| /* Bcj2.c -- BCJ2 Decoder (Converter for x86 code) |
| 2015-08-01 : Igor Pavlov : Public domain */ |
| |
| #include "Precomp.h" |
| |
| #include "Bcj2.h" |
| #include "CpuArch.h" |
| |
| #define CProb UInt16 |
| |
| #define kTopValue ((UInt32)1 << 24) |
| #define kNumModelBits 11 |
| #define kBitModelTotal (1 << kNumModelBits) |
| #define kNumMoveBits 5 |
| |
| #define _IF_BIT_0 ttt = *prob; bound = (p->range >> kNumModelBits) * ttt; if (p->code < bound) |
| #define _UPDATE_0 p->range = bound; *prob = (CProb)(ttt + ((kBitModelTotal - ttt) >> kNumMoveBits)); |
| #define _UPDATE_1 p->range -= bound; p->code -= bound; *prob = (CProb)(ttt - (ttt >> kNumMoveBits)); |
| |
| void Bcj2Dec_Init(CBcj2Dec *p) |
| { |
| unsigned i; |
| |
| p->state = BCJ2_DEC_STATE_OK; |
| p->ip = 0; |
| p->temp[3] = 0; |
| p->range = 0; |
| p->code = 0; |
| for (i = 0; i < sizeof(p->probs) / sizeof(p->probs[0]); i++) |
| p->probs[i] = kBitModelTotal >> 1; |
| } |
| |
| SRes Bcj2Dec_Decode(CBcj2Dec *p) |
| { |
| if (p->range <= 5) |
| { |
| p->state = BCJ2_DEC_STATE_OK; |
| for (; p->range != 5; p->range++) |
| { |
| if (p->range == 1 && p->code != 0) |
| return SZ_ERROR_DATA; |
| |
| if (p->bufs[BCJ2_STREAM_RC] == p->lims[BCJ2_STREAM_RC]) |
| { |
| p->state = BCJ2_STREAM_RC; |
| return SZ_OK; |
| } |
| |
| p->code = (p->code << 8) | *(p->bufs[BCJ2_STREAM_RC])++; |
| } |
| |
| if (p->code == 0xFFFFFFFF) |
| return SZ_ERROR_DATA; |
| |
| p->range = 0xFFFFFFFF; |
| } |
| else if (p->state >= BCJ2_DEC_STATE_ORIG_0) |
| { |
| while (p->state <= BCJ2_DEC_STATE_ORIG_3) |
| { |
| Byte *dest = p->dest; |
| if (dest == p->destLim) |
| return SZ_OK; |
| *dest = p->temp[p->state++ - BCJ2_DEC_STATE_ORIG_0]; |
| p->dest = dest + 1; |
| } |
| } |
| |
| /* |
| if (BCJ2_IS_32BIT_STREAM(p->state)) |
| { |
| const Byte *cur = p->bufs[p->state]; |
| if (cur == p->lims[p->state]) |
| return SZ_OK; |
| p->bufs[p->state] = cur + 4; |
| |
| { |
| UInt32 val; |
| Byte *dest; |
| SizeT rem; |
| |
| p->ip += 4; |
| val = GetBe32(cur) - p->ip; |
| dest = p->dest; |
| rem = p->destLim - dest; |
| if (rem < 4) |
| { |
| SizeT i; |
| SetUi32(p->temp, val); |
| for (i = 0; i < rem; i++) |
| dest[i] = p->temp[i]; |
| p->dest = dest + rem; |
| p->state = BCJ2_DEC_STATE_ORIG_0 + (unsigned)rem; |
| return SZ_OK; |
| } |
| SetUi32(dest, val); |
| p->temp[3] = (Byte)(val >> 24); |
| p->dest = dest + 4; |
| p->state = BCJ2_DEC_STATE_OK; |
| } |
| } |
| */ |
| |
| for (;;) |
| { |
| if (BCJ2_IS_32BIT_STREAM(p->state)) |
| p->state = BCJ2_DEC_STATE_OK; |
| else |
| { |
| if (p->range < kTopValue) |
| { |
| if (p->bufs[BCJ2_STREAM_RC] == p->lims[BCJ2_STREAM_RC]) |
| { |
| p->state = BCJ2_STREAM_RC; |
