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];

    buffer[0] = 0xA5;                     // Start byte
    buffer[1] = command;                  // Command byte
    buffer[2] = value & 0xFF;             // Value LSB
    buffer[3] = (value >> 8) & 0xFF;      // Value MSB
    buffer[4] = status;                   // Status byte

    buffer[5] = checksum & 0xFF;          // Checksum byte 0 (LSB)
    buffer[6] = (checksum >> 8) & 0xFF;   // Checksum byte 1
    buffer[7] = (checksum >> 16) & 0xFF;  // Checksum byte 2
    buffer[8] = (checksum >> 24) & 0xFF;  // Checksum byte 3 (MSB)

    buffer[9] = 0x5A;                     // End byte

    // Print buffer contents
    for (int i = 0; i < 10; i++) {
        printf("%d ", buffer[i]);
    }
    printf("\n");
}
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

✅ Step-by-Step Solving Approach

1️⃣ Initialize the buffer

Create a uint8_t buffer[10] to hold the serialized packet.

2️⃣ Assign fixed values

• Set buffer[0] = 0xA5 (Start byte)
• Set buffer[9] = 0x5A (End byte)

3️⃣ Insert Command

• buffer[1] = command (1 byte)

4️⃣ Insert Value (2 bytes)

• Use bit masking and shifting:
  • buffer[2] = value & 0xFF → LSB
  • buffer[3] = (value >> 8) & 0xFF → MSB

5️⃣ Insert Status

• buffer[4] = status (1 byte)

6️⃣ Insert Checksum (4 bytes)

• Split 32-bit checksum into 4 bytes:
  • buffer[5] = checksum & 0xFF
  • buffer[6] = (checksum >> 8) & 0xFF
  • buffer[7] = (checksum >> 16) & 0xFF
  • buffer[8] = (checksum >> 24) & 0xFF

7️⃣ Print the buffer

Loop through buffer[0] to buffer[9] and print each byte as an integer.