e_sqrtf.c revision 1.3 
1/*	$OpenBSD: e_sqrtf.c,v 1.3 2016/09/12 19:47:02 guenther Exp $	*/
2
3/*
4 * Written by Martynas Venckus.  Public domain
5 */
6
7#include <sys/types.h>
8#include <math.h>
9
10#define	FPSCR_PR	(1 << 19)
11
12float
13sqrtf(float f)
14{
15	register_t fpscr, nfpscr;
16
17	__asm__ volatile ("sts fpscr, %0" : "=r" (fpscr));
18
19	/* Set floating-point mode to single-precision. */
20	nfpscr = fpscr & ~FPSCR_PR;
21
22	__asm__ volatile ("lds %0, fpscr" : : "r" (nfpscr));
23	__asm__ volatile ("fsqrt %0" : "+f" (f));
24
25	/* Restore fp status/control register. */
26	__asm__ volatile ("lds %0, fpscr" : : "r" (fpscr));
27
28	return (f);
29}
30DEF_STD(sqrtf);
31