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#pma/js/big_ints.js

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+/* vim: set expandtab sw=4 ts=4 sts=4: */
+/**
+ * phpMyAdmin's BigInts library
+ */
+
+/**
+ * @var BigInts object to handle big integers (in string)
+ *      as JS can handle upto 53 bits of precision only.
+ */
+var BigInts = {
+
+    /**
+     * Compares two integer strings
+     *
+     * @param int1 the string representation of 1st integer
+     * @param int2 the string representation of 2nd integer
+     *
+     * @return int 0 if equal, < 0 if int1 < int2, else > 0
+     */
+    compare: function(int1, int2) {
+        // trim integers
+        int1 = int1.trim();
+        int2 = int2.trim();
+        // length of integer strings
+        var len1 = int1.length;
+        var len2 = int2.length;
+        // integer is -ve or not
+        var isNeg1 = (int1[0] === '-');
+        var isNeg2 = (int2[0] === '-');
+        // Sign of int1 != int2 then no actual comparison
+        // is needed we can return result directly
+        if (isNeg1 !== isNeg2) {
+            return (isNeg1 === true ? -1 : 1);
+        }
+        // replace - sign with 0
+        int1[0] = isNeg1 ? '0' : int1[0];
+        int2[0] = isNeg2 ? '0' : int2[0];
+        // pad integers with 0 to make them
+        // equal length
+        int1 = BigInts.lpad(int1, len2);
+        int2 = BigInts.lpad(int2, len1);
+        // Now they are good to compare as strings
+        if (int1 !== int2) {
+            return (int1 < int2 ? -1 : 1);
+        }
+        return 0;
+    },
+
+    /**
+     * Adds leading zeros to a integer given a total length
+     *
+     * @param int   the string representation of the integer
+     * @param total the total length required
+     *
+     * @return int the integer of length given with added leading
+     *             zeros if necessary
+     */
+    lpad: function(int, total){
+        var len = int.length;
+        var pad = '';
+        while(len < total) {
+            pad += '0';
+            len++;
+        }
+        return (pad + int);
+    }
+};