mirror of
https://github.com/ZDoom/gzdoom.git
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132 lines
3.2 KiB
C
132 lines
3.2 KiB
C
/* Bcj2.c -- Converter for x86 code (BCJ2)
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2008-10-04 : Igor Pavlov : Public domain */
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#include "Bcj2.h"
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#ifdef _LZMA_PROB32
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#define CProb UInt32
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#else
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#define CProb UInt16
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#endif
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#define IsJcc(b0, b1) ((b0) == 0x0F && ((b1) & 0xF0) == 0x80)
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#define IsJ(b0, b1) ((b1 & 0xFE) == 0xE8 || IsJcc(b0, b1))
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#define kNumTopBits 24
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#define kTopValue ((UInt32)1 << kNumTopBits)
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#define kNumBitModelTotalBits 11
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#define kBitModelTotal (1 << kNumBitModelTotalBits)
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#define kNumMoveBits 5
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#define RC_READ_BYTE (*buffer++)
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#define RC_TEST { if (buffer == bufferLim) return SZ_ERROR_DATA; }
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#define RC_INIT2 code = 0; range = 0xFFFFFFFF; \
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{ int i; for (i = 0; i < 5; i++) { RC_TEST; code = (code << 8) | RC_READ_BYTE; }}
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#define NORMALIZE if (range < kTopValue) { RC_TEST; range <<= 8; code = (code << 8) | RC_READ_BYTE; }
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#define IF_BIT_0(p) ttt = *(p); bound = (range >> kNumBitModelTotalBits) * ttt; if (code < bound)
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#define UPDATE_0(p) range = bound; *(p) = (CProb)(ttt + ((kBitModelTotal - ttt) >> kNumMoveBits)); NORMALIZE;
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#define UPDATE_1(p) range -= bound; code -= bound; *(p) = (CProb)(ttt - (ttt >> kNumMoveBits)); NORMALIZE;
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int Bcj2_Decode(
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const Byte *buf0, SizeT size0,
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const Byte *buf1, SizeT size1,
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const Byte *buf2, SizeT size2,
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const Byte *buf3, SizeT size3,
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Byte *outBuf, SizeT outSize)
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{
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CProb p[256 + 2];
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SizeT inPos = 0, outPos = 0;
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const Byte *buffer, *bufferLim;
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UInt32 range, code;
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Byte prevByte = 0;
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unsigned int i;
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for (i = 0; i < sizeof(p) / sizeof(p[0]); i++)
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p[i] = kBitModelTotal >> 1;
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buffer = buf3;
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bufferLim = buffer + size3;
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RC_INIT2
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if (outSize == 0)
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return SZ_OK;
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for (;;)
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{
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Byte b;
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CProb *prob;
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UInt32 bound;
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UInt32 ttt;
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SizeT limit = size0 - inPos;
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if (outSize - outPos < limit)
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limit = outSize - outPos;
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while (limit != 0)
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{
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Byte b = buf0[inPos];
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outBuf[outPos++] = b;
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if (IsJ(prevByte, b))
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break;
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inPos++;
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prevByte = b;
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limit--;
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}
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if (limit == 0 || outPos == outSize)
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break;
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b = buf0[inPos++];
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if (b == 0xE8)
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prob = p + prevByte;
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else if (b == 0xE9)
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prob = p + 256;
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else
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prob = p + 257;
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IF_BIT_0(prob)
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{
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UPDATE_0(prob)
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prevByte = b;
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}
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else
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{
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UInt32 dest;
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const Byte *v;
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UPDATE_1(prob)
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if (b == 0xE8)
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{
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v = buf1;
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if (size1 < 4)
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return SZ_ERROR_DATA;
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buf1 += 4;
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size1 -= 4;
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}
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else
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{
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v = buf2;
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if (size2 < 4)
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return SZ_ERROR_DATA;
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buf2 += 4;
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size2 -= 4;
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}
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dest = (((UInt32)v[0] << 24) | ((UInt32)v[1] << 16) |
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((UInt32)v[2] << 8) | ((UInt32)v[3])) - ((UInt32)outPos + 4);
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outBuf[outPos++] = (Byte)dest;
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if (outPos == outSize)
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break;
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outBuf[outPos++] = (Byte)(dest >> 8);
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if (outPos == outSize)
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break;
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outBuf[outPos++] = (Byte)(dest >> 16);
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if (outPos == outSize)
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break;
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outBuf[outPos++] = prevByte = (Byte)(dest >> 24);
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}
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}
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return (outPos == outSize) ? SZ_OK : SZ_ERROR_DATA;
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}
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