ref: 249dc0489c7b24371e1f829e9c849fa7464f6c0c
dir: /os/pc/fpsave.s/
TEXT FPsave(SB), 1, $0 /* save FPU environment without waiting */ MOVL fpu+0(FP), AX FSTENV 0(AX) RET TEXT FPrestore(SB), 1, $0 /* restore FPU environment without waiting */ MOVL fpu+0(FP), AX FLDENV 0(AX) RET