diff options
author | Stig Bjørlykke <stig@bjorlykke.org> | 2011-08-30 13:46:42 +0000 |
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committer | Stig Bjørlykke <stig@bjorlykke.org> | 2011-08-30 13:46:42 +0000 |
commit | 4132d40e50c576ae6cf9e03e4f552ea091035626 (patch) | |
tree | 4b1f8343011ca58ba5cd44782166f029cc7e3a8b /wsutil/crcdrm.c | |
parent | bb67b92a14c502e2c9841863dbbef869818f3e58 (diff) |
Move all crc routines to libwsutil.
This way we can use the crc routines in wiretap.
svn path=/trunk/; revision=38800
Diffstat (limited to 'wsutil/crcdrm.c')
-rw-r--r-- | wsutil/crcdrm.c | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/wsutil/crcdrm.c b/wsutil/crcdrm.c new file mode 100644 index 0000000000..345a232bb9 --- /dev/null +++ b/wsutil/crcdrm.c @@ -0,0 +1,50 @@ +/* crcdrm.c + * another CRC 16 + * Copyright 2006, British Broadcasting Corporation + * + * $Id$ + * + * Wireshark - Network traffic analyzer + * By Gerald Combs <gerald@wireshark.org> + * Copyright 1998 Gerald Combs + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + */ + + +#include "crcdrm.h" + +unsigned long crc_drm(const char *data, size_t bytesize, + unsigned short num_crc_bits, unsigned long crc_gen, int invert) +{ + unsigned long crc_holder, ones, i, msb, databit; + signed short j; + + ones = (1 << num_crc_bits) - 1; + crc_holder = ones; + for (i=0; i<bytesize; i++) + for (j=7; j>=0; j--) + { + crc_holder <<= 1; + msb = crc_holder >> num_crc_bits; + databit = (data[i] >> j) & 1; + if ((msb ^ databit) != 0) + crc_holder = crc_holder ^ crc_gen; + crc_holder = crc_holder & ones; + } + if (invert) + crc_holder = crc_holder ^ ones; /* invert checksum */ + return crc_holder; +} |