/* * Written by J.T. Conklin . * Public domain. * Adapted for float by Ulrich Drepper . * * Changed to use fyl2xp1 for values near 1, . */ .file "logf.S" .text .align 4 one: .double 1.0 /* It is not important that this constant is precise. It is only a value which is known to be on the safe side for using the fyl2xp1 instruction. */ limit: .double 0.29 .text .align 4 .globl _logf .def _logf; .scl 2; .type 32; .endef _logf: fldln2 // log(2) flds 4(%esp) // x : log(2) fld %st // x : x : log(2) fsubl one // x-1 : x : log(2) fld %st // x-1 : x-1 : x : log(2) fabs // |x-1| : x-1 : x : log(2) fcompl limit // x-1 : x : log(2) fnstsw // x-1 : x : log(2) andb $0x45, %ah jz 2f fstp %st(1) // x-1 : log(2) fyl2xp1 // log(x) ret 2: fstp %st(0) // x : log(2) fyl2x // log(x) ret