/* Bra86.c -- Converter for x86 code (BCJ) | |
2017-04-03 : Igor Pavlov : Public domain */ | |
#include "Precomp.h" | |
#include "Bra.h" | |
#define Test86MSByte(b) ((((b) + 1) & 0xFE) == 0) | |
SizeT | |
x86_Convert ( | |
Byte *data, | |
SizeT size, | |
UInt32 ip, | |
UInt32 *state, | |
int encoding | |
) | |
{ | |
SizeT pos = 0; | |
UInt32 mask = *state & 7; | |
if (size < 5) { | |
return 0; | |
} | |
size -= 4; | |
ip += 5; | |
for ( ; ;) { | |
Byte *p = data + pos; | |
const Byte *limit = data + size; | |
for ( ; p < limit; p++) { | |
if ((*p & 0xFE) == 0xE8) { | |
break; | |
} | |
} | |
{ | |
SizeT d = (SizeT)(p - data - pos); | |
pos = (SizeT)(p - data); | |
if (p >= limit) { | |
*state = (d > 2 ? 0 : mask >> (unsigned)d); | |
return pos; | |
} | |
if (d > 2) { | |
mask = 0; | |
} else { | |
mask >>= (unsigned)d; | |
if ((mask != 0) && ((mask > 4) || (mask == 3) || Test86MSByte (p[(size_t)(mask >> 1) + 1]))) { | |
mask = (mask >> 1) | 4; | |
pos++; | |
continue; | |
} | |
} | |
} | |
if (Test86MSByte (p[4])) { | |
UInt32 v = ((UInt32)p[4] << 24) | ((UInt32)p[3] << 16) | ((UInt32)p[2] << 8) | ((UInt32)p[1]); | |
UInt32 cur = ip + (UInt32)pos; | |
pos += 5; | |
if (encoding) { | |
v += cur; | |
} else { | |
v -= cur; | |
} | |
if (mask != 0) { | |
unsigned sh = (mask & 6) << 2; | |
if (Test86MSByte ((Byte)(v >> sh))) { | |
v ^= (((UInt32)0x100 << sh) - 1); | |
if (encoding) { | |
v += cur; | |
} else { | |
v -= cur; | |
} | |
} | |
mask = 0; | |
} | |
p[1] = (Byte)v; | |
p[2] = (Byte)(v >> 8); | |
p[3] = (Byte)(v >> 16); | |
p[4] = (Byte)(0 - ((v >> 24) & 1)); | |
} else { | |
mask = (mask >> 1) | 4; | |
pos++; | |
} | |
} | |
} |