25. Pack Multiple Fields into a 16-bit Control Register

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

uint16_t pack_register(uint8_t mode, uint8_t speed, uint8_t status) {
    if(mode > 7)
        mode = 7;
    if(speed > 0x1F)
        speed = 0x1F;
    if(status > 0x3F)
        status = 0x3F;
        
    uint16_t lreg = 0x0;
    lreg |= (mode & 0x7);
    lreg |= ((speed & 0x1F) << 3);
    lreg |= ((status & 0x3F) << 10);
    return lreg;
}

int main() {
    uint8_t mode, speed, status;
    scanf("%hhu %hhu %hhu", &mode, &speed, &status);

    uint16_t reg = pack_register(mode, speed, status);
    printf("%u", reg);
    return 0;
}