diff options
Diffstat (limited to 'src/lib/lib7z/Bra86.c')
-rw-r--r-- | src/lib/lib7z/Bra86.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/src/lib/lib7z/Bra86.c b/src/lib/lib7z/Bra86.c new file mode 100644 index 00000000000..1ee0e709b88 --- /dev/null +++ b/src/lib/lib7z/Bra86.c @@ -0,0 +1,85 @@ +/* Bra86.c -- Converter for x86 code (BCJ) +2008-10-04 : Igor Pavlov : Public domain */ + +#include "Bra.h" + +#define Test86MSByte(b) ((b) == 0 || (b) == 0xFF) + +const Byte kMaskToAllowedStatus[8] = {1, 1, 1, 0, 1, 0, 0, 0}; +const Byte kMaskToBitNumber[8] = {0, 1, 2, 2, 3, 3, 3, 3}; + +SizeT x86_Convert(Byte *data, SizeT size, UInt32 ip, UInt32 *state, int encoding) +{ + SizeT bufferPos = 0, prevPosT; + UInt32 prevMask = *state & 0x7; + if (size < 5) + return 0; + ip += 5; + prevPosT = (SizeT)0 - 1; + + for (;;) + { + Byte *p = data + bufferPos; + Byte *limit = data + size - 4; + for (; p < limit; p++) + if ((*p & 0xFE) == 0xE8) + break; + bufferPos = (SizeT)(p - data); + if (p >= limit) + break; + prevPosT = bufferPos - prevPosT; + if (prevPosT > 3) + prevMask = 0; + else + { + prevMask = (prevMask << ((int)prevPosT - 1)) & 0x7; + if (prevMask != 0) + { + Byte b = p[4 - kMaskToBitNumber[prevMask]]; + if (!kMaskToAllowedStatus[prevMask] || Test86MSByte(b)) + { + prevPosT = bufferPos; + prevMask = ((prevMask << 1) & 0x7) | 1; + bufferPos++; + continue; + } + } + } + prevPosT = bufferPos; + + if (Test86MSByte(p[4])) + { + UInt32 src = ((UInt32)p[4] << 24) | ((UInt32)p[3] << 16) | ((UInt32)p[2] << 8) | ((UInt32)p[1]); + UInt32 dest; + for (;;) + { + Byte b; + int index; + if (encoding) + dest = (ip + (UInt32)bufferPos) + src; + else + dest = src - (ip + (UInt32)bufferPos); + if (prevMask == 0) + break; + index = kMaskToBitNumber[prevMask] * 8; + b = (Byte)(dest >> (24 - index)); + if (!Test86MSByte(b)) + break; + src = dest ^ ((1 << (32 - index)) - 1); + } + p[4] = (Byte)(~(((dest >> 24) & 1) - 1)); + p[3] = (Byte)(dest >> 16); + p[2] = (Byte)(dest >> 8); + p[1] = (Byte)dest; + bufferPos += 5; + } + else + { + prevMask = ((prevMask << 1) & 0x7) | 1; + bufferPos++; + } + } + prevPosT = bufferPos - prevPosT; + *state = ((prevPosT > 3) ? 0 : ((prevMask << ((int)prevPosT - 1)) & 0x7)); + return bufferPos; +} |