git.zerfleddert.de Git - proxmark3-svn/blob - client/reveng/bmpbit.c

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