text: /* Copyright (C) 1997-2016 Free Software Foundation, Inc.
     This file is part of the GNU C Library.
  
     The GNU C Library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 of the License, or (at your option) any later version.
  
     The GNU C Library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public
     License along with the GNU C Library.  If not, see
     <http://www.gnu.org/licenses/>.  */
  
  #ifndef _FENV_H
  # error "Never use <bits/fenv.h> directly; include <fenv.h> instead."
  #endif
  
  
  /* Define the bits representing the exception.
  
     Note that these are the bit positions as defined by the OSF/1
     ieee_{get,set}_control_word interface and not by the hardware fpcr.
  
     See the Alpha Architecture Handbook section 4.7.7.3 for details,
     but in summary, trap shadows mean the hardware register can acquire
     extra exception bits so for proper IEEE support the tracking has to
     be done in software -- in this case with kernel support.
  
     As to why the system call interface isn't in the same format as
     the hardware register, only those crazy folks at DEC can tell you.  */
  
  enum
    {
  #ifdef __USE_GNU
      FE_DENORMAL =
  #define FE_DENORMAL	(1 << 22)
        FE_DENORMAL,
  #endif
  
      FE_INEXACT =
  #define FE_INEXACT	(1 << 21)
        FE_INEXACT,
  
      FE_UNDERFLOW =
  #define FE_UNDERFLOW	(1 << 20)
        FE_UNDERFLOW,
  
      FE_OVERFLOW =
  #define FE_OVERFLOW	(1 << 19)
        FE_OVERFLOW,
  
      FE_DIVBYZERO =
  #define FE_DIVBYZERO	(1 << 18)
        FE_DIVBYZERO,
  
      FE_INVALID =
  #define FE_INVALID	(1 << 17)
        FE_INVALID,
  
      FE_ALL_EXCEPT =
  #define FE_ALL_EXCEPT	(0x3f << 17)
        FE_ALL_EXCEPT
    };
  
  /* Alpha chips support all four defined rouding modes.
  
     Note that code must be compiled to use dynamic rounding (/d) instructions
     to see these changes.  For gcc this is -mfp-rounding-mode=d; for DEC cc
     this is -fprm d.  The default for both is static rounding to nearest.
  
     These are shifted down 58 bits from the hardware fpcr because the
     functions are declared to take integers.  */
  
  enum
    {
      FE_TOWARDZERO =
  #define FE_TOWARDZERO	0
        FE_TOWARDZERO,
  
      FE_DOWNWARD =
  #define FE_DOWNWARD	1
        FE_DOWNWARD,
  
      FE_TONEAREST =
  #define FE_TONEAREST	2
        FE_TONEAREST,
  
      FE_UPWARD =
  #define FE_UPWARD	3
        FE_UPWARD,
    };
  
  #ifdef __USE_GNU
  /* On later hardware, and later kernels for earlier hardware, we can forcibly
     underflow denormal inputs and outputs.  This can speed up certain programs
     significantly, usually without affecting accuracy.  */
  enum
    {
      FE_MAP_DMZ =	1UL << 12,	/* Map denorm inputs to zero */
  #define FE_MAP_DMZ	FE_MAP_DMZ
  
      FE_MAP_UMZ =	1UL << 13,	/* Map underflowed outputs to zero */
  #define FE_MAP_UMZ	FE_MAP_UMZ
    };
  #endif
  
  /* Type representing exception flags.  */
  typedef unsigned long int fexcept_t;
  
  /* Type representing floating-point environment.  */
  typedef unsigned long int fenv_t;
  
  /* If the default argument is used we use this value.  Note that due to
     architecture-specified page mappings, no user-space pointer will ever
     have its two high bits set.  Co-opt one.  */
  #define FE_DFL_ENV	((const fenv_t *) 0x8800000000000000UL)
  
  #ifdef __USE_GNU
  /* Floating-point environment where none of the exceptions are masked.  */
  # define FE_NOMASK_ENV	((const fenv_t *) 0x880000000000003eUL)
  
  /* Floating-point environment with (processor-dependent) non-IEEE floating
     point.  In this case, mapping denormals to zero.  */
  # define FE_NONIEEE_ENV ((const fenv_t *) 0x8800000000003000UL)
  #endif
  
  /* The system calls to talk to the kernel's FP code.  */
  extern unsigned long int __ieee_get_fp_control (void) __THROW;
  extern void __ieee_set_fp_control (unsigned long int __value) __THROW;
  