xref: /netbsd-src/lib/libc/arch/sparc64/gen/fpsetround.c (revision aabd8f68bab7dab89a501bb74b70467440f5c523)
1 /*	$NetBSD: fpsetround.c,v 1.9 2024/03/20 06:15:39 rillig Exp $	*/
2 
3 /*
4  * Written by J.T. Conklin, Apr 10, 1995
5  * Public domain.
6  */
7 
8 #include <sys/cdefs.h>
9 #if defined(LIBC_SCCS) && !defined(lint)
10 __RCSID("$NetBSD: fpsetround.c,v 1.9 2024/03/20 06:15:39 rillig Exp $");
11 #endif /* LIBC_SCCS and not lint */
12 
13 #include "namespace.h"
14 
15 #include <sys/types.h>
16 #include <ieeefp.h>
17 
18 #ifdef __weak_alias
19 __weak_alias(fpsetround,_fpsetround)
20 #endif
21 
22 #ifdef SOFTFLOATSPARC64_FOR_GCC
23 extern fp_rnd _softfloat_float_rounding_mode;
24 #endif
25 
26 fp_rnd
fpsetround(fp_rnd rnd_dir)27 fpsetround(fp_rnd rnd_dir)
28 {
29 	fp_rnd old;
30 	fp_rnd new;
31 
32 	__asm("st %%fsr,%0" : "=m" (*&old));
33 
34 #ifdef SOFTFLOATSPARC64_FOR_GCC
35 	_softfloat_float_rounding_mode = rnd_dir;
36 #endif
37 
38 	new = old;
39 	new &= ~(0x03U << 30);
40 	new |= ((rnd_dir & 0x03U) << 30);
41 
42 	__asm("ld %0,%%fsr" : : "m" (*&new));
43 
44 	return ((uint32_t)old >> 30) & 0x03;
45 }
46