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/* 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++;
}
}
}
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