client/deps/reveng/bmpbit.c

   1 /* bmpbit.c
   2  * Greg Cook, 23/Feb/2019
   3  */
   4
   5 /* CRC RevEng: arbitrary-precision CRC calculator and algorithm finder
   6  * Copyright (C) 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018,
   7  * 2019  Gregory Cook
   8  *
   9  * This file is part of CRC RevEng.
  10  *
  11  * CRC RevEng is free software: you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation, either version 3 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * CRC RevEng is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with CRC RevEng.  If not, see <https://www.gnu.org/licenses/>.
  23  */
  24
  25 #ifdef BMPTST
  26 #  include <stdio.h>
  27 #  include <stdlib.h>
  28 #else
  29 #  define FILE void
  30 #endif
  31 #include "reveng.h"
  32
  33 #ifdef BMPTST
  34 #  undef fprintf
  35 #  undef puts
  36 #  undef fputs
  37 #endif
  38
  39 #if (defined BMPTST) || (BMP_BIT < 32)
  40 /* Size in bits of a bmp_t.  Not necessarily a power of two. */
  41 int bmpbit;
  42
  43 /* The highest power of two that is strictly less than BMP_BIT.
  44  * Initialises the index of a binary search for set bits in a bmp_t.
  45  * (Computed correctly for BMP_BIT >= 2)
  46  */
  47 int bmpsub;
  48
  49 void
  50 setbmp(void) {
  51     /* Initialise BMP_BIT and BMP_SUB for the local architecture. */
  52     bmp_t bmpmax = ~(bmp_t) 0;
  53
  54     bmpbit = 0;
  55     bmpsub = 1;
  56
  57     while (bmpmax) {
  58         bmpmax <<= 1;
  59         ++bmpbit;
  60     }
  61
  62     while ((bmpsub | (bmpsub - 1)) < bmpbit - 1)
  63         bmpsub <<= 1;
  64 }
  65 #endif
  66
  67 #ifdef BMPTST
  68 int
  69 main(int argc, char *argv[]) {
  70     /* check the compile-time bitmap width is correct, otherwise
  71      * searches run forever. */
  72 #  if BMP_BIT > 0
  73     setbmp();
  74     if (BMP_BIT != bmpbit || BMP_SUB != bmpsub) {
  75         fprintf(stderr, "reveng: configuration fault.  Update "
  76                 "reveng/config.h with these definitions and "
  77                 "recompile:\n"
  78                 "\t#define BMP_BIT   %d\n"
  79                 "\t#define BMP_SUB   %d\n",
  80                 bmpbit, bmpsub);
  81         exit(EXIT_FAILURE);
  82     }
  83 #  endif /* BMP_BIT > 0 */
  84     /* check the bitmap constant macro */
  85     if (~(bmp_t) 0 != ~BMP_C(0)) {
  86         fprintf(stderr, "reveng: configuration fault.  Edit "
  87                 "the definition of BMP_C() in config.h to "
  88                 "match BMP_T and recompile.\n");
  89         exit(EXIT_FAILURE);
  90     }
  91     exit(EXIT_SUCCESS);
  92 }
  93
  94 #endif /* BMPTST */