/*
 * Copyright (C)2005-2017 Haxe Foundation
 *
 * 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.
 */
package haxe.crypto;

/**
    Calculates the Crc32 of the given Bytes.
*/
class Crc32 {

	var crc : Int;

	public function new() {
		crc = 0xFFFFFFFF;
	}

	public function byte( b : Int ) {
		var tmp = (crc ^ b) & 0xFF;
		for( j in 0...8 ) {
			if( tmp & 1 == 1 )
				tmp = (tmp >>> 1) ^ 0xEDB88320;
			else
				tmp >>>= 1;
		}
		crc = (crc >>> 8) ^ tmp;
	}

	public function update( b : haxe.io.Bytes, pos, len ) {
		var b = b.getData();
		for( i in pos...pos+len ) {
			var tmp = (crc ^ haxe.io.Bytes.fastGet(b,i)) & 0xFF;
			for( j in 0...8 ) {
				if( tmp & 1 == 1 )
					tmp = (tmp >>> 1) ^ 0xEDB88320;
				else
					tmp >>>= 1;
			}
			crc = (crc >>> 8) ^ tmp;
		}
	}

	public function get() {
		return crc ^ 0xFFFFFFFF;
	}

	/**
		Calculates the CRC32 of the given data bytes
	**/
	public static function make( data : haxe.io.Bytes ) : Int {
		var init = 0xFFFFFFFF;
		var crc = init;
		var b = data.getData();
		for( i in 0...data.length ) {
			var tmp = (crc ^ haxe.io.Bytes.fastGet(b,i)) & 0xFF;
			for( j in 0...8 ) {
				if( tmp & 1 == 1 )
					tmp = (tmp >>> 1) ^ 0xEDB88320;
				else
					tmp >>>= 1;
			}
			crc = (crc >>> 8) ^ tmp;
		}
		return crc ^ init;
	}

}
