lib/setpayloadsigl.c

   1 /* Construct a signalling NaN 'long double' with a given payload.
   2    Copyright 2024-2025 Free Software Foundation, Inc.
   3
   4    This file is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation, either version 3 of the
   7    License, or (at your option) any later version.
   8
   9    This file is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Bruno Haible.  */
  18
  19 #include <config.h>
  20
  21 /* Specification.  */
  22 #include <math.h>
  23
  24 #if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
  25
  26 int
  27 setpayloadsigl (long double *result, long double payload)
  28 {
  29   return setpayloadsig ((double *) result, payload);
  30 }
  31
  32 #else
  33
  34 # include <float.h>
  35 # include <stdint.h>
  36
  37 # include "signed-snan.h"
  38
  39 /* 2^(LDBL_MANT_DIG-1).  */
  40 # define TWO_LDBL_MANT_DIG \
  41     ((long double) (1U << ((LDBL_MANT_DIG - 1) / 4)) \
  42      * (long double) (1U << ((LDBL_MANT_DIG - 1 + 1) / 4)) \
  43      * (long double) (1U << ((LDBL_MANT_DIG - 1 + 2) / 4)) \
  44      * (long double) (1U << ((LDBL_MANT_DIG - 1 + 3) / 4)))
  45
  46 int
  47 setpayloadsigl (long double *result, long double payload)
  48 {
  49 # if (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 106 || LDBL_MANT_DIG == 113) \
  50      && defined LDBL_EXPBIT0_WORD && defined LDBL_EXPBIT0_BIT
  51   if (
  52 #  if defined __hppa || (defined __mips__ && !MIPS_NAN2008_LONG_DOUBLE) || defined __sh__
  53       payload >= 0.0L
  54 #  else
  55       /* A zero payload is not allowed, because that would denote Infinity.
  56          Cf. snan.h.  */
  57       payload > 0.0L
  58 #  endif
  59 #  if LDBL_MANT_DIG == 64 /* on i386, x86_64, ia64, m68k */
  60       && payload < 4611686018427387904.0L /* exp2l (LDBL_MANT_DIG - 2) */
  61       && payload == (long double) (int64_t) payload
  62 #  endif
  63 #  if LDBL_MANT_DIG == 106 /* on powerpc, powerpc64, powerpc64le */
  64       && payload < 2251799813685248.0L /* exp2l (DBL_MANT_DIG - 2) */
  65       && payload == (long double) (int64_t) payload
  66 #  endif
  67 #  if LDBL_MANT_DIG == 113 /* on alpha, arm64, loongarch64, mips64, riscv64, s390x, sparc64 */
  68       && payload < 2596148429267413814265248164610048.0L /* exp2l (LDBL_MANT_DIG - 2) */
  69       && payload == +(+(payload + TWO_LDBL_MANT_DIG) - TWO_LDBL_MANT_DIG)
  70 #  endif
  71      )
  72     {
  73       memory_long_double x = memory_positive_SNaNl ();
  74
  75 #  if LDBL_MANT_DIG == 64 /* on i386, x86_64, ia64, m68k */
  76       uint64_t pl = (int64_t) payload;
  77 #   if LDBL_EXPBIT0_WORD == 2 && LDBL_EXPBIT0_BIT == 0 /* on i386, x86_64, ia64 */
  78       x.word[1] = (x.word[1] & 0xC0000000U) | (uint32_t) (pl >> 32);
  79       x.word[0] = (uint32_t) pl;
  80 #   elif LDBL_EXPBIT0_WORD == 0 && LDBL_EXPBIT0_BIT == 16 /* on m68k */
  81       x.word[1] = (x.word[1] & 0xC0000000U) | (uint32_t) (pl >> 32);
  82       x.word[2] = (uint32_t) pl;
  83 #   else
  84 #    error "Please port gnulib setpayloadsigl.c to your platform!"
  85 #   endif
  86 #  endif
  87 #  if LDBL_MANT_DIG == 106 /* on powerpc, powerpc64, powerpc64le */
  88       uint64_t pl = (int64_t) payload;
  89 #   if LDBL_EXPBIT0_BIT == 20
  90       uint32_t pl_hi = (uint32_t) (pl >> 32);
  91       uint32_t pl_lo = (uint32_t) pl;
  92       x.word[LDBL_EXPBIT0_WORD] = (x.word[LDBL_EXPBIT0_WORD] & 0xFFF80000U)
  93                                   | pl_hi;
  94       x.word[LDBL_EXPBIT0_WORD + (LDBL_EXPBIT0_WORD == 0 ? 1 : -1)] = pl_lo;
  95 #   else
  96 #    error "Please port gnulib setpayloadsigl.c to your platform!"
  97 #   endif
  98 #  endif
  99 #  if LDBL_MANT_DIG == 113 /* on alpha, arm64, loongarch64, mips64, riscv64, s390x, sparc64 */
 100 #   if LDBL_EXPBIT0_BIT == 16
 101       memory_long_double pl;
 102       pl.value = payload + TWO_LDBL_MANT_DIG;
 103       x.word[LDBL_EXPBIT0_WORD] = (x.word[LDBL_EXPBIT0_WORD] & 0xFFFF8000U)
 104                                   | (pl.word[LDBL_EXPBIT0_WORD] & 0x00007FFFU);
 105       x.word[LDBL_EXPBIT0_WORD + (LDBL_EXPBIT0_WORD == 0 ? 1 : -1)] =
 106         pl.word[LDBL_EXPBIT0_WORD + (LDBL_EXPBIT0_WORD == 0 ? 1 : -1)];
 107       x.word[LDBL_EXPBIT0_WORD + (LDBL_EXPBIT0_WORD == 0 ? 2 : -2)] =
 108         pl.word[LDBL_EXPBIT0_WORD + (LDBL_EXPBIT0_WORD == 0 ? 2 : -2)];
 109       x.word[LDBL_EXPBIT0_WORD + (LDBL_EXPBIT0_WORD == 0 ? 3 : -3)] =
 110         pl.word[LDBL_EXPBIT0_WORD + (LDBL_EXPBIT0_WORD == 0 ? 3 : -3)];
 111 #   else
 112 #    error "Please port gnulib setpayloadsigl.c to your platform!"
 113 #   endif
 114 #  endif
 115
 116       *result = x.value;
 117       return 0;
 118     }
 119   else
 120     {
 121       *result = 0.0L;
 122       return -1;
 123     }
 124 # else
 125 #  error "Please port gnulib setpayloadsigl.c to your platform!"
 126 # endif
 127 }
 128
 129 #endif