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/* BranchX86.c */
#include "BranchX86.h"
/*
static int inline Test86MSByte(Byte b)
{
return (b == 0 || b == 0xFF);
}
*/
#define Test86MSByte(b) ((b) == 0 || (b) == 0xFF)
const int kMaskToAllowedStatus[8] = {1, 1, 1, 0, 1, 0, 0, 0};
const Byte kMaskToBitNumber[8] = {0, 1, 2, 2, 3, 3, 3, 3};
/*
void x86_Convert_Init(UInt32 *prevMask, UInt32 *prevPos)
{
*prevMask = 0;
*prevPos = (UInt32)(-5);
}
*/
UInt32 x86_Convert(Byte *buffer, UInt32 endPos, UInt32 nowPos,
UInt32 *prevMask, UInt32 *prevPos, int encoding)
{
UInt32 bufferPos = 0;
UInt32 limit;
if (endPos < 5)
return 0;
if (nowPos - *prevPos > 5)
*prevPos = nowPos - 5;
limit = endPos - 5;
while(bufferPos <= limit)
{
Byte b = buffer[bufferPos];
UInt32 offset;
if (b != 0xE8 && b != 0xE9)
{
bufferPos++;
continue;
}
offset = (nowPos + bufferPos - *prevPos);
*prevPos = (nowPos + bufferPos);
if (offset > 5)
*prevMask = 0;
else
{
UInt32 i;
for (i = 0; i < offset; i++)
{
*prevMask &= 0x77;
*prevMask <<= 1;
}
}
b = buffer[bufferPos + 4];
if (Test86MSByte(b) && kMaskToAllowedStatus[(*prevMask >> 1) & 0x7] &&
(*prevMask >> 1) < 0x10)
{
UInt32 src =
((UInt32)(b) << 24) |
((UInt32)(buffer[bufferPos + 3]) << 16) |
((UInt32)(buffer[bufferPos + 2]) << 8) |
(buffer[bufferPos + 1]);
UInt32 dest;
while(1)
{
UInt32 index;
if (encoding)
dest = (nowPos + bufferPos + 5) + src;
else
dest = src - (nowPos + bufferPos + 5);
if (*prevMask == 0)
break;
index = kMaskToBitNumber[*prevMask >> 1];
b = (Byte)(dest >> (24 - index * 8));
if (!Test86MSByte(b))
break;
src = dest ^ ((1 << (32 - index * 8)) - 1);
}
buffer[bufferPos + 4] = (Byte)(~(((dest >> 24) & 1) - 1));
buffer[bufferPos + 3] = (Byte)(dest >> 16);
buffer[bufferPos + 2] = (Byte)(dest >> 8);
buffer[bufferPos + 1] = (Byte)dest;
bufferPos += 5;
*prevMask = 0;
}
else
{
bufferPos++;
*prevMask |= 1;
if (Test86MSByte(b))
*prevMask |= 0x10;
}
}
return bufferPos;
}
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