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/* Copyright (C) 1997-2024 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
<https://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 rounding 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;
#if __GLIBC_USE (IEC_60559_BFP_EXT_C2X)
/* Type representing floating-point control modes. */
typedef unsigned long int femode_t;
/* Default floating-point control modes. */
# define FE_DFL_MODE ((const femode_t *) 0x8800000000000000UL)
#endif
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