SpaceWire-RMAP CRC calculation example

crc_example.cc

#include <iostream>
#include <vector>

static const uint8_t RMAP_CRC_TABLE[] = {
    0x00, 0x91, 0xe3, 0x72, 0x07, 0x96, 0xe4, 0x75,  // 0
    0x0e, 0x9f, 0xed, 0x7c, 0x09, 0x98, 0xea, 0x7b,  // 1
    0x1c, 0x8d, 0xff, 0x6e, 0x1b, 0x8a, 0xf8, 0x69,  // 2
    0x12, 0x83, 0xf1, 0x60, 0x15, 0x84, 0xf6, 0x67,  // 3
    0x38, 0xa9, 0xdb, 0x4a, 0x3f, 0xae, 0xdc, 0x4d,  // 4
    0x36, 0xa7, 0xd5, 0x44, 0x31, 0xa0, 0xd2, 0x43,  // 5
    0x24, 0xb5, 0xc7, 0x56, 0x23, 0xb2, 0xc0, 0x51,  // 6
    0x2a, 0xbb, 0xc9, 0x58, 0x2d, 0xbc, 0xce, 0x5f,  // 7
    0x70, 0xe1, 0x93, 0x02, 0x77, 0xe6, 0x94, 0x05,  // 8
    0x7e, 0xef, 0x9d, 0x0c, 0x79, 0xe8, 0x9a, 0x0b,  // 9
    0x6c, 0xfd, 0x8f, 0x1e, 0x6b, 0xfa, 0x88, 0x19,  // 10
    0x62, 0xf3, 0x81, 0x10, 0x65, 0xf4, 0x86, 0x17,  // 11
    0x48, 0xd9, 0xab, 0x3a, 0x4f, 0xde, 0xac, 0x3d,  // 12
    0x46, 0xd7, 0xa5, 0x34, 0x41, 0xd0, 0xa2, 0x33,  // 13
    0x54, 0xc5, 0xb7, 0x26, 0x53, 0xc2, 0xb0, 0x21,  // 14
    0x5a, 0xcb, 0xb9, 0x28, 0x5d, 0xcc, 0xbe, 0x2f,  // 15

    0xe0, 0x71, 0x03, 0x92, 0xe7, 0x76, 0x04, 0x95,  // 16
    0xee, 0x7f, 0x0d, 0x9c, 0xe9, 0x78, 0x0a, 0x9b,  // 17
    0xfc, 0x6d, 0x1f, 0x8e, 0xfb, 0x6a, 0x18, 0x89,  // 18
    0xf2, 0x63, 0x11, 0x80, 0xf5, 0x64, 0x16, 0x87,  // 19
    0xd8, 0x49, 0x3b, 0xaa, 0xdf, 0x4e, 0x3c, 0xad,  // 20
    0xd6, 0x47, 0x35, 0xa4, 0xd1, 0x40, 0x32, 0xa3,  // 21
    0xc4, 0x55, 0x27, 0xb6, 0xc3, 0x52, 0x20, 0xb1,  // 22
    0xca, 0x5b, 0x29, 0xb8, 0xcd, 0x5c, 0x2e, 0xbf,  // 23
    0x90, 0x01, 0x73, 0xe2, 0x97, 0x06, 0x74, 0xe5,  // 24
    0x9e, 0x0f, 0x7d, 0xec, 0x99, 0x08, 0x7a, 0xeb,  // 25
    0x8c, 0x1d, 0x6f, 0xfe, 0x8b, 0x1a, 0x68, 0xf9,  // 26
    0x82, 0x13, 0x61, 0xf0, 0x85, 0x14, 0x66, 0xf7,  // 27
    0xa8, 0x39, 0x4b, 0xda, 0xaf, 0x3e, 0x4c, 0xdd,  // 28
    0xa6, 0x37, 0x45, 0xd4, 0xa1, 0x30, 0x42, 0xd3,  // 29
    0xb4, 0x25, 0x57, 0xc6, 0xb3, 0x22, 0x50, 0xc1,  // 30
    0xba, 0x2b, 0x59, 0xc8, 0xbd, 0x2c, 0x5e, 0xcf   // 31
};

uint8_t calculate_crc(const std::vector<uint8_t>& data) {
  uint8_t crc = 0x00;
  const size_t length = data.size();
  for (size_t i = 0; i < length; i++) {
    const uint8_t crc_new = RMAP_CRC_TABLE[(crc ^ data[i]) & 0xff];
    crc = crc_new;
  }
  return crc;
}

int main(int argc, char* argv[]) {
  // Command
  std::vector<uint8_t> command_packet = {0xfe, 0x01, 0x7c, 0x00, 0xfe,
                                         0x00, 0x00, 0x00, 0x01, 0x01,
                                         0x10, 0x04, 0x00, 0x00, 0x02};
  printf("CRC = 0x%02x\n", calculate_crc(command_packet));

  // Reply
  std::vector<uint8_t> reply_packet = {0xfe, 0x01, 0x3c, 0x00,
                                       0xfe, 0x00, 0x05, 0x2f};
  printf("CRC = 0x%02x\n", calculate_crc(reply_packet));
}

Makefile

all: crc_example
crc_example: crc_example.cc
	clang++ -std=c++11 -stdlib=libc++ $^ -o $@