19. Extract a Bit Field from a 32-bit Register

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

unsigned int extractBitField(uint32_t reg, int pos, int len) {
    unsigned int mask = (1U << len) - 1;
    return (reg >> pos) & mask;
}

int main() {
    uint32_t reg;
    int pos, len;

    // Input: 32-bit reg, position, length
    scanf("%u %d %d", &reg, &pos, &len);

    // Output the extracted bit field
    printf("%u\n", extractBitField(reg, pos, len));

    return 0;
}

Right Shift reg by pos bits
 This moves the desired bit field to the least significant bits.
reg >> pos

Mask only the lower len bits using:
mask = (1U << len) - 1

Bitwise AND the shifted value with the mask:
result = (reg >> pos) & mask;