soft-fp/soft-fp.h

   1 /* Software floating-point emulation.
   2    Copyright (C) 1997-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    In addition to the permissions in the GNU Lesser General Public
  11    License, the Free Software Foundation gives you unlimited
  12    permission to link the compiled version of this file into
  13    combinations with other programs, and to distribute those
  14    combinations without any restriction coming from the use of this
  15    file.  (The Lesser General Public License restrictions do apply in
  16    other respects; for example, they cover modification of the file,
  17    and distribution when not linked into a combine executable.)
  18
  19    The GNU C Library is distributed in the hope that it will be useful,
  20    but WITHOUT ANY WARRANTY; without even the implied warranty of
  21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  22    Lesser General Public License for more details.
  23
  24    You should have received a copy of the GNU Lesser General Public
  25    License along with the GNU C Library; if not, see
  26    <https://www.gnu.org/licenses/>.  */
  27
  28 #ifndef SOFT_FP_H
  29 #define SOFT_FP_H       1
  30
  31 #ifdef _LIBC
  32 # include <sfp-machine.h>
  33 #elif defined __KERNEL__
  34 /* The Linux kernel uses asm/ names for architecture-specific
  35    files.  */
  36 # include <asm/sfp-machine.h>
  37 #else
  38 # include "sfp-machine.h"
  39 #endif
  40
  41 /* Allow sfp-machine to have its own byte order definitions.  */
  42 #ifndef __BYTE_ORDER
  43 # ifdef _LIBC
  44 #  include <endian.h>
  45 # else
  46 #  error "endianness not defined by sfp-machine.h"
  47 # endif
  48 #endif
  49
  50 /* For unreachable default cases in switch statements over bitwise OR
  51    of FP_CLS_* values.  */
  52 #if (defined __GNUC__                                                   \
  53      && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)))
  54 # define _FP_UNREACHABLE        __builtin_unreachable ()
  55 #else
  56 # define _FP_UNREACHABLE        abort ()
  57 #endif
  58
  59 #if ((defined __GNUC__                                                  \
  60       && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)))      \
  61      || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 201112L))
  62 # define _FP_STATIC_ASSERT(expr, msg)           \
  63   _Static_assert ((expr), msg)
  64 #else
  65 # define _FP_STATIC_ASSERT(expr, msg)                                   \
  66   extern int (*__Static_assert_function (void))                         \
  67     [!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
  68 #endif
  69
  70 /* In the Linux kernel, some architectures have a single function that
  71    uses different kinds of unpacking and packing depending on the
  72    instruction being emulated, meaning it is not readily visible to
  73    the compiler that variables from _FP_DECL and _FP_FRAC_DECL_*
  74    macros are only used in cases where they were initialized.  */
  75 #ifdef __KERNEL__
  76 # define _FP_ZERO_INIT          = 0
  77 #else
  78 # define _FP_ZERO_INIT
  79 #endif
  80
  81 #define _FP_WORKBITS            3
  82 #define _FP_WORK_LSB            ((_FP_W_TYPE) 1 << 3)
  83 #define _FP_WORK_ROUND          ((_FP_W_TYPE) 1 << 2)
  84 #define _FP_WORK_GUARD          ((_FP_W_TYPE) 1 << 1)
  85 #define _FP_WORK_STICKY         ((_FP_W_TYPE) 1 << 0)
  86
  87 #ifndef FP_RND_NEAREST
  88 # define FP_RND_NEAREST         0
  89 # define FP_RND_ZERO            1
