Implemented the tick handler

README.md

@@ -40,4 +40,38 @@ be portable/supported/efficient/a good idea):
     
     // The interrupts will now be polled approx every 5th php vm "tick"
 
+## Devices
 
+    $lcd = new NoccyLabs\Gpio\Device\Display\Pcd8544Device;
+    // Set I/O pins
+    $lcd->res = $gpio[4];
+    $lcd->dc  = $gpio[8];
+    ...
+    // Activate the device
+    $lcd->activate();
+    // Clear and draw text
+    $lcd->clear();
+    $lcd->writeAt(0,0,"Hello World");
+    echo $lcd->getRows(); // 5
+    echo $lcd->getCols(); // 19
+
+### LCD Bridge
+
+The LCD bridge will be able to bridge any device class implementing `LcdDeviceInterface`
+to stdin or a named pipe. This basically creates a user-space daemon to interface with
+the display without having to fiddle with bits.
+
+    $ lcdbridge -t pcd8544 --stdin
+    CLR
+    LOC 0 0
+    FONT 0
+    OUT Hello World
+    ^C
+    $ 
+
+Commands should include:
+
+ * `CLR` clears the display (`LcdDeviceInterface#clear()`)
+ * `LOC n m` moves the cursor to line n column m (0-indexed) (`LcdDeviceInterface#setCursorPos(n,m)`) 
+ * `FONT n` loads the default font (0) or a custom font file (`LcdDeviceInterface#setFont()`)
+ * `OUT` Write text to the display (`LcdDeviceInterface#write()`)

examples/tickhandler.php

@@ -0,0 +1,23 @@
+<?php
+
+require_once __DIR__."/../vendor/autoload.php";
+
+/*
+ * This example demonstrate a possibility, but not a best practice. When using
+ * the tick handler, make sure the code being executed has ticks declared.
+ *
+ */
+
+use NoccyLabs\Gpio\Gpio;
+use NoccyLabs\Gpio\GpioTickHandler;
+
+$gpio = new Gpio(true);
+
+$gpiotick = new GpioTickHandler();
+$gpiotick->registerGpio($gpio);
+
+declare(ticks=5);
+
+while(true) {
+    usleep(10000);
+}

lib/Gpio.php

@@ -57,11 +57,13 @@ class Gpio implements \ArrayAccess
         $read = $this->fd_gpio;
         $write = array();
         $except = $read;
-        select($read, $write, $except, 0);
-        foreach($except as $fd) {
-            $pin = $this->getPinFromFd($fd);
-            $pin->doInterrupt();
+        if (count($read)>0) {
+            stream_select($read, $write, $except, 0);
+            foreach($except as $fd) {
+                $pin = $this->getPinFromFd($fd);
+                $pin->doInterrupt();
             
+            }
         }
     }
     

lib/GpioTickHandler.php

@@ -0,0 +1,46 @@
+<?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;
+
+declare(ticks=5);
+
+class GpioTickHandler
+{
+    protected $gpio = array();
+
+    public function __construct()
+    {
+        register_tick_function(array($this,"onTick"));
+    }
+
+    public function registerGpio(Gpio $gpio)
+    {
+        $this->gpio[] = $gpio;
+        return $this;
+    }
+
+    public function onTick()
+    {
+        foreach($this->gpio as $g) {
+            $g->refresh();
+        }
+    }
+
+}