// Print bits of a 32-bit integer
fn print_bits(x: u32, label: &str) {
// Print as 32-bit binary with leading zeros
println!("{}: {:032b}", label, x);
}
// Clear bits in range [l, r] inclusive (0 = least significant bit)
fn clear_bits(x: u32, l: i32, r: i32) -> u32 {
if l < 0 || r > 31 || l > r {
panic!("Invalid bit range");
}
// maskLeft:
// Create a mask with 1s above bit r and 0s from bit r down to 0.
// Example: r = 5 → maskLeft = 11111111 11111111 11111111 11000000
let mask_left: u32 = (!0u32) << (r + 1);
print_bits(mask_left, "maskLeft ");
// maskRight:
// Create a mask with 1s below bit l and 0s from bit l upward.
// Example: l = 3 → maskRight = 00000000 00000000 00000000 00000111
let mask_right: u32 = (1u32 << l) - 1;
print_bits(mask_right, "maskRight");
// Combine both masks:
// maskLeft keeps bits above r.
// maskRight keeps bits below l.
// The range [l, r] becomes 0s.
let mask: u32 = mask_left | mask_right;
print_bits(mask, "mask ");
x & mask
}
fn main() {
let value: u32 = 0b11111100111111001111110011111100;
let l = 3; // start bit
let r = 10; // end bit
let result = clear_bits(value, l, r);
print_bits(value, "Before ");
print_bits(result, "After ");
}
/*
run:
maskLeft : 11111111111111111111100000000000
maskRight: 00000000000000000000000000000111
mask : 11111111111111111111100000000111
Before : 11111100111111001111110011111100
After : 11111100111111001111100000000100
*/
