paddq (64bit + 64bit = 64bit):
movq mm7, mmc
paddd mmc, mma
psubd mm7, 0x80000000
psubd mmc, 0x80000000
pcmpgtd mm7, mmc
paddd mmc, 0x80000000
psllq mm7, 32
psubd mmc, mm7
Niels Fröhling about the vast in the small, and then sometimes [X]HTML, JS and technical tidbits