ref: 2c9e3861a54e22498fb2e3226defe4393b20b202
dir: /sys/src/libc/386/getfcr.s/
TEXT setfcr(SB), $4 MOVL p+0(FP),AX XORB $0x3f,AX MOVW AX, 0(SP) WAIT FLDCW 0(SP) MOVW 0(SP), AX RET TEXT getfcr(SB), $4 MOVW AX, 0(SP) WAIT FSTCW 0(SP) MOVW 0(SP), AX XORB $0x3f,AX RET TEXT getfsr(SB), $0 WAIT FSTSW AX RET TEXT setfsr(SB), $0 WAIT FCLEX RET