58. Serialized Data Buffer

#include <stdio.h>
#include <stdint.h>

void build_packet(uint8_t command, uint16_t value, uint8_t status, uint32_t checksum) {
    uint8_t buffer[10];

    buffer[0] = 0xA5;           // Start
    buffer[1] = command;        // Command

    buffer[2] = value & 0xFF;         // LSB of value
    buffer[3] = (value >> 8) & 0xFF;  // MSB of value

    buffer[4] = status;         // Status
    
    buffer[5] = checksum & 0xFF;
    buffer[6] = (checksum >> 8) & 0xFF;
    buffer[7] = (checksum >> 16) & 0xFF;
    buffer[8] = (checksum >> 24) & 0xFF;

    buffer[9] = 0x5A;           // End

    for (int i = 0; i < 10; i++) {
        printf("%u", buffer[i]);
        if(i < 9){
            printf(" ");
        }
    }
}

int main() {
    uint8_t cmd, status;
    uint16_t val;
    uint32_t crc;
    scanf("%hhu %hu %hhu %u", &cmd, &val, &status, &crc);
    build_packet(cmd, val, status, crc);
    return 0;
}

🧠 What is Buffer Serialization?

In firmware, serialization means converting data fields into a sequential byte stream for transmission over hardware interfaces.
 

🎯 Why It Matters in Firmware?

• Needed for building UART, SPI, CAN packets
• Required when sending/receiving structured data
• Ensures byte alignment, order, and correctness
   

🔧 Solution Logic

• Start with a fixed-length byte buffer
• Store each field manually (LSB-first for integers)
• Print all 10 bytes in order