18. Set Multiple Bits in 8-bit Register

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

uint8_t set_range(uint8_t reg, uint8_t start, uint8_t end) 
{
    uint8_t numBits = end - start + 1;
    uint8_t setBitMask = ((1 << numBits) - 1) << start;
    reg |= setBitMask;
    return reg;
}

int main() 
{
    uint8_t reg, start, end;
    scanf("%hhu %hhu %hhu", &reg, &start, &end);
    printf("%u", set_range(reg, start, end));
    return 0;
}