_scan_three_integers PROC
MOV EAX,[ESP + 4] ' EAX = p1
ADD EAX,-1
SBB EAX,EAX 'EAX = (p1 != 0) ? -1 : 0
ADD EAX,EAX 'EAX = (p1 != 0) ? -2 : 0
MOV ECX,[ESP + 8] 'ECX = p2
ADD ECX,-1
SBB ECX,ECX 'ECX = (p2 != 0) ? -1 : 0
AND ECX,EAX 'ECX = (p1 != 0) ? -2 : ((p2 != 0) ? -1 : 0)
MOV EAX,ECX
SHL EAX,5
ADD EAX,95 'EAX = (p1 != 0) ? 31 : ((p2 != 0) ? 63 : 95)
BSR EDX, [ESP + 12 + ECX * 4]
SUB EAX,EDX
RET
_scan_three_integers ENDP
速いかどうかはわからんがこういう方向もあり