CRC coding calculation method and C language implementation
CRC (Cyclic Redundancy Check) is a commonly used error checking code used to detect and correct errors during transmission. In data communication and storage, CRC encoding is widely used because of its efficient error detection and easy implementation.
CRC coding calculation method and C language implementation
The calculation method of CRC encoding is based on the division operation of polynomials, where polynomials are called generator polynomials. The coefficients of the generator polynomial determine the performance and fault tolerance of CRC encoding. In CRC encoding, the data is divided by the generator polynomial, and the remainder is appended to the data as a check code for transmission. The receiver divides the data and the attached check code. If the remainder is 0, it means that no errors occurred during the data transmission.
The following will introduce a commonly used CRC encoding calculation method and its C language implementation. Assuming that the generating polynomial is G(x), the data is D(x), and the check code is R(x), the calculation process of CRC encoding can be decomposed into the following steps:
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Initialization: Set all coefficients of R(x) to 0, so that the initial value of R(x) is all 0.
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Process the data: expand the number of coefficients of data D(x) to the number of coefficients of G(x) plus the highest power of R(x). This can be achieved using the left shift operator <<. <>
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Perform division operation: divide the data D(x) by the generator polynomial G(x) through the modulo 2 division operation, and the resulting remainder is stored in R(x). The specific division operation can be implemented by looping through the coefficients of D(x) and G(x).
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Loop operation: Repeat the division operation in step 3 until all data bits have been traversed.
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Result processing: append the coefficient of R(x) as a check code to the back of the data D(x) to obtain the CRC-encoded data.
The following is a sample code that implements CRC encoding calculation in C language:
#include
//generate polynomial
#define GENERATOR_POLY 0x04C11DB7
// Calculate CRC code
unsigned int calculate_crc(unsigned char data[], int length) {
unsigned int crc = 0xFFFFFFFF;
for (int i = 0; i < length; i++) {
crc ^= (data[i] << 24=“”>
for (int j = 0; j < 8; j++) {
if (crc & 0x80000000) {
crc = (crc << 1=“”>
} else {
crc <<= 1=“”>
}
}
}
return crc;
}
int main() {
unsigned char data[] = {0x01, 0x02, 0x03, 0x04};
int length = sizeof(data) / sizeof(data[0]);
unsigned int crc = calculate_crc(data, length);
printf(\CRC: %08X\
\ crc);
return 0;
}
The above code implements CRC encoding calculation for data {0x01, 0x02, 0x03, 0x04} and prints out the calculated check code.
Through the introduction of this article, we understand the calculation method of CRC encoding and implement the calculation process of CRC encoding using C language. As an efficient error checking code, CRC encoding can help us detect and correct errors during transmission. After mastering the calculation method and implementation of CRC coding, we can apply CRC coding in data communication and storage to improve the reliability and stability of data transmission.
Part of the code is transferred from: https://www.songxinke.com/c/2023-08/255778.html