release/src/router/mysql/storage/myisam/mi_checksum.c

   1 /* Copyright (c) 2000, 2001, 2003-2007 MySQL AB
   2
   3    This program is free software; you can redistribute it and/or modify
   4    it under the terms of the GNU General Public License as published by
   5    the Free Software Foundation; version 2 of the License.
   6
   7    This program is distributed in the hope that it will be useful,
   8    but WITHOUT ANY WARRANTY; without even the implied warranty of
   9    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10    GNU General Public License for more details.
  11
  12    You should have received a copy of the GNU General Public License
  13    along with this program; if not, write to the Free Software
  14    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA */
  15
  16 /* Calculate a checksum for a row */
  17
  18 #include "myisamdef.h"
  19
  20 ha_checksum mi_checksum(MI_INFO *info, const uchar *buf)
  21 {
  22   uint i;
  23   ha_checksum crc=0;
  24   MI_COLUMNDEF *rec=info->s->rec;
  25
  26   for (i=info->s->base.fields ; i-- ; buf+=(rec++)->length)
  27   {
  28     const uchar *pos;
  29     ulong length;
  30     switch (rec->type) {
  31     case FIELD_BLOB:
  32     {
  33       length=_mi_calc_blob_length(rec->length-
  34                                         portable_sizeof_char_ptr,
  35                                         buf);
  36       memcpy((char*) &pos, buf+rec->length- portable_sizeof_char_ptr,
  37              sizeof(char*));
  38       break;
  39     }
  40     case FIELD_VARCHAR:
  41     {
  42       uint pack_length= HA_VARCHAR_PACKLENGTH(rec->length-1);
  43       if (pack_length == 1)
  44         length= (ulong) *(uchar*) buf;
  45       else
  46         length= uint2korr(buf);
  47       pos= buf+pack_length;
  48       break;
  49     }
  50     default:
  51       length=rec->length;
  52       pos=buf;
  53       break;
  54     }
  55     crc=my_checksum(crc, pos ? pos : (uchar*) "", length);
  56   }
  57   return crc;
  58 }
  59
  60
  61 ha_checksum mi_static_checksum(MI_INFO *info, const uchar *pos)
  62 {
  63   return my_checksum(0, pos, info->s->base.reclength);
  64 }