/* * 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(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