x86 optable reference
---------------------
(incomplete)
P - modrm (reg mmx)
PR - modrm (rm mmx, mod must be 11b)
Q - modrm (rm mmx if mod=11b else mem)
V - modrm (reg - xmm)
VR - modrm (rm xmm, mod must be 11b)
W - modrm (rm xmm if mod=11b else mem)
G - modrm (reg - gpr)
S - modrm (reg - seg)
VR - modrm (rm gpr, mod must be 11b)
E - modrm (rm gpr if mod=11b else mem)
M - modrm (mem), mod!=11b
I - immediate
J - relative immediate
O - memory offset
C - control reg
D - debug reg
opc <>
/n - modrm reg field extends opcode
/Mnn - disassembly mode extends opcode
/Onn - operand mode extends opcode
/mod=!11 - modrm mod field extends opcode
