added bitmappedgpio class to map several gpio in one byte

examples/bitmap.php

@@ -0,0 +1,24 @@
+<?php
+
+require_once __DIR__."/../vendor/autoload.php";
+
+/*
+ * This example demonstrates mapping GpioPins to bit values and writing bits
+ * in parallel.
+ *
+ */
+
+use NoccyLabs\Gpio\Gpio;
+use NoccyLabs\Gpio\Util\BitmappedGpio;
+use NoccyLabs\Gpio\GpioMapper\WiringPiMapper;
+
+$gpio = new Gpio();
+$gpio->setMapper( new WiringPiMapper(2) );
+
+$par = new BitmappedGpio();
+for($n = 0; $n < 7; $n++) {
+    $par->setGpioPin($n,$gpio[$n]);
+}
+
+$par->write(0xFF);
+$par->write(0x00);

lib/Util/BitmappedGpio.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace NoccyLabs\Gpio\Util;
+
+use NoccyLabs\Gpio\GpioPin;
+
+class BitmappedGpio
+{
+    protected $gpio = array();
+
+    public function __construct()
+    {
+        $this->gpio = array_fill(0,7,null);
+    }
+    
+    public function setGpioPin($bit, GpioPin $gpiopin = null)
+    {
+        if (($bit >= 0) && ($bit <= 7)) {
+            $this->gpio[$bit] = $gpiopin;
+        } else {
+            throw new \Exception("bit must be 0-7");
+        }
+    }
+    
+    public function read()
+    {
+        $r = 0;
+        foreach($this->gpio as $bit=>$gpio) {
+            if ($gpio->getValue()) { $r |= 1<<$bit; }
+        }
+        return $r;
+    }
+    
+    public function write($byte)
+    {
+        $r = 0;
+        foreach($this->gpio as $bit=>$gpio) {
+            if ($gpio) {
+                $gpio->setValue((bool)($byte & (1<<$bit)));
+            }
+        }
+        return $this;
+    }
+    
+    
+}