From 90556d1ddd0c160de84a9c3682245663c488d1c9 Mon Sep 17 00:00:00 2001
From: Donald Linton <lintond@gmail.com>
Date: Wed, 8 Jan 2020 07:02:36 -0500
Subject: [PATCH 1/4] put library in development mode to allow example editing

---
 .development | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 .development

diff --git a/.development b/.development
new file mode 100644
index 0000000..792d600
--- /dev/null
+++ b/.development
@@ -0,0 +1 @@
+#

From 424425514b98a472bca9cea9b55000f937f59a1d Mon Sep 17 00:00:00 2001
From: Donald Linton <lintond@gmail.com>
Date: Wed, 8 Jan 2020 16:54:46 -0500
Subject: [PATCH 2/4] Add virtual wrapper classes

---
 examples/Benchmark/Benchmark.ino   |   4 +-
 examples/BenchmarkI/BenchmarkI.ino | 316 +++++++++++++++++++++++++++++
 examples/BenchmarkV/BenchmarkV.ino | 205 +++++++++++++++++++
 src/Hardware/AVR/GPIO.h            |  10 +
 src/Hardware/SAM/GPIO.h            |   8 +
 src/IGPIO.h                        | 154 ++++++++++++++
 6 files changed, 696 insertions(+), 1 deletion(-)
 create mode 100644 examples/BenchmarkI/BenchmarkI.ino
 create mode 100644 examples/BenchmarkV/BenchmarkV.ino
 create mode 100644 src/IGPIO.h

diff --git a/examples/Benchmark/Benchmark.ino b/examples/Benchmark/Benchmark.ino
index db2679a..8b9e14b 100644
--- a/examples/Benchmark/Benchmark.ino
+++ b/examples/Benchmark/Benchmark.ino
@@ -1,6 +1,7 @@
-#include "GPIO.h"
+#include "IGPIO.h"
 #include "benchmark.h"
 
+
 GPIO<BOARD::D12> button;
 GPIO<BOARD::D13> led;
 #define BUTTON_PIN 12
@@ -163,4 +164,5 @@ void loop()
 
   Serial.println();
   delay(2000);
+  while(true) ;
 }
diff --git a/examples/BenchmarkI/BenchmarkI.ino b/examples/BenchmarkI/BenchmarkI.ino
new file mode 100644
index 0000000..ed848d4
--- /dev/null
+++ b/examples/BenchmarkI/BenchmarkI.ino
@@ -0,0 +1,316 @@
+#include "GPIO.h"
+#include "benchmark.h"
+
+/* 
+ *  NANO GPIO
+16:06:16.704 -> 1.1 Arduino core digitalRead: 3.836
+16:06:16.704 -> 1.2 Arduino core digitalWrite(HIGH): 4.216
+16:06:16.704 -> 1.3 Arduino core digitalWrite(LOW): 4.088
+16:06:16.739 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 8.236
+16:06:16.739 -> 1.5 Arduino core toggle; digitalWrite: 8.304
+16:06:16.774 -> 2.1 GPIO pin value operator: 0.064
+16:06:16.774 -> 2.2 GPIO high member function: 0.128
+16:06:16.774 -> 2.3 GPIO low member function: 0.132
+16:06:16.774 -> 2.4 GPIO assignment HIGH: 0.132
+16:06:16.774 -> 2.5 GPIO assignment LOW: 0.132
+16:06:16.807 -> 2.6 GPIO toggle; value and assignment operator: 0.344
+16:06:16.807 -> 2.7 GPIO toggle; high and low member functions: 0.248
+16:06:16.807 -> 2.8 GPIO toggle; assignment operator, HIGH/LOW: 0.248
+16:06:16.807 -> 2.9 GPIO toggle member function: 0.124
+16:06:16.843 ->
+  
+  NANO VGPIO
+16:10:40.288 -> 1.1 Arduino core digitalRead: 3.836
+16:10:40.288 -> 1.2 Arduino core digitalWrite(HIGH): 4.216
+16:10:40.321 -> 1.3 Arduino core digitalWrite(LOW): 4.084
