;\r |
| 94 | p->state = BCJ2_DEC_STATE_ORIG_0 + (unsigned)rem;\r |
| 95 | return SZ_OK;\r |
| 96 | }\r |
| 97 | SetUi32(dest, val);\r |
| 98 | p->temp[3] = (Byte)(val >> 24);\r |
| 99 | p->dest = dest + 4;\r |
| 100 | p->state = BCJ2_DEC_STATE_OK;\r |
| 101 | }\r |
| 102 | }\r |
| 103 | */\r |
| 104 | \r |
| 105 | for (;;)\r |
| 106 | {\r |
| 107 | if (BCJ2_IS_32BIT_STREAM(p->state))\r |
| 108 | p->state = BCJ2_DEC_STATE_OK;\r |
| 109 | else\r |
| 110 | {\r |
| 111 | if (p->range < kTopValue)\r |
| 112 | {\r |
| 113 | if (p->bufs[BCJ2_STREAM_RC] == p->lims[BCJ2_STREAM_RC])\r |
| 114 | {\r |
| 115 | p->state = BCJ2_STREAM_RC;\r |
| 116 | return SZ_OK;\r |
| 117 | }\r |
| 118 | p->range <<= 8;\r |
| 119 | p->code = (p->code << 8) | *(p->bufs[BCJ2_STREAM_RC])++;\r |
| 120 | }\r |
| 121 | \r |
| 122 | {\r |
| 123 | const Byte *src = p->bufs[BCJ2_STREAM_MAIN];\r |
| 124 | const Byte *srcLim;\r |
| 125 | Byte *dest;\r |
| 126 | SizeT num = (SizeT)(p->lims[BCJ2_STREAM_MAIN] - src);\r |
| 127 | \r |
| 128 | if (num == 0)\r |
| 129 | {\r |
| 130 | p->state = BCJ2_STREAM_MAIN;\r |
| 131 | return SZ_OK;\r |
| 132 | }\r |
| 133 | \r |
| 134 | dest = p->dest;\r |
| 135 | if (num > (SizeT)(p->destLim - dest))\r |
| 136 | {\r |
| 137 | num = (SizeT)(p->destLim - dest);\r |
| 138 | if (num == 0)\r |
| 139 | {\r |
| 140 | p->state = BCJ2_DEC_STATE_ORIG;\r |
| 141 | return SZ_OK;\r |
| 142 | }\r |
| 143 | }\r |
| 144 | \r |
| 145 | srcLim = src + num;\r |
| 146 | \r |
| 147 | if (p->temp[3] == 0x0F && (src[0] & 0xF0) == 0x80)\r |
| 148 | *dest = src[0];\r |
| 149 | else for (;;)\r |
| 150 | {\r |
| 151 | Byte b = *src;\r |
| 152 | *dest = b;\r |
| 153 | if (b != 0x0F)\r |
| 154 | {\r |
| 155 | if ((b & 0xFE) == 0xE8)\r |
| 156 | break;\r |
| 157 | dest++;\r |
| 158 | if (++src != srcLim)\r |
| 159 | continue;\r |
| 160 | break;\r |
| 161 | }\r |
| 162 | dest++;\r |
| 163 | if (++src == srcLim)\r |
| 164 | break;\r |
| 165 | if ((*src & 0xF0) != 0x80)\r |
| 166 | continue;\r |
| 167 | *dest = *src;\r |
| 168 | break;\r |
| 169 | }\r |
| 170 | \r |
| 171 | num = (SizeT)(src - p->bufs[BCJ2_STREAM_MAIN]);\r |
| 172 | \r |
| 173 | if (src == srcLim)\r |
| 174 | {\r |
| 175 | p->temp[3] = src[-1];\r |
| 176 | p->bufs[BCJ2_STREAM_MAIN] = src;\r |
| 177 | p->ip += (UInt32)num;\r |
| 178 | p->dest += num;\r |
