Extract Packet Fields from Byte Stream

Cast buffer to struct pntr

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

struct Packet{
    uint8_t start;
    uint8_t cmd;
    uint16_t data;
    uint8_t crc;
    uint8_t end;
};

void print_packet_fields(uint8_t *buffer) {
    // Overlay struct and print values
/*    pack.start = *(buffer + 0);
    pack.cmd =   *(buffer + 1); 
    pack.data =  *(uint16_t*)(buffer + 2); 
    pack.crc =   *(buffer + 4); 
    pack.end =   *(buffer + 5); 
  
    printf("Start: %d", pack.start);
    printf("\nCommand: %d", pack.cmd);
    printf("\nData: %d", pack.data);
    printf("\nCRC: %d", pack.crc);
    printf("\nEnd: %d", pack.end);

*/
    struct Packet *pntr = (Packet*)buffer;
    printf("Start: %d", pntr->start);
    printf("\nCommand: %d", pntr->cmd);
    printf("\nData: %d", pntr->data);
    printf("\nCRC: %d", pntr->crc);
    printf("\nEnd: %d", pntr->end);
}

int main() {
    uint8_t buffer[6];
    for (int i = 0; i < 6; i++) {
        scanf("%hhu", &buffer[i]);
    }
    print_packet_fields(buffer);
    return 0;
}

#pragma pack(1) or __attribute__((packed)) needed additionally

 

 

 

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Input

165 1 52 18 119 90

Expected Output

Start: 165 Command: 1 Data: 4660 CRC: 119 End: 90