ref: 79e24f5ee56c7abc31942615e587f97f8ac1a313 dir: /sys/src/libc/386/sqrt.s/
TEXT sqrt(SB), $0 FMOVD a+0(FP), F0 FTST WAIT FSTSW AX SAHF JLO bad FSQRT RET bad: FMOVDP F0, F0 CALL NaN(SB) RET