+16:10:40.321 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 8.236
+16:10:40.321 -> 1.5 Arduino core toggle; digitalWrite: 8.304
+16:10:40.356 -> 2.1 VGPIO pin value operator: 0.064
+16:10:40.356 -> 2.2 VGPIO high member function: 0.756
+16:10:40.356 -> 2.3 VGPIO low member function: 0.756
+16:10:40.390 -> 2.4 VGPIO assignment HIGH: 0.132
+16:10:40.390 -> 2.5 VGPIO assignment LOW: 0.132
+16:10:40.390 -> 2.6 VGPIO toggle; value and assignment operator: 1.356
+16:10:40.390 -> 2.7 VGPIO toggle; high and low member functions: 1.512
+16:10:40.424 -> 2.8 VGPIO toggle; assignment operator, HIGH/LOW: 0.256
+16:10:40.424 -> 2.9 VGPIO toggle member function: 0.756
+16:10:40.424 -> 
+
+   NANO IGPIO
+16:20:32.106 -> 1.1 Arduino core digitalRead: 3.840
+16:20:32.106 -> 1.2 Arduino core digitalWrite(HIGH): 4.216
+16:20:32.140 -> 1.3 Arduino core digitalWrite(LOW): 4.084
+16:20:32.140 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 8.236
+16:20:32.175 -> 1.5 Arduino core toggle; digitalWrite: 8.304
+16:20:32.175 -> 2.1 IGPIO pin value operator: 1.512
+16:20:32.175 -> 2.2 IGPIO high member function: 1.448
+16:20:32.212 -> 2.3 IGPIO low member function: 1.452
+16:20:32.212 -> 2.4 IGPIO assignment HIGH: 1.700
+16:20:32.212 -> 2.5 IGPIO assignment LOW: 1.764
+16:20:32.212 -> 2.6 IGPIO toggle; value and assignment operator: 2.924
+16:20:32.246 -> 2.7 IGPIO toggle; high and low member functions: 2.896
+16:20:32.246 -> 2.8 IGPIO toggle; assignment operator, HIGH/LOW: 3.460
+16:20:32.246 -> 2.9 IGPIO toggle member function: 1.444
+16:20:32.281 -> 
+
+  MEGA GPIO
+16:26:50.265 -> 1.1 Arduino core digitalRead: 6.412
+16:26:50.299 -> 1.2 Arduino core digitalWrite(HIGH): 6.916
+16:26:50.299 -> 1.3 Arduino core digitalWrite(LOW): 6.792
+16:26:50.332 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 13.204
+16:26:50.366 -> 1.5 Arduino core toggle; digitalWrite: 13.712
+16:26:50.366 -> 2.1 GPIO pin value operator: 0.064
+16:26:50.366 -> 2.2 GPIO high member function: 0.124
+16:26:50.366 -> 2.3 GPIO low member function: 0.124
+16:26:50.401 -> 2.4 GPIO assignment HIGH: 0.124
+16:26:50.401 -> 2.5 GPIO assignment LOW: 0.128
+16:26:50.401 -> 2.6 GPIO toggle; value and assignment operator: 0.352
+16:26:50.401 -> 2.7 GPIO toggle; high and low member functions: 0.256
+16:26:50.434 -> 2.8 GPIO toggle; assignment operator, HIGH/LOW: 0.248
+16:26:50.434 -> 2.9 GPIO toggle member function: 0.132
+16:26:50.434 -> 3.1 Arduino core digitalRead: 6.284
+16:26:50.468 -> 3.2 Arduino core digitalWrite(HIGH): 7.168
+16:26:50.468 -> 3.3 Arduino core digitalWrite(LOW): 7.048
+16:26:50.468 -> 3.4 Arduino core toggle; digitalRead-digitalWrite: 13.652
+16:26:50.502 -> 3.5 Arduino core toggle; digitalWrite: 14.208
+16:26:50.536 -> 4.1 GPIO pin value operator: 0.128
+16:26:50.536 -> 4.2 GPIO high member function: 0.504
+16:26:50.536 -> 4.3 GPIO low member function: 0.504
+16:26:50.536 -> 4.4 GPIO assignment HIGH: 0.508
