arch/i387/e_exp.S

    1.1     jtc /*
    1.3     jtc  * Written by J.T. Conklin <jtc (at) netbsd.org>.
    1.3     jtc  * Public domain.
    1.1     jtc  */
    1.1     jtc
    1.1     jtc #include <machine/asm.h>
    1.1     jtc
1.8.8.1  kleink RCSID("$NetBSD: e_exp.S,v 1.8.8.1 2000/09/26 14:30:26 kleink Exp $")
    1.2     jtc
    1.1     jtc /* e^x = 2^(x * log2(e)) */
    1.1     jtc ENTRY(__ieee754_exp)
    1.6     jtc 	pushl	%ebp
    1.6     jtc 	movl	%esp,%ebp
    1.6     jtc 	subl	$8,%esp
    1.6     jtc
    1.6     jtc 	fstcw	-12(%ebp)		/* store fpu control word */
    1.6     jtc 	movw	-12(%ebp),%dx
    1.6     jtc 	orw	$0x0180,%dx
    1.6     jtc 	movw	%dx,-16(%ebp)
    1.6     jtc 	fldcw	-16(%ebp)		/* load modfied control word */
    1.6     jtc
    1.6     jtc 	fldl	8(%ebp)
    1.1     jtc 	fldl2e
    1.1     jtc 	fmulp				/* x * log2(e) */
1.8.8.1  kleink 	fldl	%st(0)
    1.1     jtc 	frndint				/* int(x * log2(e)) */
    1.7     jtc 	fxch	%st(1)
    1.7     jtc 	fsub	%st(1),%st		/* fract(x * log2(e)) */
    1.8  simonb 	f2xm1				/* 2^(fract(x * log2(e))) - 1 */
    1.1     jtc 	fld1
    1.1     jtc 	faddp				/* 2^(fract(x * log2(e))) */
    1.1     jtc 	fscale				/* e^x */
    1.5     jtc 	fstpl	%st(1)
    1.6     jtc
    1.6     jtc 	fldcw	-12(%ebp)		/* restore original control word */
    1.6     jtc
    1.6     jtc 	leave
    1.1     jtc 	ret