Initial commit

ui/commands/integer.js

@@ -0,0 +1,90 @@
+// Sshwifty - A Web SSH client
+//
+// Copyright (C) 2019 Rui NI <nirui@gmx.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import Exception from "./exception.js";
+import * as reader from "../stream/reader.js";
+
+export const MAX = 0x3fff;
+export const MAX_BYTES = 2;
+
+const integerHasNextBit = 0x80;
+const integerValueCutter = 0x7f;
+
+export class Integer {
+  /**
+   * constructor
+   *
+   * @param {number} num Integer number
+   *
+   */
+  constructor(num) {
+    this.num = num;
+  }
+
+  /**
+   * Marshal integer to buffer
+   *
+   * @returns {Uint8Array} Integer buffer
+   *
+   * @throws {Exception} When number is too large
+   *
+   */
+  marshal() {
+    if (this.num > MAX) {
+      throw new Exception("Integer number cannot be greater than 0x3fff");
+    }
+
+    if (this.num <= integerValueCutter) {
+      return new Uint8Array([this.num & integerValueCutter]);
+    }
+
+    return new Uint8Array([
+      (this.num >> 7) | integerHasNextBit,
+      this.num & integerValueCutter
+    ]);
+  }
+
+  /**
+   * Parse the reader to build an Integer
+   *
+   * @param {reader.Reader} rd Data reader
+   *
+   */
+  async unmarshal(rd) {
+    for (let i = 0; i < MAX_BYTES; i++) {
+      let r = await reader.readOne(rd);
+
+      this.num |= r[0] & integerValueCutter;
+
+      if ((integerHasNextBit & r[0]) == 0) {
+        return;
+      }
+
+      this.num <<= 7;
+    }
+  }
+
+  /**
+   * Return the value of the number
+   *
+   * @returns {number} The integer value
+   *
+   */
+  value() {
+    return this.num;
+  }
+}