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fpsetmask.c revision 1.10.24.1 
      1 /*	$NetBSD: fpsetmask.c,v 1.10.24.1 2017/03/20 06:56:56 pgoyette Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1999 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Dan Winship.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 __RCSID("$NetBSD: fpsetmask.c,v 1.10.24.1 2017/03/20 06:56:56 pgoyette Exp $");
     35 #endif /* LIBC_SCCS and not lint */
     36 
     37 #include "namespace.h"
     38 
     39 #include <sys/types.h>
     40 #include <ieeefp.h>
     41 #include <powerpc/fpu.h>
     42 #include <powerpc/psl.h>
     43 
     44 #ifdef __weak_alias
     45 __weak_alias(fpsetmask,_fpsetmask)
     46 #endif
     47 
     48 #define	MASKBITS	(FPSCR_XE|FPSCR_ZE|FPSCR_UE|FPSCR_OE|FPSCR_VE)
     49 #define	MASKSHFT	3
     50 
     51 static __inline uint32_t
     52 mfmsr(void)
     53 {
     54 	uint32_t msr;
     55 
     56 	__asm volatile ("mfmsr %0" : "=r"(msr));
     57 	return msr;
     58 }
     59 
     60 static __inline void
     61 mtmsr(uint32_t msr)
     62 {
     63 
     64 	__asm volatile ("mtmsr %0" : : "r"(msr));
     65 }
     66 
     67 #include <stdio.h>
     68 
     69 fp_except
     70 fpsetmask(fp_except mask)
     71 {
     72 	union {
     73 		double u_d;
     74 		uint64_t u_fpscr;
     75 	} ud;
     76 	fp_except old, new;
     77 	uint32_t msr;
     78 
     79 	__asm volatile("mffs %0" : "=f"(ud.u_d));
     80 	old = ((uint32_t)ud.u_fpscr & MASKBITS) >> MASKSHFT;
     81 	ud.u_fpscr &= ~MASKBITS;
     82 	new = ((uint32_t)mask << MASKSHFT) & MASKBITS;
     83 	ud.u_fpscr |= new;
     84 	__asm volatile("mtfsf 0xff,%0" :: "f"(ud.u_d));
     85 
     86 	msr = mfmsr();
     87 	msr = (msr & ~(PSL_FE0 | PSL_FE1)) |
     88 		(new ? PSL_FE_PREC : PSL_FE_DIS);
     89 	mtmsr(msr);
     90 
     91 	return (old);
     92 }
     93