// Print bits of a 32-bit integer
fun printBits(x: UInt, label: String) {
// Convert to binary and pad to 32 bits
val bits = x.toString(2).padStart(32, '0')
println("$label: $bits")
}
// Clear bits in range [l, r] inclusive (0 = least significant bit)
fun clearBits(x: UInt, l: Int, r: Int): UInt {
if (l < 0 || r > 31 || l > r) {
throw IllegalArgumentException("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
val maskLeft: UInt = (UInt.MAX_VALUE shl (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
val maskRight: UInt = ((1u shl l) - 1u)
printBits(maskRight, "maskRight")
// Combine both masks:
// maskLeft keeps bits above r.
// maskRight keeps bits below l.
// The range [l, r] becomes 0s.
val mask: UInt = maskLeft or maskRight
printBits(mask, "mask ")
return x and mask
}
fun main() {
val value: UInt = 0b11111100111111001111110011111100u
val l = 3 // start bit
val r = 10 // end bit
val result = clearBits(value, l, r)
printBits(value, "Before ")
printBits(result, "After ")
}
/*
run:
maskLeft : 11111111111111111111100000000000
maskRight: 00000000000000000000000000000111
mask : 11111111111111111111100000000111
Before : 11111100111111001111110011111100
After : 11111100111111001111100000000100
*/
