newlib/libm/machine/riscv/fesetenv.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/009695399/functions/fegetenv.html
  41  * Referred to as 'fegetenv.html below.
  42  *
  43  * "The fegetenv() function shall attempt to store the current
  44  * floating-point environment in the object pointed to by envp.
  45  *
  46  * The fesetenv() function shall attempt to establish the
  47  * floating-point environment represented by the object pointed to by
  48  * envp. The argument envp shall point to an object set by a call to
  49  * fegetenv() or feholdexcept(), or equal a floating-point environment
  50  * macro. The fesetenv() function does not raise floating-point
  51  * exceptions, but only installs the state of the floating-point
  52  * status flags represented through its argument."
  53  */
  54
  55 int fesetenv(const fenv_t *envp)
  56 {
  57
  58 #ifdef __RISCV_HARD_FLOAT
  59
  60   /* Set environment (FCSR) */
  61
  62   fenv_t fcsr = *envp;
  63   asm volatile("fscsr %0" : : "r"(fcsr));
  64
  65   /* Per 'fegetenv.html:
  66    *
  67    * "If the environment was successfully established, fesetenv()
  68    * shall return zero. Otherwise, it shall return a non-zero value.
  69    */
  70
  71 #endif
  72
  73   return 0;
  74 }