  90 # define FP_RND_PINF            2
  91 # define FP_RND_MINF            3
  92 #endif
  93 #ifndef FP_ROUNDMODE
  94 # define FP_ROUNDMODE           FP_RND_NEAREST
  95 #endif
  96
  97 /* By default don't care about exceptions.  */
  98 #ifndef FP_EX_INVALID
  99 # define FP_EX_INVALID          0
 100 #endif
 101 #ifndef FP_EX_OVERFLOW
 102 # define FP_EX_OVERFLOW         0
 103 #endif
 104 #ifndef FP_EX_UNDERFLOW
 105 # define FP_EX_UNDERFLOW        0
 106 #endif
 107 #ifndef FP_EX_DIVZERO
 108 # define FP_EX_DIVZERO          0
 109 #endif
 110 #ifndef FP_EX_INEXACT
 111 # define FP_EX_INEXACT          0
 112 #endif
 113 #ifndef FP_EX_DENORM
 114 # define FP_EX_DENORM           0
 115 #endif
 116
 117 /* Sub-exceptions of "invalid".  */
 118 /* Signaling NaN operand.  */
 119 #ifndef FP_EX_INVALID_SNAN
 120 # define FP_EX_INVALID_SNAN     0
 121 #endif
 122 /* Inf * 0.  */
 123 #ifndef FP_EX_INVALID_IMZ
 124 # define FP_EX_INVALID_IMZ      0
 125 #endif
 126 /* fma (Inf, 0, c).  */
 127 #ifndef FP_EX_INVALID_IMZ_FMA
 128 # define FP_EX_INVALID_IMZ_FMA  0
 129 #endif
 130 /* Inf - Inf.  */
 131 #ifndef FP_EX_INVALID_ISI
 132 # define FP_EX_INVALID_ISI      0
 133 #endif
 134 /* 0 / 0.  */
 135 #ifndef FP_EX_INVALID_ZDZ
 136 # define FP_EX_INVALID_ZDZ      0
 137 #endif
 138 /* Inf / Inf.  */
 139 #ifndef FP_EX_INVALID_IDI
 140 # define FP_EX_INVALID_IDI      0
 141 #endif
 142 /* sqrt (negative).  */
 143 #ifndef FP_EX_INVALID_SQRT
 144 # define FP_EX_INVALID_SQRT     0
 145 #endif
 146 /* Invalid conversion to integer.  */
 147 #ifndef FP_EX_INVALID_CVI
 148 # define FP_EX_INVALID_CVI      0
 149 #endif
 150 /* Invalid comparison.  */
 151 #ifndef FP_EX_INVALID_VC
 152 # define FP_EX_INVALID_VC       0
 153 #endif
 154
 155 /* _FP_STRUCT_LAYOUT may be defined as an attribute to determine the
 156    struct layout variant used for structures where bit-fields are used
 157    to access specific parts of binary floating-point numbers.  This is
 158    required for systems where the default ABI uses struct layout with
 159    differences in how consecutive bit-fields are laid out from the
 160    default expected by soft-fp.  */
 161 #ifndef _FP_STRUCT_LAYOUT
 162 # define _FP_STRUCT_LAYOUT
 163 #endif
 164
 165 #ifdef _FP_DECL_EX
 166 # define FP_DECL_EX                                     \
 167   int _fex = 0;                                         \
 168   _FP_DECL_EX
 169 #else
 170 # define FP_DECL_EX int _fex = 0
 171 #endif
 172
 173 /* Initialize any machine-specific state used in FP_ROUNDMODE,
 174    FP_TRAPPING_EXCEPTIONS or FP_HANDLE_EXCEPTIONS.  */
 175 #ifndef FP_INIT_ROUNDMODE
 176 # define FP_INIT_ROUNDMODE do {} while (0)
 177 #endif
 178
 179 /* Initialize any machine-specific state used in
 180    FP_TRAPPING_EXCEPTIONS or FP_HANDLE_EXCEPTIONS.  */
 181 #ifndef FP_INIT_TRAPPING_EXCEPTIONS
 182 # define FP_INIT_TRAPPING_EXCEPTIONS FP_INIT_ROUNDMODE
 183 #endif
 184
 185 /* Initialize any machine-specific state used in
 186    FP_HANDLE_EXCEPTIONS.  */
 187 #ifndef FP_INIT_EXCEPTIONS
 188 # define FP_INIT_EXCEPTIONS FP_INIT_TRAPPING_EXCEPTIONS
 189 #endif
 190
 191 #ifndef FP_HANDLE_EXCEPTIONS
 192 # define FP_HANDLE_EXCEPTIONS do {} while (0)
 193 #endif
 194
 195 /* Whether to flush subnormal inputs to zero with the same sign.  */
 196 #ifndef FP_DENORM_ZERO
 197 # define FP_DENORM_ZERO 0
 198 #endif
 199
 200 #ifndef FP_INHIBIT_RESULTS
 201 /* By default we write the results always.
 202    sfp-machine may override this and e.g.
