// SPDX-License-Identifier: BUSL-1.1
//
// Copyright (C) 2025, Berachain Foundation. All rights reserved.
// Use of this software is governed by the Business Source License included
// in the LICENSE file of this repository and at www.mariadb.com/bsl11.
//
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package pow

// PrevPowerOfTwo returns the previous power of 2 for the given input.
//
//nolint:mnd // todo fix.
func PrevPowerOfTwo[U64T ~uint64](u U64T) U64T {
	if u <= 1 {
		return 1
	}
	u |= u >> 1
	u |= u >> 2
	u |= u >> 4
	u |= u >> 8
	u |= u >> 16
	u |= u >> 32
	return u - (u >> 1)
}

// NextPowerOfTwo returns the next power of 2 for the given input.
//
//nolint:mnd // todo fix.
func NextPowerOfTwo[U64T ~uint64](u U64T) U64T {
	if u <= 1 {
		return 1
	}
	if u > 1<<63 {
		panic("Next power of 2 is 1 << 64.")
	}
	u--
	u |= u >> 1
	u |= u >> 2
	u |= u >> 4
	u |= u >> 8
	u |= u >> 16
	u |= u >> 32
	u++
	return u
}