+16:26:50.571 -> 4.5 GPIO assignment LOW: 0.504
+16:26:50.571 -> 4.6 GPIO toggle; value and assignment operator: 0.944
+16:26:50.571 -> 4.7 GPIO toggle; high and low member functions: 1.008
+16:26:50.571 -> 4.8 GPIO toggle; assignment operator: 1.012
+16:26:50.606 -> 4.9 GPIO toggle member function: 0.500
+16:26:50.606 -> 
+  
+  MEGA VGPIO
+16:26:20.659 -> 1.1 Arduino core digitalRead: 6.412
+16:26:20.659 -> 1.2 Arduino core digitalWrite(HIGH): 6.920
+16:26:20.693 -> 1.3 Arduino core digitalWrite(LOW): 6.796
+16:26:20.693 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 13.204
+16:26:20.728 -> 1.5 Arduino core toggle; digitalWrite: 13.712
+16:26:20.761 -> 2.1 VGPIO pin value operator: 0.068
+16:26:20.761 -> 2.2 VGPIO high member function: 0.820
+16:26:20.761 -> 2.3 VGPIO low member function: 0.820
+16:26:20.761 -> 2.4 VGPIO assignment HIGH: 0.124
+16:26:20.761 -> 2.5 VGPIO assignment LOW: 0.124
+16:26:20.795 -> 2.6 VGPIO toggle; value and assignment operator: 1.660
+16:26:20.795 -> 2.7 VGPIO toggle; high and low member functions: 1.636
+16:26:20.795 -> 2.8 VGPIO toggle; assignment operator, HIGH/LOW: 0.256
+16:26:20.829 -> 2.9 VGPIO toggle member function: 0.820
+16:26:20.829 -> 3.1 Arduino core digitalRead: 6.356
+16:26:20.829 -> 3.2 Arduino core digitalWrite(HIGH): 7.232
+16:26:20.864 -> 3.3 Arduino core digitalWrite(LOW): 7.104
+16:26:20.864 -> 3.4 Arduino core toggle; digitalRead-digitalWrite: 13.768
+16:26:20.899 -> 3.5 Arduino core toggle; digitalWrite: 14.344
+16:26:20.899 -> 4.1 VGPIO pin value operator: 0.132
+16:26:20.932 -> 4.2 VGPIO high member function: 1.448
+16:26:20.932 -> 4.3 VGPIO low member function: 1.448
+16:26:20.932 -> 4.4 VGPIO assignment HIGH: 1.576
+16:26:20.932 -> 4.5 VGPIO assignment LOW: 1.764
+16:26:20.966 -> 4.6 VGPIO toggle; value and assignment operator: 2.072
+16:26:20.966 -> 4.7 VGPIO toggle; high and low member functions: 2.892
+16:26:20.966 -> 4.8 VGPIO toggle; assignment operator: 3.332
+16:26:21.000 -> 4.9 VGPIO toggle member function: 1.452
+16:26:21.000 -> 
+  
+
+  MEGA IGPIO
+16:24:12.181 -> 1.1 Arduino core digitalRead: 6.420
+16:24:12.181 -> 1.2 Arduino core digitalWrite(HIGH): 6.920
+16:24:12.181 -> 1.3 Arduino core digitalWrite(LOW): 6.792
+16:24:12.216 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 13.212
+16:24:12.251 -> 1.5 Arduino core toggle; digitalWrite: 13.704
+16:24:12.251 -> 2.1 IGPIO pin value operator: 1.700
+16:24:12.251 -> 2.2 IGPIO high member function: 1.572
+16:24:12.286 -> 2.3 IGPIO low member function: 1.572
+16:24:12.286 -> 2.4 IGPIO assignment HIGH: 1.828
+16:24:12.286 -> 2.5 IGPIO assignment LOW: 1.884
+16:24:12.286 -> 2.6 IGPIO toggle; value and assignment operator: 3.176
+16:24:12.319 -> 2.7 IGPIO toggle; high and low member functions: 3.152
+16:24:12.319 -> 2.8 IGPIO toggle; assignment operator, HIGH/LOW: 3.712
+16:24:12.352 -> 2.9 IGPIO toggle member function: 1.572
+16:24:12.352 -> 3.1 Arduino core digitalRead: 6.356
