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monitor: Add functions for link layer CRC calculations

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This commit is contained in:
Marcel Holtmann 2013-08-21 23:04:59 -07:00
parent 6e8cf9a167
commit 6915f9bf88
2 changed files with 114 additions and 0 deletions
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84
monitor/crc.c Normal file
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/*
*
* BlueZ - Bluetooth protocol stack for Linux
*
* Copyright (C) 2011-2012 Intel Corporation
* Copyright (C) 2004-2010 Marcel Holtmann <marcel@holtmann.org>
*
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "crc.h"
uint32_t crc24_bit_reverse(uint32_t value)
{
uint32_t result = 0;
uint8_t i;
for (i = 0; i < 24; i++)
result |= ((value >> i) & 1) << (23 - i);
return result;
}
uint32_t crc24_calculate(uint32_t preset, const uint8_t *data, uint8_t len)
{
uint32_t state = preset;
uint8_t i;
for (i = 0; i < len; i++) {
uint8_t n, cur = data[i];
for (n = 0; n < 8; n++) {
int next_bit = (state ^ cur) & 1;
cur >>= 1;
state >>= 1;
if (next_bit) {
state |= 1 << 23;
state ^= 0x5a6000;
}
}
}
return state;
}
uint32_t crc24_reverse(uint32_t crc, const uint8_t *data, uint8_t len)
{
uint32_t state = crc;
uint8_t i;
for (i = 0; i < len; i++) {
uint8_t n, cur = data[len - i - 1];
for (n = 0; n < 8; n++) {
int top_bit = state >> 23;
state = (state << 1) & 0xffffff;
state |= top_bit ^ ((cur >> (7 - n)) & 1);
if (top_bit)
state ^= 0xb4c000;
}
}
return state;
}

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monitor/crc.h Normal file
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/*
*
* BlueZ - Bluetooth protocol stack for Linux
*
* Copyright (C) 2011-2012 Intel Corporation
* Copyright (C) 2004-2010 Marcel Holtmann <marcel@holtmann.org>
*
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include <stdint.h>
uint32_t crc24_bit_reverse(uint32_t value);
uint32_t crc24_calculate(uint32_t preset, const uint8_t *data, uint8_t len);
uint32_t crc24_reverse(uint32_t crc, const uint8_t *data, uint8_t len);