glibc/sysdeps/i386/fpu/e_log10l.S
Ulrich Drepper 0ac5ae2335 Optimize libm
libm is now somewhat integrated with gcc's -ffinite-math-only option
and lots of the wrapper functions have been optimized.
2011-10-12 11:27:51 -04:00

68 lines
1.4 KiB
ArmAsm

/*
* Written by J.T. Conklin <jtc@netbsd.org>.
* Public domain.
*
* Adapted for `long double' by Ulrich Drepper <drepper@cygnus.com>.
*
* Changed to use fyl2xp1 for values near 1, <drepper@cygnus.com>.
*/
#include <machine/asm.h>
#ifdef __ELF__
.section .rodata.cst8,"aM",@progbits,8
#else
.text
#endif
.p2align 3
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_log10l)
fldlg2 // log10(2)
fldt 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_log10l)
strong_alias (__ieee754_log10l, __log10l_finite)