Alpha specific FP environment definitions.
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/* Copyright (C) 1997 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Richard Henderson <rth@tamu.edu>, 1997
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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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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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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FE_INEXACT = 1UL << 21,
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#define FE_INEXACT FE_INEXACT
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FE_UNDERFLOW = 1UL << 20,
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#define FE_UNDERFLOW FE_UNDERFLOW
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FE_OVERFLOW = 1UL << 19,
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#define FE_OVERFLOW FE_OVERFLOW
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FE_DIVBYZERO = 1UL << 18,
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#define FE_DIVBYZERO FE_DIVBYZERO
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FE_INVALID = 1UL << 17,
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#define FE_INVALID FE_INVALID
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FE_ALL_EXCEPT =
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(FE_INEXACT | FE_DIVBYZERO | FE_UNDERFLOW | FE_OVERFLOW | FE_INVALID)
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#define FE_ALL_EXCEPT 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_TOWARDSZERO = 0,
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#define FE_TOWARDSZERO FE_TOWARDSZERO
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FE_DOWNWARD = 1,
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#define FE_DOWNWARD FE_DOWNWARD
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FE_TONEAREST = 2,
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#define FE_TONEAREST FE_TONEAREST
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FE_UPWARD = 3,
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#define FE_UPWARD FE_UPWARD
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};
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/* Type representing exception flags. */
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typedef unsigned long fexcept_t;
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/* Type representing floating-point environment. */
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typedef unsigned long 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 ((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 ((fenv_t *) 0x880000000000003eUL)
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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 __ieee_get_fp_control(void);
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extern void __ieee_set_fp_control(unsigned long);
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