ref: a3cd9d6083f95a7442935c6f623c7655447215a4
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