| return SZ_OK; |
| } |
| p->range <<= 8; |
| p->code = (p->code << 8) | *(p->bufs[BCJ2_STREAM_RC])++; |
| } |
| |
| { |
| const Byte *src = p->bufs[BCJ2_STREAM_MAIN]; |
| const Byte *srcLim; |
| Byte *dest; |
| SizeT num = p->lims[BCJ2_STREAM_MAIN] - src; |
| |
| if (num == 0) |
| { |
| p->state = BCJ2_STREAM_MAIN; |
| return SZ_OK; |
| } |
| |
| dest = p->dest; |
| if (num > (SizeT)(p->destLim - dest)) |
| { |
| num = p->destLim - dest; |
| if (num == 0) |
| { |
| p->state = BCJ2_DEC_STATE_ORIG; |
| return SZ_OK; |
| } |
| } |
| |
| srcLim = src + num; |
| |
| if (p->temp[3] == 0x0F && (src[0] & 0xF0) == 0x80) |
| *dest = src[0]; |
| else for (;;) |
| { |
| Byte b = *src; |
| *dest = b; |
| if (b != 0x0F) |
| { |
| if ((b & 0xFE) == 0xE8) |
| break; |
| dest++; |
| if (++src != srcLim) |
| continue; |
| break; |
| } |
| dest++; |
| if (++src == srcLim) |
| break; |
| if ((*src & 0xF0) != 0x80) |
| continue; |
| *dest = *src; |
| break; |
| } |
| |
| num = src - p->bufs[BCJ2_STREAM_MAIN]; |
| |
| if (src == srcLim) |
| { |
| p->temp[3] = src[-1]; |
| p->bufs[BCJ2_STREAM_MAIN] = src; |
| p->ip += (UInt32)num; |
| p->dest += num; |
| p->state = |
| p->bufs[BCJ2_STREAM_MAIN] == |
| p->lims[BCJ2_STREAM_MAIN] ? |
| (unsigned)BCJ2_STREAM_MAIN : |
| (unsigned)BCJ2_DEC_STATE_ORIG; |
| return SZ_OK; |
| } |
| |
| { |
| UInt32 bound, ttt; |
| CProb *prob; |
| Byte b = src[0]; |
| Byte prev = (Byte)(num == 0 ? p->temp[3] : src[-1]); |
| |
| p->temp[3] = b; |
| p->bufs[BCJ2_STREAM_MAIN] = src + 1; |
| num++; |
| p->ip += (UInt32)num; |
| p->dest += num; |
| |
| prob = p->probs + (unsigned)(b == 0xE8 ? 2 + (unsigned)prev : (b == 0xE9 ? 1 : 0)); |
| |
| _IF_BIT_0 |
| { |
| _UPDATE_0 |
| continue; |
| } |
| _UPDATE_1 |
| |
| } |
| } |
| } |
| |
| { |
| UInt32 val; |
| unsigned cj = (p->temp[3] == 0xE8) ? BCJ2_STREAM_CALL : BCJ2_STREAM_JUMP; |
| const Byte *cur = p->bufs[cj]; |
| Byte *dest; |
| SizeT rem; |
| |
| if (cur == p->lims[cj]) |
| { |
| p->state = cj; |
| break; |
| } |
| |
| val = GetBe32(cur); |
| p->bufs[cj] = cur + 4; |
| |
| p->ip += 4; |
| val -= p->ip; |
| dest = p->dest; |
| rem = p->destLim - dest; |
| |
| if (rem < 4) |
| { |
| SizeT i; |
| SetUi32(p->temp, val); |
| for (i = 0; i < rem; i++) |
| dest[i] = p->temp[i]; |
| p->dest = dest + rem; |
| p->state = BCJ2_DEC_STATE_ORIG_0 + (unsigned)rem; |
| break; |
| } |
| |
| SetUi32(dest, val); |
| p->temp[3] = (Byte)(val >> 24); |
| p->dest = dest + 4; |
| } |
| } |
| |
| if (p->range < kTopValue && p->bufs[BCJ2_STREAM_RC] != p->lims[BCJ2_STREAM_RC]) |
| { |
| p->range <<= 8; |
| p->code = (p->code << 8) | *(p->bufs[BCJ2_STREAM_RC])++; |
| } |
| |
| return SZ_OK; |
| } |