lib/libc/arch/powerpc/gen/fpsetsticky.c

   1 /*      $NetBSD: fpsetsticky.c,v 1.11 2011/07/10 21:18:47 matt 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: fpsetsticky.c,v 1.11 2011/07/10 21:18:47 matt 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
  43 #define STICKYBITS      (FPSCR_XX|FPSCR_ZX|FPSCR_UX|FPSCR_OX|FPSCR_VX)
  44 #define INVBITS         (FPSCR_VXCVI|FPSCR_VXSQRT|FPSCR_VXSOFT|FPSCR_VXVC|\
  45                          FPSCR_VXIMZ|FPSCR_VXZDZ|FPSCR_VXIDI|FPSCR_VXISI|\
  46                          FPSCR_VXSNAN)
  47 #define STICKYSHFT      25
  48
  49 #ifdef __weak_alias
  50 __weak_alias(fpsetsticky,_fpsetsticky)
  51 #endif
  52
  53 fp_except
  54 fpsetsticky(fp_except mask)
  55 {
  56         union {
  57                 double u_d;
  58                 uint64_t u_fpscr;
  59         } ud;
  60         fp_except old;
  61
  62         __asm volatile("mffs %0" : "=f"(ud.u_d));
  63         old = ((uint32_t)ud.u_fpscr & STICKYBITS) >> STICKYSHFT;
  64         /*
  65          * FPSCR_VX (aka FP_X_INV) is not a sticky bit but a summary of the
  66          * all the FPSCR_VX* sticky bits.  So when FP_X_INV is cleared then
  67          * clear all of those bits, likewise when it's set, set them all.
  68          */
  69         if ((mask & FP_X_INV) == 0)
  70                 ud.u_fpscr &= ~INVBITS;
  71         else
  72                 ud.u_fpscr |= INVBITS;
  73         ud.u_fpscr &= ~STICKYBITS;
  74         ud.u_fpscr |= ((uint32_t)mask << STICKYSHFT) & STICKYBITS;
  75         /*
  76          * Make FPSCR_FX reflect the presence of a set sticky bit (or not).
  77          */
  78         if (ud.u_fpscr & (STICKYBITS|INVBITS))
  79                 ud.u_fpscr |= FPSCR_FX;
  80         else
  81                 ud.u_fpscr &= ~FPSCR_FX;
  82         /*
  83          * Write back the fpscr.
  84          */
  85         __asm volatile("mtfsf 0xff,%0" :: "f"(ud.u_d));
  86         return (old);
  87 }