gcc/config/sh/divtab-sh4-300.c

   1 /* Copyright (C) 2004-2021 Free Software Foundation, Inc.
   2
   3 This file is free software; you can redistribute it and/or modify it
   4 under the terms of the GNU General Public License as published by the
   5 Free Software Foundation; either version 3, or (at your option) any
   6 later version.
   7
   8 This file is distributed in the hope that it will be useful, but
   9 WITHOUT ANY WARRANTY; without even the implied warranty of
  10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11 General Public License for more details.
  12
  13 Under Section 7 of GPL version 3, you are granted additional
  14 permissions described in the GCC Runtime Library Exception, version
  15 3.1, as published by the Free Software Foundation.
  16
  17 You should have received a copy of the GNU General Public License and
  18 a copy of the GCC Runtime Library Exception along with this program;
  19 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22
  23 /* Calculate division table for ST40-300 integer division
  24    Contributed by Joern Rennecke
  25    joern.rennecke@st.com  */
  26
  27 #include <stdio.h>
  28 #include <math.h>
  29
  30 int
  31 main ()
  32 {
  33   int i, j;
  34   double q, r, err, max_err = 0, max_s_err = 0;
  35
  36   puts("/* This table has been generated by divtab-sh4.c.  */");
  37   puts ("\t.balign 4");
  38   for (i = -128; i < 128; i++)
  39     {
  40       int n = 0;
  41       if (i == 0)
  42         {
  43           /* output some dummy number for 1/0.  */
  44           puts ("LOCAL(div_table_clz):\n\t.byte\t0");
  45           continue;
  46         }
  47       for (j = i < 0 ? -i : i; j < 128; j += j)
  48         n++;
  49       printf ("\t.byte\t%d\n", n - 7);
  50     }
  51   puts("\
  52 /* 1/-128 .. 1/127, normalized.  There is an implicit leading 1 in bit 32,\n\
  53    or in bit 33 for powers of two.  */\n\
  54         .balign 4");
  55   for (i = -128; i < 128; i++)
  56     {
  57       if (i == 0)
  58         {
  59           puts ("LOCAL(div_table_inv):\n\t.long\t0x0");
  60           continue;
  61         }
  62       j = i < 0 ? -i : i;
  63       while (j < 64)
  64         j += j;
  65       q = 4.*(1<<30)*128/j;
  66       r = ceil (q);
  67       printf ("\t.long\t0x%X\n", (unsigned) r);
  68       err = r - q;
  69       if (err > max_err)
  70         max_err = err;
  71       err = err * j / 128;
  72       if (err > max_s_err)
  73         max_s_err = err;
  74     }
  75   printf ("\t/* maximum error: %f scaled: %f*/\n", max_err, max_s_err);
  76   exit (0);
  77 }