src/main/common/crc.c

   1 /*
   2  * This file is part of Cleanflight.
   3  *
   4  * Cleanflight is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * Cleanflight is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <stdint.h>
  19
  20 #include "crc.h"
  21 #include "streambuf.h"
  22
  23
  24 uint16_t crc16_ccitt(uint16_t crc, unsigned char a)
  25 {
  26     crc ^= (uint16_t)a << 8;
  27     for (int ii = 0; ii < 8; ++ii) {
  28         if (crc & 0x8000) {
  29             crc = (crc << 1) ^ 0x1021;
  30         } else {
  31             crc = crc << 1;
  32         }
  33     }
  34     return crc;
  35 }
  36
  37 uint16_t crc16_ccitt_update(uint16_t crc, const void *data, uint32_t length)
  38 {
  39     const uint8_t *p = (const uint8_t *)data;
  40     const uint8_t *pend = p + length;
  41
  42     for (; p != pend; p++) {
  43         crc = crc16_ccitt(crc, *p);
  44     }
  45     return crc;
  46 }
  47
  48 void crc16_ccitt_sbuf_append(sbuf_t *dst, uint8_t *start)
  49 {
  50     uint16_t crc = 0;
  51     const uint8_t * const end = sbufPtr(dst);
  52     for (const uint8_t *ptr = start; ptr < end; ++ptr) {
  53         crc = crc16_ccitt(crc, *ptr);
  54     }
  55     sbufWriteU16(dst, crc);
  56 }
  57
  58 uint8_t crc8_dvb_s2(uint8_t crc, unsigned char a)
  59 {
  60     crc ^= a;
  61     for (int ii = 0; ii < 8; ++ii) {
  62         if (crc & 0x80) {
  63             crc = (crc << 1) ^ 0xD5;
  64         } else {
  65             crc = crc << 1;
  66         }
  67     }
  68     return crc;
  69 }
  70
  71 uint8_t crc8_dvb_s2_update(uint8_t crc, const void *data, uint32_t length)
  72 {
  73     const uint8_t *p = (const uint8_t *)data;
  74     const uint8_t *pend = p + length;
  75
  76     for (; p != pend; p++) {
  77         crc = crc8_dvb_s2(crc, *p);
  78     }
  79     return crc;
  80 }
  81
  82 void crc8_dvb_s2_sbuf_append(sbuf_t *dst, uint8_t *start)
  83 {
  84     uint8_t crc = 0;
  85     const uint8_t * const end = dst->ptr;
  86     for (const uint8_t *ptr = start; ptr < end; ++ptr) {
  87         crc = crc8_dvb_s2(crc, *ptr);
  88     }
  89     sbufWriteU8(dst, crc);
  90 }
  91
  92 uint8_t crc8_xor_update(uint8_t crc, const void *data, uint32_t length)
  93 {
  94     const uint8_t *p = (const uint8_t *)data;
  95     const uint8_t *pend = p + length;
  96
  97     for (; p != pend; p++) {
  98         crc ^= *p;
  99     }
 100     return crc;
 101 }
 102
 103 void crc8_xor_sbuf_append(sbuf_t *dst, uint8_t *start)
 104 {
 105     uint8_t crc = 0;
 106     const uint8_t *end = dst->ptr;
 107     for (uint8_t *ptr = start; ptr < end; ++ptr) {
 108         crc ^= *ptr;
 109     }
 110     sbufWriteU8(dst, crc);
 111 }
 112
 113 uint8_t crc8(uint8_t crc, uint8_t a)
 114 {
 115     uint8_t crc_u = a;
 116     crc_u ^= crc;
 117
 118     for (int i=0; i<8; i++) {
 119         crc_u = ( crc_u & 0x80 ) ? 0x7 ^ ( crc_u << 1 ) : ( crc_u << 1 );
 120     }
 121
 122     return crc_u;
 123 }
 124
 125 uint8_t crc8_update(uint8_t crc, const void *data, uint32_t length)
 126 {
 127     const uint8_t *p = (const uint8_t *)data;
 128     const uint8_t *pend = p + length;
 129
 130     for (; p != pend; p++) {
 131         crc = crc8(crc, *p);
 132     }
 133     return crc;
 134 }
 135
 136 uint8_t crc8_sum_update(uint8_t crc, const void *data, uint32_t length)
 137 {
 138     const uint8_t *p = (const uint8_t *)data;
 139     const uint8_t *pend = p + length;
 140
 141     for (; p != pend; p++) {
 142         crc += *p;
 143     }
 144     return crc;
 145 }