1/*	$OpenBSD: s_trunc.c,v 1.9 2023/01/27 16:43:33 miod Exp $	*/
2/*
3 * Written by Michael Shalayeff. Public Domain
4 */
5
6#include <sys/types.h>
7#include <machine/ieeefp.h>
8#include "math.h"
9
10double
11trunc(double x)
12{
13	u_int64_t ofpsr, fpsr;
14
15	__asm__ volatile("fstds %%fr0,0(%1)" : "=m" (ofpsr) : "r" (&ofpsr));
16	fpsr = (ofpsr & ~((u_int64_t)FP_RM << (9 + 32))) |
17	    ((u_int64_t)FP_RZ << (9 + 32));
18	__asm__ volatile("fldds 0(%0), %%fr0" :: "r" (&fpsr), "m" (fpsr));
19
20	__asm__ volatile("frnd,dbl %0,%0" : "+f" (x));
21
22	__asm__ volatile("fldds 0(%0), %%fr0" :: "r" (&ofpsr), "m" (ofpsr));
23	return (x);
24}
25DEF_STD(trunc);
26LDBL_UNUSED_CLONE(trunc);
27