1 /**
2 * This file has no copyright assigned and is placed in the Public Domain.
3 * This file is part of the mingw-w64 runtime package.
4 * No warranty is given; refer to the file DISCLAIMER.PD within this package.
5 */
6 /*
7 * Written by J.T. Conklin <jtc@netbsd.org>.
8 * Public domain.
9 */
10
11 #include <math.h>
12
13 float
acosf(float x)14 acosf (float x)
15 {
16 float res = 0.0F;
17
18 /* acosl = atanl (sqrtl(1 - x^2) / x) */
19 asm volatile (
20 "fld %%st\n\t"
21 "fmul %%st(0)\n\t" /* x^2 */
22 "fld1\n\t"
23 "fsubp\n\t" /* 1 - x^2 */
24 "fsqrt\n\t" /* sqrtl (1 - x^2) */
25 "fxch %%st(1)\n\t"
26 "fpatan"
27 : "=t" (res) : "0" (x) : "st(1)");
28 return res;
29 }
30