newlib/libm/machine/riscv/feupdateenv.c

   1 /*
   2   (c) Copyright 2017 Michael R. Neilly
   3   All rights reserved.
   4
   5   Redistribution and use in source and binary forms, with or without
   6   modification, are permitted provided that the following conditions
   7   are met:
   8
   9   * Redistributions of source code must retain the above copyright
  10   notice, this list of conditions and the following disclaimer.
  11
  12   * Redistributions in binary form must reproduce the above copyright
  13   notice, this list of conditions and the following disclaimer in the
  14   documentation and/or other materials provided with the distribution.
  15
  16   * Neither the names of the copyright holders nor the names of their
  17   contributors may be used to endorse or promote products derived from
  18   this software without specific prior written permission.
  19
  20   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  21   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  22   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  23   FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  24   COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  25   INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  26   BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  27   LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  28   CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29   LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  30   ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31   POSSIBILITY OF SUCH DAMAGE.
  32 */
  33
  34 #include <fenv.h>
  35 #include "riscv_math.h"
  36
  37 /* This implementation is intended to comply with the following
  38  * specification:
  39  *
  40  * http://pubs.opengroup.org/onlinepubs/9699919799/functions/feupdateenv.html
  41  *
  42  * "The feupdateenv() function shall attempt to save the currently
  43  * raised floating-point exceptions in its automatic storage, attempt
  44  * to install the floating-point environment represented by the object
  45  * pointed to by envp, and then attempt to raise the saved
  46  * floating-point exceptions. The argument envp shall point to an
  47  * object set by a call to feholdexcept() or fegetenv(), or equal a
  48  * floating-point environment macro."
  49  */
  50
  51 int feupdateenv(const fenv_t *envp)
  52 {
  53
  54 #ifdef __RISCV_HARD_FLOAT
  55
  56   /* Get current exception flags */
  57
  58   fexcept_t flags;
  59   asm volatile("frflags %0" : "=r"(flags));
  60
  61   /* Set the environment as requested */
  62
  63   fenv_t fcsr = *envp; /* Environment to install */
  64   asm volatile("fscsr %0" : : "r"(fcsr)); /* Install environment */
  65
  66   /* OR in the saved exception flags */
  67
  68   asm volatile("csrs fflags, %0" : : "r"(flags));
  69
  70   /* "The feupdateenv() function shall return a zero value if and only
  71    * if all the required actions were successfully carried out."
  72    */
  73
  74   return 0;
  75
  76 #else
  77
  78   /* For soft float */
  79
  80 #if defined FE_NOMASK_ENV && FE_ALL_EXCEPT != 0
  81
  82   if (envp == FE_NOMASK_ENV)
  83       return 1;
  84
  85 #endif
  86
  87   return 0;
  88
  89 #endif
  90 }