Spin out driver subclass

Gemfile

@@ -1,4 +1,4 @@
 source 'https://rubygems.org'
 
 # Specify your gem's dependencies in pi_piper-sysfs.gemspec
-gemspec
+gemspec

lib/pi_piper/sysfs.rb

@@ -1,6 +1,7 @@
-require "pi_piper/sysfs/version"
-require "pi_piper/sysfs/sysfs"
+require 'pi_piper'
+require 'pi_piper/sysfs/version'
+require 'pi_piper/sysfs/driver'
 
 module PiPiper
-  self.driver= PiPiper::Sysfs
+  self.driver = PiPiper::Sysfs::Driver
 end

lib/pi_piper/sysfs/driver.rb

@@ -0,0 +1,110 @@
+module PiPiper
+  module Sysfs
+    class Driver < PiPiper::Driver
+
+      GPIO_HIGH = 1
+      GPIO_LOW  = 0
+
+      def initialize
+        @exported_pins = Set.new
+      end
+
+      def close
+        unexport_all
+        @exported_pins.empty? 
+      end
+
+  # Support GPIO pins
+      def pin_direction(pin, direction)
+        raise ArgumentError, "direction should be :in or :out" unless [:in, :out].include? direction
+        export(pin)
+        raise RuntimeError, "Pin #{pin} not exported" unless exported?(pin)
+        File.write(direction_file(pin), direction)
+      end
+
+      def pin_read(pin)
+        raise ArgumentError, "Pin #{pin} not exported" unless exported?(pin)
+        File.read(value_file(pin)).to_i
+      end
+
+      def pin_write(pin, value)
+        raise ArgumentError, "value should be GPIO_HIGH or GPIO_LOW" unless [GPIO_LOW, GPIO_HIGH].include? value
+        raise ArgumentError, "Pin #{pin} not exported" unless exported?(pin)
+        File.write(value_file(pin), value)
+      end
+
+      def pin_set_pud(pin, value)
+        raise NotImplementedError, "Pull up/down not available with this driver. keep it on :off" unless value == :off
+      end
+
+      def pin_set_trigger(pin, trigger)
+        raise ArgumentError, "trigger should be :falling, :rising, :both or :none" unless [:falling, :rising, :both, :none].include? trigger
+        raise ArgumentError, "Pin #{pin} not exported" unless exported?(pin)
+        File.write(edge_file(pin), trigger)
+      end
+
+      def pin_wait_for(pin, trigger)
+        pin_set_trigger(pin, trigger)
+        fd = File.open(value_file(pin), 'r')
+        value = nil
+
+        loop do
+          fd.read
+          IO.select(nil, nil, [fd], nil)
+          last_value = value
+          value = self.pin_read(pin)
+          if last_value != value
+            next if trigger == :rising and value == 0
+            next if trigger == :falling and value == 1
+            break
+          end
+        end
+
+      end
+
+  # Specific behaviours
+
+      def unexport(pin)
+        File.write("/sys/class/gpio/unexport", pin)
+        @exported_pins.delete(pin)
+      end
+
+      def unexport_all
+        @exported_pins.dup.each { |pin| unexport(pin) }
+      end
+
+      def exported?(pin)
+        @exported_pins.include?(pin)
+      end
+
+      private
+
+      def export(pin)
+        raise RuntimeError, "pin #{pin} is already reserved by another Pin instance" if @exported_pins.include?(pin)
+        File.write("/sys/class/gpio/export", pin)
+        @exported_pins << pin
+      end
+
+      def value_file(pin)
+        "/sys/class/gpio/gpio#{pin}/value"
+      end
+
+      def edge_file(pin)
+        "/sys/class/gpio/gpio#{pin}/edge"
+      end
+
+      def direction_file(pin)
+        "/sys/class/gpio/gpio#{pin}/direction"
+      end
+
+      def pin_value_changed?(pin, trigger, value)
+        last_value = value
+        value = pin_read(pin)
+        return false if value == last_value
+        return false if trigger == :rising && value == 0
+        return false if trigger == :falling && value == 1
+        true
+      end
+    end
+  end
+end

lib/pi_piper/sysfs/version.rb

@@ -1,6 +1,6 @@
 module PiPiper
   class Driver; end
-  class Sysfs < Driver
-    VERSION = "0.1.0"
+  module Sysfs
+    VERSION = '0.1.0'
   end
 end

pi_piper-sysfs.gemspec

@@ -12,7 +12,7 @@ Gem::Specification.new do |spec|
   spec.summary       = %q{GPIO kernel driver library for the Raspberry Pi and PiPiper}
   spec.description   = 'GPIO kernel driver library for the Raspberry Pi and other' \
                        ' boards that use the chipset. Commonly used with the' \
-                       ' PiPiper ruby library. it implements Pin (with events)' \
+                       ' PiPiper ruby library. It implements Pin (with events),' \
                        ' it reads from sysfs, and needs root UID to work'
 
   spec.homepage      = "https://github.com/PiPiper/sysfs"