21. Replace Bit Field in a 32-bit Register

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

uint32_t replace_field(uint32_t reg, uint32_t val, uint8_t pos, uint8_t len) {
    // Your code here
  // clear bit 
    // int mask = (1u  << len) - 1;
    // reg &= ~(mask << pos);
    // reg |= (( val & mask) << pos);
    // return reg;

    int mask = (1u << len ) -1; 
    reg &= ~(mask << pos);
    reg |= ( val & mask) << pos;
    return reg;

  // set bit 
}

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;
}