Restructured src files into a more logical hierarchy

src/core/operations/Checksum.js

@@ -0,0 +1,193 @@
+var Utils = require("../Utils.js");
+
+
+/**
+ * Checksum operations.
+ *
+ * @author n1474335 [n1474335@gmail.com]
+ * @copyright Crown Copyright 2016
+ * @license Apache-2.0
+ *
+ * @namespace
+ */
+var Checksum = module.exports = {
+
+    /**
+     * Fletcher-8 Checksum operation.
+     *
+     * @param {byteArray} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    runFletcher8: function(input, args) {
+        var a = 0,
+            b = 0;
+
+        for (var i = 0; i < input.length; i++) {
+            a = (a + input[i]) % 0xf;
+            b = (b + a) % 0xf;
+        }
+
+        return Utils.hex(((b << 4) | a) >>> 0, 2);
+    },
+
+
+    /**
+     * Fletcher-16 Checksum operation.
+     *
+     * @param {byteArray} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    runFletcher16: function(input, args) {
+        var a = 0,
+            b = 0;
+
+        for (var i = 0; i < input.length; i++) {
+            a = (a + input[i]) % 0xff;
+            b = (b + a) % 0xff;
+        }
+
+        return Utils.hex(((b << 8) | a) >>> 0, 4);
+    },
+
+
+    /**
+     * Fletcher-32 Checksum operation.
+     *
+     * @param {byteArray} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    runFletcher32: function(input, args) {
+        var a = 0,
+            b = 0;
+
+        for (var i = 0; i < input.length; i++) {
+            a = (a + input[i]) % 0xffff;
+            b = (b + a) % 0xffff;
+        }
+
+        return Utils.hex(((b << 16) | a) >>> 0, 8);
+    },
+
+
+    /**
+     * Fletcher-64 Checksum operation.
+     *
+     * @param {byteArray} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    runFletcher64: function(input, args) {
+        var a = 0,
+            b = 0;
+
+        for (var i = 0; i < input.length; i++) {
+            a = (a + input[i]) % 0xffffffff;
+            b = (b + a) % 0xffffffff;
+        }
+
+        return Utils.hex(b >>> 0, 8) + Utils.hex(a >>> 0, 8);
+    },
+
+
+    /**
+     * Adler-32 Checksum operation.
+     *
+     * @param {byteArray} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    runAdler32: function(input, args) {
+        var MOD_ADLER = 65521,
+            a = 1,
+            b = 0;
+
+        for (var i = 0; i < input.length; i++) {
+            a += input[i];
+            b += a;
+        }
+
+        a %= MOD_ADLER;
+        b %= MOD_ADLER;
+
+        return Utils.hex(((b << 16) | a) >>> 0, 8);
+    },
+
+
+    /**
+     * CRC-32 Checksum operation.
+     *
+     * @param {byteArray} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    runCRC32: function(input, args) {
+        var crcTable = window.crcTable || (window.crcTable = Checksum._genCRCTable()),
+            crc = 0 ^ (-1);
+
+        for (var i = 0; i < input.length; i++) {
+            crc = (crc >>> 8) ^ crcTable[(crc ^ input[i]) & 0xff];
+        }
+
+        return Utils.hex((crc ^ (-1)) >>> 0);
+    },
+
+
+    /**
+     * TCP/IP Checksum operation.
+     *
+     * @author GCHQ Contributor [1]
+     * @param {byteArray} input
+     * @param {Object[]} args
+     * @returns {string}
+     *
+     * @example
+     * // returns '3f2c'
+     * Checksum.runTcpIp([0x45,0x00,0x00,0x87,0xa3,0x1b,0x40,0x00,0x40,0x06,
+     *                      0x00,0x00,0xac,0x11,0x00,0x04,0xac,0x11,0x00,0x03])
+     *
+     * // returns 'a249'
+     * Checksum.runTcpIp([0x45,0x00,0x01,0x11,0x3f,0x74,0x40,0x00,0x40,0x06,
+     *                      0x00,0x00,0xac,0x11,0x00,0x03,0xac,0x11,0x00,0x04])
+     */
+    runTCPIP: function(input, args) {
+        var csum = 0;
+
+        for (var i = 0; i < input.length; i++) {
+            if (i % 2 === 0) {
+                csum += (input[i] << 8);
+            } else {
+                csum += input[i];
+            }
+        }
+
+        csum = (csum >> 16) + (csum & 0xffff);
+
+        return Utils.hex(0xffff - csum);
+    },
+
+
+    /**
+     * Generates a CRC table for use with CRC checksums.
+     *
+     * @private
+     * @returns {array}
+     */
+    _genCRCTable: function() {
+        var c,
+            crcTable = [];
+
+        for (var n = 0; n < 256; n++) {
+            c = n;
+            for (var k = 0; k < 8; k++) {
+                c = ((c & 1) ? (0xEDB88320 ^ (c >>> 1)) : (c >>> 1));
+            }
+            crcTable[n] = c;
+        }
+
+        return crcTable;
+    },
+
+};