// Copyright 2023 Dolthub, Inc.
//
// 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.

// Copyright 2015 The Cockroach Authors.
//
// Use of this software is governed by the Business Source License
// included in the file licenses/BSL.txt.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0, included in the file
// licenses/APL.txt.

//go:build 386 || amd64
// +build 386 amd64

package encoding

import "unsafe"

// The idea for the fast ones complement is borrowed from fastXORBytes
// in the crypto standard library.
const wordSize = int(unsafe.Sizeof(uintptr(0)))

func onesComplement(b []byte) {
	n := len(b)
	w := n / wordSize
	if w > 0 {
		bw := *(*[]uintptr)(unsafe.Pointer(&b))
		for i := 0; i < w; i++ {
			bw[i] = ^bw[i]
		}
	}

	for i := w * wordSize; i < n; i++ {
		b[i] = ^b[i]
	}
}