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) {
    for (int i = 0; i < len; i++) {

        // Step 1: Clear bit at (pos + i)
        reg &= ~(1u << (pos + i));

        // Step 2: Extract i-th bit from val
        uint32_t bit = (val >> i) & 1u;

        // Step 3: Insert that bit into reg
        reg |= (bit << (pos + i));
    }

    return reg;
}

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;
}