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

int main(int argc, char *argv[]) {
  union pixel {
    struct c {
      unsigned r : 5;
      unsigned g : 6;
      unsigned b : 5;
    } c;
    uint16_t val;
  };

  union pixel p = {.c.r = 0x1b, .c.g = 0x4, .c.b = 0xa};
  printf("%.4" PRIx16 " == %" PRIx16 "\n", p.val, 0x1b | 0x4 << 5 | 0xa << 11);
}