xref: /minix3/lib/libm/arch/i387/e_acos.S (revision 0a6a1f1d05b60e214de2f05a7310ddd1f0e590e7)
1/*
2 * Written by J.T. Conklin <jtc@NetBSD.org>.
3 * Public domain.
4 */
5
6#include <machine/asm.h>
7
8#include "abi.h"
9
10RCSID("$NetBSD: e_acos.S,v 1.9 2014/03/03 08:00:50 dsl Exp $")
11
12/* acos = atan (sqrt(1 - x^2) / x) */
13ENTRY(__ieee754_acos)
14	XMM_ONE_ARG_DOUBLE_PROLOGUE
15	fldl	ARG_DOUBLE_ONE		/* x */
16	fld	%st(0)
17	fmul	%st(0)			/* x^2 */
18	fld1
19	fsubp				/* 1 - x^2 */
20	fsqrt				/* sqrt (1 - x^2) */
21	fabs				/* Change -0.0 to +0.0 */
22	fxch	%st(1)
23	fpatan
24	XMM_DOUBLE_EPILOGUE
25	ret
26