+16:24:12.352 -> 3.2 Arduino core digitalWrite(HIGH): 7.236
+16:24:12.386 -> 3.3 Arduino core digitalWrite(LOW): 7.108
+16:24:12.386 -> 3.4 Arduino core toggle; digitalRead-digitalWrite: 13.776
+16:24:12.421 -> 3.5 Arduino core toggle; digitalWrite: 14.336
+16:24:12.421 -> 4.1 IGPIO pin value operator: 1.140
+16:24:12.455 -> 4.2 IGPIO high member function: 1.452
+16:24:12.455 -> 4.3 IGPIO low member function: 1.444
+16:24:12.455 -> 4.4 IGPIO assignment HIGH: 1.576
+16:24:12.455 -> 4.5 IGPIO assignment LOW: 1.760
+16:24:12.488 -> 4.6 IGPIO toggle; value and assignment operator: 2.076
+16:24:12.488 -> 4.7 IGPIO toggle; high and low member functions: 2.896
+16:24:12.488 -> 4.8 IGPIO toggle; assignment operator: 3.328
+16:24:12.523 -> 4.9 IGPIO toggle member function: 1.452
+16:24:12.523 -> 
+  
+ */
+const IGPIO& button = VGPIO<BOARD::D12>();
+const IGPIO& led = VGPIO<BOARD::D13>();
+#define BUTTON_PIN 12
+#define LED_PIN 13
+
+void setup()
+{
+  Serial.begin(57600);
+  while (!Serial);
+  delay(1000);
+  
+  // Set pin mode; Arduino style
+  pinMode(LED_PIN, OUTPUT);
+  pinMode(BUTTON_PIN, INPUT_PULLUP);
+
+  // Set pin mode; GPIO style
+  led.output();
+  button.input();
+  button.pullup();
+
+  // Calculate baseline
+  BENCHMARK_BASELINE(1000);
+}
+
+void loop()
+{
+  BENCHMARK("1.1 Arduino core digitalRead", 1000) {
+    bool state = digitalRead(BUTTON_PIN);
+    (void) state;
+  }
+
+  BENCHMARK("1.2 Arduino core digitalWrite(HIGH)", 1000) {
+    digitalWrite(LED_PIN, HIGH);
+  }
+
+  BENCHMARK("1.3 Arduino core digitalWrite(LOW)", 1000) {
+    digitalWrite(LED_PIN, LOW);
+  }
+
+  BENCHMARK("1.4 Arduino core toggle; digitalRead-digitalWrite", 1000) {
+    digitalWrite(LED_PIN, !digitalRead(LED_PIN));
+  }
+
+  BENCHMARK("1.5 Arduino core toggle; digitalWrite", 1000) {
+    digitalWrite(LED_PIN, HIGH);
+    digitalWrite(LED_PIN, LOW);
+  }
+
+  BENCHMARK("2.1 IGPIO pin value operator", 1000) {
+    bool state = button;
+    (void) state;
+  }
+
+  BENCHMARK("2.2 IGPIO high member function", 1000) {
+    led.high();
+  }
+
+  BENCHMARK("2.3 IGPIO low member function", 1000) {
+    led.low();
+  }
+
+  BENCHMARK("2.4 IGPIO assignment HIGH", 1000) {
+    led = HIGH;
+  }
+
+  BENCHMARK("2.5 IGPIO assignment LOW", 1000) {
+    led = LOW;
+  }
+
+  BENCHMARK("2.6 IGPIO toggle; value and assignment operator", 1000) {
+    led.write( !led.read() );
+  }
+
+  BENCHMARK("2.7 IGPIO toggle; high and low member functions", 1000) {
+    led.high();
+    led.low();
+  }
+
+  BENCHMARK("2.8 IGPIO toggle; assignment operator, HIGH/LOW", 1000) {
+    led = HIGH;
+    led = LOW;
+  }
+
+  BENCHMARK("2.9 IGPIO toggle member function", 1000) {
+    led.toggle();
+  }
+
+#ifdef PORTH
+
+  // IGPIO atomic access of io ports with higher address. These
+  // benchmarks are for Arduino Mega pins that use ports above address
+  // 0x40 (PORTH, PORTJ, PINK and PINL). See Hardware/AVR/Board.h.
