package main
import (
"fmt"
)
// Print bits of a 32-bit integer
func printBits(x uint32, label string) {
// Print as 32-bit binary with leading zeros
fmt.Printf("%s: %032b\n", label, x)
}
// Clear bits in range [l, r] inclusive (0 = least significant bit)
func clearBits(x uint32, l, r int) uint32 {
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
maskLeft := ^uint32(0) << (r + 1)
printBits(maskLeft, "maskLeft ")
// maskRight:
// Create a mask with 1s below bit l and 0s from bit l upward.
// Example: l = 3 → maskRight = 00000000 00000000 00000000 00000111
maskRight := (uint32(1) << l) - 1
printBits(maskRight, "maskRight")
// Combine both masks:
// maskLeft keeps bits above r.
// maskRight keeps bits below l.
// The range [l, r] becomes 0s.
mask := maskLeft | maskRight
printBits(mask, "mask ")
return x & mask
}
func main() {
value := uint32(0b11111100111111001111110011111100)
l := 3 // start bit
r := 10 // end bit
result := clearBits(value, l, r)
printBits(value, "Before ")
printBits(result, "After ")
}
/*
run:
maskLeft : 11111111111111111111100000000000
maskRight: 00000000000000000000000000000111
mask : 11111111111111111111100000000111
Before : 11111100111111001111110011111100
After : 11111100111111001111100000000100
*/
