/*
 * Written by J.T. Conklin <jtc@netbsd.org>.
 * Public domain.
 */

#include <machine/asm.h>

RCSID("$NetBSD: e_exp.S,v 1.7 1996/07/03 17:31:28 jtc Exp $")

/* e^x = 2^(x * log2(e)) */
ENTRY(__ieee754_exp)
	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)
	fldl2e
	fmulp				/* x * log2(e) */
	fstl	%st(1)
	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 */
	fstpl	%st(1)

	fldcw	-12(%ebp)		/* restore original control word */

	leave
	ret