xref: /openbsd/lib/libm/arch/amd64/e_asin.S (revision 09467b48)
1/*	$OpenBSD: e_asin.S,v 1.5 2018/07/03 22:43:34 mortimer Exp $ */
2/*
3 * Written by J.T. Conklin <jtc@NetBSD.org>.
4 * Public domain.
5 */
6
7#include <machine/asm.h>
8
9#include "abi.h"
10
11/* asin = atan (x / sqrt(1 - x^2)) */
12ENTRY(asin)
13	RETGUARD_SETUP(asin, r11)
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	fpatan
22	XMM_DOUBLE_EPILOGUE
23	RETGUARD_CHECK(asin, r11)
24	ret
25END_STD(asin)
26