private static OpcodeInfo FindOpcode(PhysicalMemory memory, Processor processor)
{
unsafe
{
uint* eip = (uint*)processor.PIP;
uint startEIP = *eip;
processor.StartEIP = startEIP;
byte* ip = processor.CachedInstruction;
memory.FetchInstruction(processor.segmentBases[(int)SegmentIndex.CS] + startEIP, ip);
byte byte1 = ip[0];
var inst = oneByteCodes[byte1];
if (inst != null)
{
*eip = startEIP + 1;
processor.CachedIP = ip + 1;
return inst;
}
var instSet = twoByteCodes[byte1];
if (instSet != null)
{
inst = instSet[ip[1]];
if (inst != null)
{
*eip = startEIP + 2;
processor.CachedIP = ip + 2;
return inst;
}
}
instSet = rmCodes[byte1];
if (instSet != null)
{
inst = instSet[(ip[1] & ModRmMask) >> 3];
if (inst == null)
ThrowGetOpcodeException(ip);
*eip = startEIP + 1;
processor.CachedIP = ip + 1;
return inst;
}
var instSetSet = twoByteRmCodes[byte1];
if (instSetSet != null)
{
instSet = instSetSet[ip[1]];
if (instSet != null)
{
inst = instSet[(ip[2] & ModRmMask) >> 3];
if (inst != null)
{
*eip = startEIP + 2;
processor.CachedIP = ip + 2;
return inst;
}
}
}
ThrowGetOpcodeException(ip);
return null;
}
}