 203    check if some exceptions are unmasked
 204    and inhibit it in such a case.  */
 205 # define FP_INHIBIT_RESULTS 0
 206 #endif
 207
 208 #define FP_SET_EXCEPTION(ex)                            \
 209   _fex |= (ex)
 210
 211 #define FP_CUR_EXCEPTIONS                               \
 212   (_fex)
 213
 214 #ifndef FP_TRAPPING_EXCEPTIONS
 215 # define FP_TRAPPING_EXCEPTIONS 0
 216 #endif
 217
 218 /* A file using soft-fp may define FP_NO_EXCEPTIONS before including
 219    soft-fp.h to indicate that, although a macro used there could raise
 220    exceptions, or do rounding and potentially thereby raise
 221    exceptions, for some arguments, for the particular arguments used
 222    in that file no exceptions or rounding can occur.  Such a file
 223    should not itself use macros relating to handling exceptions and
 224    rounding modes; this is only for indirect uses (in particular, in
 225    _FP_FROM_INT and the macros it calls).  */
 226 #ifdef FP_NO_EXCEPTIONS
 227
 228 # undef FP_SET_EXCEPTION
 229 # define FP_SET_EXCEPTION(ex) do {} while (0)
 230
 231 # undef FP_CUR_EXCEPTIONS
 232 # define FP_CUR_EXCEPTIONS 0
 233
 234 # undef FP_TRAPPING_EXCEPTIONS
 235 # define FP_TRAPPING_EXCEPTIONS 0
 236
 237 # undef FP_ROUNDMODE
 238 # define FP_ROUNDMODE FP_RND_ZERO
 239
 240 # undef _FP_TININESS_AFTER_ROUNDING
 241 # define _FP_TININESS_AFTER_ROUNDING 0
 242
 243 #endif
 244
 245 /* A file using soft-fp may define FP_NO_EXACT_UNDERFLOW before
 246    including soft-fp.h to indicate that, although a macro used there
 247    could allow for the case of exact underflow requiring the underflow
 248    exception to be raised if traps are enabled, for the particular
 249    arguments used in that file no exact underflow can occur.  */
 250 #ifdef FP_NO_EXACT_UNDERFLOW
 251 # undef FP_TRAPPING_EXCEPTIONS
 252 # define FP_TRAPPING_EXCEPTIONS 0
 253 #endif
 254
 255 #define _FP_ROUND_NEAREST(wc, X)                                \
 256   do                                                            \
 257     {                                                           \
 258       if ((_FP_FRAC_LOW_##wc (X) & 15) != _FP_WORK_ROUND)       \
 259         _FP_FRAC_ADDI_##wc (X, _FP_WORK_ROUND);                 \
 260     }                                                           \
 261   while (0)
 262
 263 #define _FP_ROUND_ZERO(wc, X)           (void) 0
 264
 265 #define _FP_ROUND_PINF(wc, X)                           \
 266   do                                                    \
 267     {                                                   \
 268       if (!X##_s && (_FP_FRAC_LOW_##wc (X) & 7))        \
 269         _FP_FRAC_ADDI_##wc (X, _FP_WORK_LSB);           \
 270     }                                                   \
 271   while (0)
 272
 273 #define _FP_ROUND_MINF(wc, X)                   \
 274   do                                            \
 275     {                                           \
 276       if (X##_s && (_FP_FRAC_LOW_##wc (X) & 7)) \
 277         _FP_FRAC_ADDI_##wc (X, _FP_WORK_LSB);   \
 278     }                                           \
 279   while (0)
 280
 281 #define _FP_ROUND(wc, X)                        \
 282   do                                            \
 283     {                                           \
 284       if (_FP_FRAC_LOW_##wc (X) & 7)            \
 285         {                                       \
 286           FP_SET_EXCEPTION (FP_EX_INEXACT);     \
 287           switch (FP_ROUNDMODE)                 \
 288             {                                   \
 289             case FP_RND_NEAREST:                \
 290               _FP_ROUND_NEAREST (wc, X);        \
 291               break;                            \
 292             case FP_RND_ZERO:                   \
 293               _FP_ROUND_ZERO (wc, X);           \
 294               break;                            \
 295             case FP_RND_PINF:                   \
 296               _FP_ROUND_PINF (wc, X);           \
 297               break;                            \
 298             case FP_RND_MINF:                   \
 299               _FP_ROUND_MINF (wc, X);           \
 300               break;                            \
 301             }                                   \
 302         }                                       \
 303     }                                           \
 304   while (0)
 305
 306 #define FP_CLS_NORMAL           0
 307 #define FP_CLS_ZERO             1
 308 #define FP_CLS_INF              2
 309 #define FP_CLS_NAN              3
 310
 311 #define _FP_CLS_COMBINE(x, y)   (((x) << 2) | (y))
 312
 313 #include "op-1.h"
 314 #include "op-2.h"
 315 #include "op-4.h"
 316 #include "op-8.h"
 317 #include "op-common.h"
 318
 319 /* Sigh.  Silly things longlong.h needs.  */
 320 #define UWtype          _FP_W_TYPE
 321 #define W_TYPE_SIZE     _FP_W_TYPE_SIZE
 322
 323 typedef int QItype __attribute__ ((mode (QI)));
 324 typedef int SItype __attribute__ ((mode (SI)));
 325 typedef int DItype __attribute__ ((mode (DI)));
 326 typedef unsigned int UQItype __attribute__ ((mode (QI)));
 327 typedef unsigned int USItype __attribute__ ((mode (SI)));
 328 typedef unsigned int UDItype __attribute__ ((mode (DI)));
 329 #if _FP_W_TYPE_SIZE == 32
 330 typedef unsigned int UHWtype __attribute__ ((mode (HI)));
 331 #elif _FP_W_TYPE_SIZE == 64
 332 typedef USItype UHWtype;
 333 #endif
 334
 335 #ifndef CMPtype
 336 # define CMPtype        int
 337 #endif
 338
 339 #define SI_BITS         (__CHAR_BIT__ * (int) sizeof (SItype))
 340 #define DI_BITS         (__CHAR_BIT__ * (int) sizeof (DItype))
 341
 342 #ifndef umul_ppmm
 343 # ifdef _LIBC
 344 #  include <stdlib/longlong.h>
 345 # else
 346 #  include "longlong.h"
 347 # endif
 348 #endif
 349
 350 #endif /* !SOFT_FP_H */