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1 /* Copyright (C) 2004-2018 Free Software Foundation, Inc.
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2
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3 This file is free software; you can redistribute it and/or modify it
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4 under the terms of the GNU General Public License as published by the
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5 Free Software Foundation; either version 3, or (at your option) any
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6 later version.
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7
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8 This file is distributed in the hope that it will be useful, but
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9 WITHOUT ANY WARRANTY; without even the implied warranty of
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10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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11 General Public License for more details.
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12
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13 Under Section 7 of GPL version 3, you are granted additional
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14 permissions described in the GCC Runtime Library Exception, version
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15 3.1, as published by the Free Software Foundation.
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16
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17 You should have received a copy of the GNU General Public License and
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18 a copy of the GCC Runtime Library Exception along with this program;
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19 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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20 <http://www.gnu.org/licenses/>. */
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21
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22 /* Calculate division table for SH2..4 integer division
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23 Contributed by Joern Rernnecke
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24 joern.rennecke@superh.com */
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25
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26 #include <stdio.h>
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27 #include <math.h>
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28
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29 int
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30 main ()
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31 {
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32 int i, j;
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33 double q, r, err, max_err = 0, max_s_err = 0;
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34
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35 puts("/* This table has been generated by divtab-sh4.c. */");
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36 puts ("\t.balign 4");
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37 puts ("LOCAL(div_table_clz):");
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38 /* output some dummy number for 1/0. */
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39 printf ("\t.byte\t%d\n", 0);
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40 for (i = 1; i <= 128; i++)
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41 {
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42 int n = 0;
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43 if (i == 128)
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44 puts ("\
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45 /* Lookup table translating positive divisor to index into table of\n\
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46 normalized inverse. N.B. the '0' entry is also the last entry of the\n\
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47 previous table, and causes an unaligned access for division by zero. */\n\
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48 LOCAL(div_table_ix):");
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49 for (j = i; j <= 128; j += j)
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50 n++;
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51 printf ("\t.byte\t%d\n", n - 7);
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52 }
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53 for (i = 1; i <= 128; i++)
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54 {
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55 j = i < 0 ? -i : i;
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56 while (j < 128)
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57 j += j;
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58 printf ("\t.byte\t%d\n", j * 2 - 96*4);
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59 }
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60 puts("\
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61 /* 1/64 .. 1/127, normalized. There is an implicit leading 1 in bit 32. */\n\
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62 .balign 4\n\
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63 LOCAL(zero_l):");
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64 for (i = 64; i < 128; i++)
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65 {
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66 if (i == 96)
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67 puts ("LOCAL(div_table):");
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68 q = 4.*(1<<30)*128/i;
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69 r = ceil (q);
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70 /* The value for 64 is actually differently scaled that it would
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71 appear from this calculation. The implicit part is %01, not 10.
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72 Still, since the value in the table is 0 either way, this
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73 doesn't matter here. Still, the 1/64 entry is effectively a 1/128
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74 entry. */
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75 printf ("\t.long\t0x%X\n", (unsigned) r);
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76 err = r - q;
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77 if (err > max_err)
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78 max_err = err;
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79 err = err * i / 128;
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80 if (err > max_s_err)
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81 max_s_err = err;
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82 }
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83 printf ("\t/* maximum error: %f scaled: %f*/\n", max_err, max_s_err);
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84 exit (0);
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85 }
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