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// SPDX-License-Identifier: MIT
//
// Copyright (c) 2026 Khashayar Fereidani
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//! IPv4 header checksum calculation.
//!
//! This crate provides a highly optimized, `no_std` compatible implementation
//! of the Internet checksum defined in [RFC 1071](https://tools.ietf.org/html/rfc1071)
//! and used in IPv4, TCP, UDP, and ICMP headers.
//!
//! # Examples
//!
//! One-shot computation:
//!
//! ```
//! let data = [0x45, 0x00, 0x00, 0x30, 0x00, 0x00, 0x40, 0x00,
//! 0x40, 0x01, 0x00, 0x00, 0x0a, 0x00, 0x00, 0x01,
//! 0x0a, 0x00, 0x00, 0x02];
//!
//! let csum = ip4sum::checksum(&data);
//! ```
//!
//! Incremental computation with [`Checksum`]:
//!
//! ```
//! use ip4sum::Checksum;
//!
//! let mut hasher = Checksum::new();
//! hasher.update(&[0x45, 0x00, 0x00, 0x30, 0x00, 0x00, 0x40, 0x00,
//! 0x40, 0x01]);
//! hasher.update(&[0x00, 0x00]); // checksum field placeholder
//! hasher.update(&[0x0a, 0x00, 0x00, 0x01, 0x0a, 0x00, 0x00, 0x02]);
//! let csum = hasher.finalize();
//! ```
pub use Checksum;
/// Compute the Internet checksum of a byte slice.
///
/// Returns the one's-complement checksum in network byte order.
/// The checksum field in the input data should be set to zero
/// before calling this function.
///
/// For incremental computation, use [`Checksum`] instead.