Added software spi stuff

lib/Bus/BusInterface.php

@@ -0,0 +1,42 @@
+<?php
+
+/*
+ * Copyright (C) 2014, NoccyLabs
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU 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 General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+namespace NoccyLabs\Gpio\Bus;
+
+interface BusInterface
+{
+    /**
+     * Write data to the bus. The data will be written immediately.
+     *
+     */
+    public function write($data);
+    
+    /**
+     * Read data from the buffer, or perform additional null reads over the 
+     * (SPI) bus to acquire the data.
+     *
+     */
+    public function read($bytes);
+    
+    /**
+     * Return the number of bytes in the read buffer
+     *
+     */
+    public function getBufferFill();
+}