lib/libc/arch/arm/hardfloat/fpsetround.c

   1 /*      $NetBSD: fpsetround.c,v 1.8 2013/02/03 01:50:54 matt Exp $      */
   2
   3 /*-
   4  * Copyright (c) 2013 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Matt Thomas of 3am Software Foundry.
   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 #ifndef __VFP_FP__
  33 #error FPA is not supported anymore
  34 #endif
  35
  36 #include <sys/cdefs.h>
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 __RCSID("$NetBSD: fpsetround.c,v 1.8 2013/02/03 01:50:54 matt Exp $");
  39 #endif /* LIBC_SCCS and not lint */
  40
  41 #include "namespace.h"
  42
  43 #include <sys/types.h>
  44 #include <ieeefp.h>
  45
  46 #include <arm/vfpreg.h>
  47
  48 #ifdef __weak_alias
  49 __weak_alias(fpsetround,_fpsetround)
  50 #endif
  51
  52 /*
  53  * Return the current FP rounding mode
  54  */
  55
  56 fp_rnd
  57 fpsetround(fp_rnd new_rnd)
  58 {
  59         __CTASSERT(__SHIFTOUT(VFP_FPSCR_RN, VFP_FPSCR_RMODE) == FP_RN);
  60         __CTASSERT(__SHIFTOUT(VFP_FPSCR_RP, VFP_FPSCR_RMODE) == FP_RP);
  61         __CTASSERT(__SHIFTOUT(VFP_FPSCR_RM, VFP_FPSCR_RMODE) == FP_RM);
  62         __CTASSERT(__SHIFTOUT(VFP_FPSCR_RZ, VFP_FPSCR_RMODE) == FP_RZ);
  63         uint32_t fpscr;
  64         __asm __volatile("vmrs %0, fpscr" : "=r" (fpscr));
  65         fp_rnd old_rnd = __SHIFTOUT(fpscr, VFP_FPSCR_RMODE);
  66         fpscr ^= __SHIFTIN(new_rnd ^ old_rnd, VFP_FPSCR_RMODE);
  67         __asm __volatile("vmsr fpscr, %0" :: "r" (fpscr));
  68         return old_rnd;
  69 }