mirror of
https://github.com/KolibriOS/kolibrios.git
synced 2024-12-17 20:32:35 +03:00
50 lines
1.1 KiB
ArmAsm
50 lines
1.1 KiB
ArmAsm
/*
|
|
* Written by J.T. Conklin <jtc@netbsd.org>.
|
|
* Public domain.
|
|
*/
|
|
|
|
/* e^x = 2^(x * log2(e)) */
|
|
|
|
.file "exp.s"
|
|
.text
|
|
.p2align 4,,15
|
|
|
|
.globl _exp
|
|
.def _exp; .scl 2; .type 32; .endef
|
|
|
|
_exp:
|
|
|
|
fldl 4(%esp)
|
|
/* I added the following ugly construct because exp(+-Inf) resulted
|
|
in NaN. The ugliness results from the bright minds at Intel.
|
|
For the i686 the code can be written better.
|
|
-- drepper@cygnus.com. */
|
|
fxam /* Is NaN or +-Inf? */
|
|
fstsw %ax
|
|
movb $0x45, %dh
|
|
andb %ah, %dh
|
|
cmpb $0x05, %dh
|
|
je 1f /* Is +-Inf, jump. */
|
|
|
|
fldl2e
|
|
fmulp /* x * log2(e) */
|
|
fld %st
|
|
frndint /* int(x * log2(e)) */
|
|
fsubr %st,%st(1) /* fract(x * log2(e)) */
|
|
fxch
|
|
f2xm1 /* 2^(fract(x * log2(e))) - 1 */
|
|
fld1
|
|
faddp /* 2^(fract(x * log2(e))) */
|
|
fscale /* e^x */
|
|
fstp %st(1)
|
|
ret
|
|
|
|
1:
|
|
testl $0x200, %eax /* Test sign. */
|
|
jz 2f /* If positive, jump. */
|
|
|
|
fstp %st
|
|
fldz /* Set result to 0. */
|
|
2:
|
|
ret
|