+
+#define DIN_PIN 6
+#define DOUT_PIN 7
+  const IGPIO& din = VGPIO<BOARD::D6>();
+  const IGPIO& dout = VGPIO<BOARD::D7>();
+  din.input();
+  dout.input();
+
+  BENCHMARK("3.1 Arduino core digitalRead", 1000) {
+    bool state = digitalRead(DIN_PIN);
+    (void) state;
+  }
+
+  BENCHMARK("3.2 Arduino core digitalWrite(HIGH)", 1000) {
+    digitalWrite(DOUT_PIN, HIGH);
+  }
+
+  BENCHMARK("3.3 Arduino core digitalWrite(LOW)", 1000) {
+    digitalWrite(DOUT_PIN, LOW);
+  }
+
+  BENCHMARK("3.4 Arduino core toggle; digitalRead-digitalWrite", 1000) {
+    digitalWrite(DOUT_PIN, !digitalRead(DOUT_PIN));
+  }
+
+  BENCHMARK("3.5 Arduino core toggle; digitalWrite", 1000) {
+    digitalWrite(DOUT_PIN, HIGH);
+    digitalWrite(DOUT_PIN, LOW);
+  }
+
+  BENCHMARK("4.1 IGPIO pin value operator", 1000) {
+    bool state = din;
+    (void) state;
+  }
+
+  BENCHMARK("4.2 IGPIO high member function", 1000) {
+    dout.high();
+  }
+
+  BENCHMARK("4.3 IGPIO low member function", 1000) {
+    dout.low();
+  }
+
+  BENCHMARK("4.4 IGPIO assignment HIGH", 1000) {
+    dout = HIGH;
+  }
+
+  BENCHMARK("4.5 IGPIO assignment LOW", 1000) {
+    dout = LOW;
+  }
+
+  BENCHMARK("4.6 IGPIO toggle; value and assignment operator", 1000) {
+    dout.write( !dout.read() );
+  }
+
+  BENCHMARK("4.7 IGPIO toggle; high and low member functions", 1000) {
+    dout.high();
+    dout.low();
+  }
+
+  BENCHMARK("4.8 IGPIO toggle; assignment operator", 1000) {
+    dout = HIGH;
+    dout = LOW;
+  }
+
+  BENCHMARK("4.9 IGPIO toggle member function", 1000) {
+    dout.toggle();
+  }
+#endif
+
+  Serial.println();
+  delay(2000);
+  while(true) ;
+}
diff --git a/examples/BenchmarkV/BenchmarkV.ino b/examples/BenchmarkV/BenchmarkV.ino
new file mode 100644
index 0000000..e6acbe0
--- /dev/null
+++ b/examples/BenchmarkV/BenchmarkV.ino
@@ -0,0 +1,205 @@
+#include "GPIO.h"
+#include "benchmark.h"
+
+/* 
+ *  NANO GPIO
+16:06:16.704 -> 1.1 Arduino core digitalRead: 3.836
+16:06:16.704 -> 1.2 Arduino core digitalWrite(HIGH): 4.216
+16:06:16.704 -> 1.3 Arduino core digitalWrite(LOW): 4.088
+16:06:16.739 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 8.236
+16:06:16.739 -> 1.5 Arduino core toggle; digitalWrite: 8.304
+16:06:16.774 -> 2.1 GPIO pin value operator: 0.064
+16:06:16.774 -> 2.2 GPIO high member function: 0.128
+16:06:16.774 -> 2.3 GPIO low member function: 0.132
+16:06:16.774 -> 2.4 GPIO assignment HIGH: 0.132
+16:06:16.774 -> 2.5 GPIO assignment LOW: 0.132
+16:06:16.807 -> 2.6 GPIO toggle; value and assignment operator: 0.344
+16:06:16.807 -> 2.7 GPIO toggle; high and low member functions: 0.248
+16:06:16.807 -> 2.8 GPIO toggle; assignment operator, HIGH/LOW: 0.248
+16:06:16.807 -> 2.9 GPIO toggle member function: 0.124
+16:06:16.843 ->
+  
+  NANO VGPIO
+16:10:40.288 -> 1.1 Arduino core digitalRead: 3.836
+16:10:40.288 -> 1.2 Arduino core digitalWrite(HIGH): 4.216
+16:10:40.321 -> 1.3 Arduino core digitalWrite(LOW): 4.084
+16:10:40.321 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 8.236
+16:10:40.321 -> 1.5 Arduino core toggle; digitalWrite: 8.304
+16:10:40.356 -> 2.1 VGPIO pin value operator: 0.064
+16:10:40.356 -> 2.2 VGPIO high member function: 0.756
+16:10:40.356 -> 2.3 VGPIO low member function: 0.756
+16:10:40.390 -> 2.4 VGPIO assignment HIGH: 0.132
