// VARIANT A: presumably easier to implement on little endian machines

uint32_t crctab32[256]; // lookup table

uint32_t CRC32_Backward(char *array, int16_t N){ // input is array of N octets

// containing the data,
see Figure 23

uint32_t result = 1; // seed value for the calculated CRC

int16_t i; // index

for(i=N-1;i>=0;i--) // process array in reversed order

result = crctab32 [((result >> 24) ^ array[i]) & 0xff] ^ (result << 8);

if (result==0)
return 1;
else
return result;

}

// VARIANT B: presumably easier to implement on big endian machines

uint32_t crctab32[256]; // lookup table

uint32_t CRC32_Forward(char *array, int16_t N){ // input is array of N octets

// containing the data in reversed

// order, see e. g. Figure 24

uint32_t result = 1; // seed value for the calculated CRC

int16_t i; // index

for(i=0;i<N;i++) // process array

result = crctab32 [((result >> 24) ^ array[i]) & 0xff] ^ (result << 8);

if (result==0)
return 1;
else
return result;

}