ref: ff03b72ed5f365a2ca052218e055fac678cf0e23 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