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/*
* Written by J.T. Conklin <jtc@netbsd.org>.
* Public domain.
* Adapted for float type by Ulrich Drepper <drepper@cygnus.com>.
*
* Changed to use fyl2xp1 for values near 1, <drepper@cygnus.com>.
*/
#include <machine/asm.h>
RCSID("$NetBSD: $")
#ifdef __ELF__
.section .rodata
#else
.text
#endif
.align ALIGNARG(4)
ASM_TYPE_DIRECTIVE(one,@object)
one: .double 1.0
ASM_SIZE_DIRECTIVE(one)
/* 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. */
ASM_TYPE_DIRECTIVE(limit,@object)
limit: .double 0.29
ASM_SIZE_DIRECTIVE(limit)
#ifdef PIC
#define MO(op) op##@GOTOFF(%edx)
#else
#define MO(op) op
#endif
.text
ENTRY(__ieee754_log10f)
fldlg2 // log10(2)
flds 4(%esp) // x : log10(2)
#ifdef PIC
LOAD_PIC_REG (dx)
#endif
fxam
fnstsw
fld %st // x : x : log10(2)
sahf
jc 3f // in case x is NaN or ±Inf
4: fsubl MO(one) // x-1 : x : log10(2)
fld %st // x-1 : x-1 : x : log10(2)
fabs // |x-1| : x-1 : x : log10(2)
fcompl MO(limit) // x-1 : x : log10(2)
fnstsw // x-1 : x : log10(2)
andb $0x45, %ah
jz 2f
fstp %st(1) // x-1 : log10(2)
fyl2xp1 // log10(x)
ret
2: fstp %st(0) // x : log10(2)
fyl2x // log10(x)
ret
3: jp 4b // in case x is ±Inf
fstp %st(1)
fstp %st(1)
ret
END (__ieee754_log10f)
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