21. Replace Bit Field in a 32-bit Register

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

//for(int i=pos;i<pos+len;i++)
uint32_t replace_field(uint32_t reg, uint32_t val, uint8_t pos, uint8_t len) {
    uint32_t mask=0b0;
    uint32_t tmp;
    tmp=((1<<len)-1)<<pos;
    reg&=~tmp;
    return reg | (val<<pos);
}

int main() {
    uint32_t reg, val;
    uint8_t pos, len;
    scanf("%u %u %hhu %hhu", &reg, &val, &pos, &len);
    printf("%u", replace_field(reg, val, pos, len));
    return 0;
}