kolibrios/programs/develop/libraries/newlib/math/log10f.S
Sergey Semyonov (Serge) 2336060a0c newlib: update
git-svn-id: svn://kolibrios.org@1906 a494cfbc-eb01-0410-851d-a64ba20cac60
2011-03-11 18:52:24 +00:00

49 lines
1.1 KiB
ArmAsm

/*
* 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>.
*/
.file "log10f.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 _log10f
.def _log10f; .scl 2; .type 32; .endef
_log10f:
fldlg2 /* log10(2) */
flds 4(%esp) /* x : log10(2) */
fxam
fnstsw
fld %st /* x : x : log10(2) */
sahf
jc 3f /* in case x is NaN or ±Inf */
4: fsubl one /* x-1 : x : log10(2) */
fld %st /* x-1 : x-1 : x : log10(2) */
fabs /* |x-1| : x-1 : x : log10(2) */
fcompl 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