forked from KolibriOS/kolibrios
49 lines
1.1 KiB
ArmAsm
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 "log10.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 _log10
|
|
.def _log10; .scl 2; .type 32; .endef
|
|
_log10:
|
|
fldlg2 /* log10(2) */
|
|
fldl 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
|