sysdeps/ieee754/flt-32/s_truncf.c

   1 /* Truncate argument to nearest integral value not larger than the argument.
   2    Copyright (C) 1997-2024 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    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #define NO_MATH_REDIRECT
  20 #include <math.h>
  21
  22 #include <math_private.h>
  23 #include <libm-alias-float.h>
  24 #include <math-use-builtins.h>
  25
  26
  27 float
  28 __truncf (float x)
  29 {
  30 #if USE_TRUNCF_BUILTIN
  31   return __builtin_truncf (x);
  32 #else
  33   /* Use generic implementation.  */
  34   int32_t i0, j0;
  35   int sx;
  36
  37   GET_FLOAT_WORD (i0, x);
  38   sx = i0 & 0x80000000;
  39   j0 = ((i0 >> 23) & 0xff) - 0x7f;
  40   if (j0 < 23)
  41     {
  42       if (j0 < 0)
  43         /* The magnitude of the number is < 1 so the result is +-0.  */
  44         SET_FLOAT_WORD (x, sx);
  45       else
  46         SET_FLOAT_WORD (x, sx | (i0 & ~(0x007fffff >> j0)));
  47     }
  48   else
  49     {
  50       if (j0 == 0x80)
  51         /* x is inf or NaN.  */
  52         return x + x;
  53     }
  54
  55   return x;
  56 #endif /* ! USE_TRUNCF_BUILTIN  */
  57 }
  58 #ifndef __truncf
  59 libm_alias_float (__trunc, trunc)
  60 #endif