45. Serialized Data Buffer

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

void split_bytes(uint32_t reg, uint8_t num_byte, uint8_t *arr){
    uint8_t mask = (1<<8)-1;
    for(uint8_t i=0; i<num_byte; i++){
        arr[i] = (reg>>(8*i))&mask; 
    }
}

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

    // Your logic to fill buffer
    // Then print buffer
    uint8_t var1[2], var2[4];
    uint8_t start = 0xA5, end = 0x5A;
    buffer[0] = start; buffer[9] = end;
    buffer[1] = command;
    buffer[4] = status;
    split_bytes(value, 2, var1);
    buffer[2] = var1[0];
    buffer[3] = var1[1];
    split_bytes(checksum, 4, var2);
    for(uint8_t i=0; i<4; i++){
        buffer[5+i] = var2[i];
    }
    for(uint8_t i=0; i<10; i++){
        printf("%d ", buffer[i]);
    }
}

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;
}