Serialized Data Buffer

Code

#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];
    uint8_t *p = buffer;
    int i = 0;
    /*
    Due to data alignment of the data structure,
    you can't use union.
    */
    *p++ = 0xa5;
    *p++ = command;
    *(uint16_t *)p = value;
    p += 2;
    *p++ = status;
    *(uint32_t *)p = checksum;
    p += 4;
    *p = 0x5a;
    while (i < 10)
        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;
}

Solving Approach