newlib/libc/machine/shared_x86/sys/fenv.h

   1 /*
   2  * SPDX-License-Identifier: BSD-2-Clause
   3  *
   4  * Copyright (c) 2010-2019 Red Hat, Inc.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. 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  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #ifndef _SYS_FENV_H
  30 #define _SYS_FENV_H 1
  31
  32 #include <sys/cdefs.h>
  33
  34 #ifdef __cplusplus
  35 extern "C" {
  36 #endif
  37
  38
  39 /* Primary sources:
  40
  41      The Open Group Base Specifications Issue 6:
  42    http://www.opengroup.org/onlinepubs/000095399/basedefs/fenv.h.html
  43
  44      C99 Language spec (draft n1256):
  45    <url unknown>
  46
  47      Intel(R) 64 and IA-32 Architectures Software Developer's Manuals:
  48    http://www.intel.com/products/processor/manuals/
  49
  50      GNU C library manual pages:
  51    http://www.gnu.org/software/libc/manual/html_node/Control-Functions.html
  52    http://www.gnu.org/software/libc/manual/html_node/Rounding.html
  53    http://www.gnu.org/software/libc/manual/html_node/FP-Exceptions.html
  54    http://www.gnu.org/software/libc/manual/html_node/Status-bit-operations.html
  55
  56      Linux online man page(s):
  57    http://linux.die.net/man/3/fegetexcept
  58
  59     The documentation quotes these sources for reference.  All definitions and
  60    code have been developed solely based on the information from these specs.
  61
  62 */
  63
  64 /*  Represents the entire floating-point environment. The floating-point
  65    environment refers collectively to any floating-point status flags and
  66    control modes supported by the implementation.
  67     In this implementation, the struct contains the state information from
  68    the fstenv/fnstenv instructions and a copy of the SSE MXCSR, since GCC
  69    uses SSE for a lot of floating-point operations.  (Cygwin assumes i686
  70    or above these days, as does the compiler.)  */
  71
  72 typedef struct _fenv_t
  73 {
  74   struct _fpu_env_info {
  75     unsigned int _fpu_cw;       /* low 16 bits only. */
  76     unsigned int _fpu_sw;       /* low 16 bits only. */
  77     unsigned int _fpu_tagw;     /* low 16 bits only. */
  78     unsigned int _fpu_ipoff;
  79     unsigned int _fpu_ipsel;
  80     unsigned int _fpu_opoff;
  81     unsigned int _fpu_opsel;    /* low 16 bits only. */
  82   } _fpu;
  83   unsigned int _sse_mxcsr;
  84 } fenv_t;
  85
  86 /*  Represents the floating-point status flags collectively, including
  87    any status the implementation associates with the flags. A floating-point
  88    status flag is a system variable whose value is set (but never cleared)
  89    when a floating-point exception is raised, which occurs as a side effect
  90    of exceptional floating-point arithmetic to provide auxiliary information.
  91     A floating-point control mode is a system variable whose value may be
  92    set by the user to affect the subsequent behavior of floating-point
  93    arithmetic. */
  94
  95 typedef __uint32_t fexcept_t;
  96
  97 /*  The <fenv.h> header shall define the following constants if and only
  98    if the implementation supports the floating-point exception by means
  99    of the floating-point functions feclearexcept(), fegetexceptflag(),
 100    feraiseexcept(), fesetexceptflag(), and fetestexcept(). Each expands to
 101    an integer constant expression with values such that bitwise-inclusive
 102    ORs of all combinations of the constants result in distinct values.  */
 103
 104 #define FE_DIVBYZERO    (1 << 2)
 105 #define FE_INEXACT      (1 << 5)
 106 #define FE_INVALID      (1 << 0)
 107 #define FE_OVERFLOW     (1 << 3)
 108 #define FE_UNDERFLOW    (1 << 4)
 109
 110 /*  The <fenv.h> header shall define the following constant, which is
 111    simply the bitwise-inclusive OR of all floating-point exception
 112    constants defined above:  */
 113
 114 /* in agreement w/ Linux the subnormal exception will always be masked */
 115 #define FE_ALL_EXCEPT \
 116   (FE_INEXACT | FE_UNDERFLOW | FE_OVERFLOW | FE_DIVBYZERO | FE_INVALID)
 117
 118 /*  The <fenv.h> header shall define the following constants if and only
 119    if the implementation supports getting and setting the represented
 120    rounding direction by means of the fegetround() and fesetround()
 121    functions. Each expands to an integer constant expression whose values
 122    are distinct non-negative vales.  */
 123
 124 #define FE_DOWNWARD     (1)
 125 #define FE_TONEAREST    (0)
 126 #define FE_TOWARDZERO   (3)
 127 #define FE_UPWARD       (2)
 128
 129 /* Only Solaris and QNX implement fegetprec/fesetprec.  As Solaris, use the
 130    values defined by http://www.open-std.org/jtc1/sc22//WG14/www/docs/n752.htm
 131    QNX defines different values. */
 132 #if __MISC_VISIBLE
 133 #define FE_FLTPREC      (0)
 134 #define FE_DBLPREC      (2)
 135 #define FE_LDBLPREC     (3)
 136 #endif
 137
 138 /*  The <fenv.h> header shall define the following constant, which
 139    represents the default floating-point environment (that is, the one
 140    installed at program startup) and has type pointer to const-qualified
 141    fenv_t. It can be used as an argument to the functions within the
 142    <fenv.h> header that manage the floating-point environment.  */
 143
 144 extern const fenv_t *_fe_dfl_env;
 145 #define FE_DFL_ENV (_fe_dfl_env)
 146
 147 /*  Additional implementation-defined environments, with macro
 148    definitions beginning with FE_ and an uppercase letter,and having
 149    type "pointer to const-qualified fenv_t",may also be specified by
 150    the implementation.  */
 151
 152 #if __GNU_VISIBLE
 153 /*  If possible, the GNU C Library defines a macro FE_NOMASK_ENV which
 154    represents an environment where every exception raised causes a trap
 155    to occur. You can test for this macro using #ifdef. It is only defined
 156    if _GNU_SOURCE is defined.  */
 157 extern const fenv_t *_fe_nomask_env;
 158 #define FE_NOMASK_ENV (_fe_nomask_env)
 159
 160 /* These are GNU extensions defined in glibc.  */
 161 int feenableexcept (int __excepts);
 162 int fedisableexcept (int __excepts);
 163 int fegetexcept (void);
 164 #endif /* __GNU_VISIBLE */
 165
 166 #ifdef __CYGWIN__
 167
 168 #if __MISC_VISIBLE
 169 int fegetprec (void);
 170 int fesetprec (int __prec);
 171 #endif
 172
 173 #endif /* __CYGWIN__ */
 174
 175 #ifdef __cplusplus
 176 }
 177 #endif
 178
 179 #endif /* _FENV_H */