// Copyright 2020 Adam Lavrik <lavrik.adam@gmail.com>

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at

//  http://www.apache.org/licenses/LICENSE-2.0

// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on
// an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
// either express or implied. See the License for the specific
// language governing permissions and limitations under the License.

package i64

import "github.com/adam-lavrik/go-imath/ux"

// Pow raises `base` to `exponent` power.
// Fast binary algorithm is used.
// Pow(0, 0) == 1
func Pow(base int64, exponent uint) int64 {
	power := int64(1)
	for exponent > 0 {
		if ux.IsOdd(exponent) {
			power *= base
		}
		base *= base
		exponent >>= 1 // `exponent` fast division by 2
	}
	return power
}
