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142 lines
4.2 KiB
C
142 lines
4.2 KiB
C
/* Copyright (C) 1997-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _FENV_H
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# error "Never use <bits/fenv.h> directly; include <fenv.h> instead."
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#endif
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/* Define the bits representing the exception.
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Note that these are the bit positions as defined by the OSF/1
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ieee_{get,set}_control_word interface and not by the hardware fpcr.
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See the Alpha Architecture Handbook section 4.7.7.3 for details,
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but in summary, trap shadows mean the hardware register can acquire
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extra exception bits so for proper IEEE support the tracking has to
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be done in software -- in this case with kernel support.
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As to why the system call interface isn't in the same format as
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the hardware register, only those crazy folks at DEC can tell you. */
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enum
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{
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#ifdef __USE_GNU
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FE_DENORMAL =
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#define FE_DENORMAL (1 << 22)
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FE_DENORMAL,
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#endif
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FE_INEXACT =
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#define FE_INEXACT (1 << 21)
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FE_INEXACT,
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FE_UNDERFLOW =
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#define FE_UNDERFLOW (1 << 20)
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FE_UNDERFLOW,
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FE_OVERFLOW =
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#define FE_OVERFLOW (1 << 19)
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FE_OVERFLOW,
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FE_DIVBYZERO =
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#define FE_DIVBYZERO (1 << 18)
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FE_DIVBYZERO,
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FE_INVALID =
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#define FE_INVALID (1 << 17)
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FE_INVALID,
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FE_ALL_EXCEPT =
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#define FE_ALL_EXCEPT (0x3f << 17)
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FE_ALL_EXCEPT
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};
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/* Alpha chips support all four defined rouding modes.
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Note that code must be compiled to use dynamic rounding (/d) instructions
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to see these changes. For gcc this is -mfp-rounding-mode=d; for DEC cc
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this is -fprm d. The default for both is static rounding to nearest.
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These are shifted down 58 bits from the hardware fpcr because the
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functions are declared to take integers. */
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enum
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{
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FE_TOWARDZERO =
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#define FE_TOWARDZERO 0
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FE_TOWARDZERO,
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FE_DOWNWARD =
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#define FE_DOWNWARD 1
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FE_DOWNWARD,
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FE_TONEAREST =
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#define FE_TONEAREST 2
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FE_TONEAREST,
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FE_UPWARD =
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#define FE_UPWARD 3
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FE_UPWARD,
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};
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#ifdef __USE_GNU
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/* On later hardware, and later kernels for earlier hardware, we can forcibly
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underflow denormal inputs and outputs. This can speed up certain programs
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significantly, usually without affecting accuracy. */
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enum
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{
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FE_MAP_DMZ = 1UL << 12, /* Map denorm inputs to zero */
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#define FE_MAP_DMZ FE_MAP_DMZ
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FE_MAP_UMZ = 1UL << 13, /* Map underflowed outputs to zero */
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#define FE_MAP_UMZ FE_MAP_UMZ
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};
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#endif
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/* Type representing exception flags. */
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typedef unsigned long int fexcept_t;
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/* Type representing floating-point environment. */
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typedef unsigned long int fenv_t;
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/* If the default argument is used we use this value. Note that due to
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architecture-specified page mappings, no user-space pointer will ever
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have its two high bits set. Co-opt one. */
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#define FE_DFL_ENV ((const fenv_t *) 0x8800000000000000UL)
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#ifdef __USE_GNU
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/* Floating-point environment where none of the exceptions are masked. */
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# define FE_NOMASK_ENV ((const fenv_t *) 0x880000000000003eUL)
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/* Floating-point environment with (processor-dependent) non-IEEE floating
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point. In this case, mapping denormals to zero. */
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# define FE_NONIEEE_ENV ((const fenv_t *) 0x8800000000003000UL)
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#endif
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/* The system calls to talk to the kernel's FP code. */
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extern unsigned long int __ieee_get_fp_control (void) __THROW;
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extern void __ieee_set_fp_control (unsigned long int __value) __THROW;
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#if __GLIBC_USE (IEC_60559_BFP_EXT_C2X)
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/* Type representing floating-point control modes. */
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typedef unsigned long int femode_t;
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/* Default floating-point control modes. */
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# define FE_DFL_MODE ((const femode_t *) 0x8800000000000000UL)
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#endif
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