NetBSD/lib/libm/arch/i387/e_exp.S

56 lines
1010 B
ArmAsm

/*
* Written by J.T. Conklin <jtc@netbsd.org>.
* Public domain.
*/
#include <machine/asm.h>
#include "abi.h"
RCSID("$NetBSD: e_exp.S,v 1.11 2001/06/19 17:49:36 fvdl Exp $")
/* e^x = 2^(x * log2(e)) */
ENTRY(__ieee754_exp)
#ifdef __i386__
pushl %ebp
movl %esp,%ebp
subl $8,%esp
fstcw -12(%ebp) /* store fpu control word */
movw -12(%ebp),%dx
orw $0x0180,%dx
movw %dx,-16(%ebp)
fldcw -16(%ebp) /* load modfied control word */
fldl 8(%ebp)
#else
fstcw -12(%rsp)
movw -12(%rsp),%dx
orw $0x0180,%dx
movw %dx,-16(%rsp)
fldcw -16(%rsp)
movsd %xmm0,-8(%rsp)
fldl -8(%rsp)
#endif
fldl2e
fmulp /* x * log2(e) */
fld %st(0)
frndint /* int(x * log2(e)) */
fxch %st(1)
fsub %st(1),%st /* fract(x * log2(e)) */
f2xm1 /* 2^(fract(x * log2(e))) - 1 */
fld1
faddp /* 2^(fract(x * log2(e))) */
fscale /* e^x */
fstp %st(1)
#ifdef __i386__
fldcw -12(%ebp) /* restore original control word */
leave
#else
fstpl -8(%rsp)
movsd -8(%rsp),%xmm0
fldcw -12(%rsp)
#endif
ret