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fpsetsticky.c revision 1.1 
      1 /*	$NetBSD: fpsetsticky.c,v 1.1 2006/07/01 16:37:20 ross 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  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the NetBSD
     21  *	Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 #if defined(LIBC_SCCS) && !defined(lint)
     41 __RCSID("$NetBSD: fpsetsticky.c,v 1.1 2006/07/01 16:37:20 ross Exp $");
     42 #endif /* LIBC_SCCS and not lint */
     43 
     44 #include "namespace.h"
     45 
     46 #include <sys/types.h>
     47 #include <ieeefp.h>
     48 #include <powerpc/fpu.h>
     49 
     50 #define	STICKYBITS	(FPSCR_XX|FPSCR_ZX|FPSCR_UX|FPSCR_OX|FPSCR_VX)
     51 #define	INVBITS		(FPSCR_VXCVI|FPSCR_VXSQRT|FPSCR_VXSOFT|FPSCR_VXVC|\
     52 			 FPSCR_VXIMZ|FPSCR_VXZDZ|FPSCR_VXIDI|FPSCR_VXISI|\
     53 			 FPSCR_VXSNAN)
     54 #define	STICKYSHFT	25
     55 
     56 #ifdef __weak_alias
     57 __weak_alias(fpsetsticky,_fpsetsticky)
     58 #endif
     59 
     60 fp_except
     61 fpsetsticky(fp_except mask)
     62 {
     63 	uint64_t fpscr;
     64 	fp_except old;
     65 
     66 	__asm volatile("mffs %0" : "=f"(fpscr));
     67 	old = ((uint32_t)fpscr & STICKYBITS) >> STICKYSHFT;
     68 	/*
     69 	 * FPSCR_VX (aka FP_X_INV) is not a sticky bit but a summary of the
     70 	 * all the FPSCR_VX* sticky bits.  So when FP_X_INV is cleared then
     71 	 * clear all of those bits, likewise when it's set, set them all.
     72 	 */
     73 	if ((mask & FP_X_INV) == 0)
     74 		fpscr &= ~INVBITS;
     75 	else
     76 		fpscr |= INVBITS;
     77 	fpscr &= ~STICKYBITS;
     78 	fpscr |= ((uint32_t)mask << STICKYSHFT) & STICKYBITS;
     79 	/*
     80 	 * Make FPSCR_FX reflect the presence of a set sticky bit (or not).
     81 	 */
     82 	if (fpscr & (STICKYBITS|INVBITS))
     83 		fpscr |= FPSCR_FX;
     84 	else
     85 		fpscr &= ~FPSCR_FX;
     86 	/*
     87 	 * Write back the fpscr.
     88 	 */
     89 	__asm volatile("mtfsf 0xff,%0" :: "f"(fpscr));
     90 	return (old);
     91 }
     92