| 179 | p->state =\r |
| 180 | p->bufs[BCJ2_STREAM_MAIN] ==\r |
| 181 | p->lims[BCJ2_STREAM_MAIN] ?\r |
| 182 | (unsigned)BCJ2_STREAM_MAIN :\r |
| 183 | (unsigned)BCJ2_DEC_STATE_ORIG;\r |
| 184 | return SZ_OK;\r |
| 185 | }\r |
| 186 | \r |
| 187 | {\r |
| 188 | UInt32 bound, ttt;\r |
| 189 | CProb *prob;\r |
| 190 | Byte b = src[0];\r |
| 191 | Byte prev = (Byte)(num == 0 ? p->temp[3] : src[-1]);\r |
| 192 | \r |
| 193 | p->temp[3] = b;\r |
| 194 | p->bufs[BCJ2_STREAM_MAIN] = src + 1;\r |
| 195 | num++;\r |
| 196 | p->ip += (UInt32)num;\r |
| 197 | p->dest += num;\r |
| 198 | \r |
| 199 | prob = p->probs + (unsigned)(b == 0xE8 ? 2 + (unsigned)prev : (b == 0xE9 ? 1 : 0));\r |
| 200 | \r |
| 201 | _IF_BIT_0\r |
| 202 | {\r |
| 203 | _UPDATE_0\r |
| 204 | continue;\r |
| 205 | }\r |
| 206 | _UPDATE_1\r |
| 207 | \r |
| 208 | }\r |
| 209 | }\r |
| 210 | }\r |
| 211 | \r |
| 212 | {\r |
| 213 | UInt32 val;\r |
| 214 | unsigned cj = (p->temp[3] == 0xE8) ? BCJ2_STREAM_CALL : BCJ2_STREAM_JUMP;\r |
| 215 | const Byte *cur = p->bufs[cj];\r |
| 216 | Byte *dest;\r |
| 217 | SizeT rem;\r |
| 218 | \r |
| 219 | if (cur == p->lims[cj])\r |
| 220 | {\r |
| 221 | p->state = cj;\r |
| 222 | break;\r |
| 223 | }\r |
| 224 | \r |
| 225 | val = GetBe32(cur);\r |
| 226 | p->bufs[cj] = cur + 4;\r |
| 227 | \r |
| 228 | p->ip += 4;\r |
| 229 | val -= p->ip;\r |
| 230 | dest = p->dest;\r |
| 231 | rem = (SizeT)(p->destLim - dest);\r |
| 232 | \r |
| 233 | if (rem < 4)\r |
| 234 | {\r |
| 235 | p->temp[0] = (Byte)val; if (rem > 0) dest[0] = (Byte)val; val >>= 8;\r |
| 236 | p->temp[1] = (Byte)val; if (rem > 1) dest[1] = (Byte)val; val >>= 8;\r |
| 237 | p->temp[2] = (Byte)val; if (rem > 2) dest[2] = (Byte)val; val >>= 8;\r |
| 238 | p->temp[3] = (Byte)val;\r |
| 239 | p->dest = dest + rem;\r |
| 240 | p->state = BCJ2_DEC_STATE_ORIG_0 + (unsigned)rem;\r |
| 241 | break;\r |
| 242 | }\r |
| 243 | \r |
| 244 | SetUi32(dest, val);\r |
| 245 | p->temp[3] = (Byte)(val >> 24);\r |
| 246 | p->dest = dest + 4;\r |
| 247 | }\r |
| 248 | }\r |
| 249 | \r |
| 250 | if (p->range < kTopValue && p->bufs[BCJ2_STREAM_RC] != p->lims[BCJ2_STREAM_RC])\r |
| 251 | {\r |
| 252 | p->range <<= 8;\r |
| 253 | p->code = (p->code << 8) | *(p->bufs[BCJ2_STREAM_RC])++;\r |
| 254 | }\r |
| 255 | \r |
| 256 | return SZ_OK;\r |
| 257 | }\r |