+16:10:40.390 -> 2.5 VGPIO assignment LOW: 0.132
+16:10:40.390 -> 2.6 VGPIO toggle; value and assignment operator: 1.356
+16:10:40.390 -> 2.7 VGPIO toggle; high and low member functions: 1.512
+16:10:40.424 -> 2.8 VGPIO toggle; assignment operator, HIGH/LOW: 0.256
+16:10:40.424 -> 2.9 VGPIO toggle member function: 0.756
+16:10:40.424 -> 
+
+
+ */
+VGPIO<BOARD::D12> button;
+VGPIO<BOARD::D13> led;
+#define BUTTON_PIN 12
+#define LED_PIN 13
+
+void setup()
+{
+  Serial.begin(57600);
+  while (!Serial);
+
+  // Set pin mode; Arduino style
+  pinMode(LED_PIN, OUTPUT);
+  pinMode(BUTTON_PIN, INPUT_PULLUP);
+
+  // Set pin mode; GPIO style
+  led.output();
+  button.input();
+  button.pullup();
+
+  // Calculate baseline
+  BENCHMARK_BASELINE(1000);
+}
+
+void loop()
+{
+  BENCHMARK("1.1 Arduino core digitalRead", 1000) {
+    bool state = digitalRead(BUTTON_PIN);
+    (void) state;
+  }
+
+  BENCHMARK("1.2 Arduino core digitalWrite(HIGH)", 1000) {
+    digitalWrite(LED_PIN, HIGH);
+  }
+
+  BENCHMARK("1.3 Arduino core digitalWrite(LOW)", 1000) {
+    digitalWrite(LED_PIN, LOW);
+  }
+
+  BENCHMARK("1.4 Arduino core toggle; digitalRead-digitalWrite", 1000) {
+    digitalWrite(LED_PIN, !digitalRead(LED_PIN));
+  }
+
+  BENCHMARK("1.5 Arduino core toggle; digitalWrite", 1000) {
+    digitalWrite(LED_PIN, HIGH);
+    digitalWrite(LED_PIN, LOW);
+  }
+
+  BENCHMARK("2.1 VGPIO pin value operator", 1000) {
+    bool state = button;
+    (void) state;
+  }
+
+  BENCHMARK("2.2 VGPIO high member function", 1000) {
+    led.high();
+  }
+
+  BENCHMARK("2.3 VGPIO low member function", 1000) {
+    led.low();
+  }
+
+  BENCHMARK("2.4 VGPIO assignment HIGH", 1000) {
+    led = HIGH;
+  }
+
+  BENCHMARK("2.5 VGPIO assignment LOW", 1000) {
+    led = LOW;
+  }
+
+  BENCHMARK("2.6 VGPIO toggle; value and assignment operator", 1000) {
+    led = !led;
+  }
+
+  BENCHMARK("2.7 VGPIO toggle; high and low member functions", 1000) {
+    led.high();
+    led.low();
+  }
+
+  BENCHMARK("2.8 VGPIO toggle; assignment operator, HIGH/LOW", 1000) {
+    led = HIGH;
+    led = LOW;
+  }
+
+  BENCHMARK("2.9 VGPIO toggle member function", 1000) {
+    led.toggle();
+  }
+
+#ifdef PORTH
+
+  // VGPIO atomic access of io ports with higher address. These
+  // benchmarks are for Arduino Mega pins that use ports above address
+  // 0x40 (PORTH, PORTJ, PINK and PINL). See Hardware/AVR/Board.h.
+
+#define DIN_PIN 6
+#define DOUT_PIN 7
+  VGPIO<BOARD::D6> din;
+  VGPIO<BOARD::D7> dout;
+  din.input();
+  dout.input();
+
+  BENCHMARK("3.1 Arduino core digitalRead", 1000) {
+    bool state = digitalRead(DIN_PIN);
+    (void) state;
+  }
+
+  BENCHMARK("3.2 Arduino core digitalWrite(HIGH)", 1000) {
+    digitalWrite(DOUT_PIN, HIGH);
+  }
+
+  BENCHMARK("3.3 Arduino core digitalWrite(LOW)", 1000) {
+    digitalWrite(DOUT_PIN, LOW);
+  }
+
+  BENCHMARK("3.4 Arduino core toggle; digitalRead-digitalWrite", 1000) {
+    digitalWrite(DOUT_PIN, !digitalRead(DOUT_PIN));
+  }
+
+  BENCHMARK("3.5 Arduino core toggle; digitalWrite", 1000) {
+    digitalWrite(DOUT_PIN, HIGH);
+    digitalWrite(DOUT_PIN, LOW);
+  }
+
+  BENCHMARK("4.1 VGPIO pin value operator", 1000) {
+    bool state = din;
+    (void) state;
+  }
+
+  BENCHMARK("4.2 VGPIO high member function", 1000) {
+    dout.high();
+  }
+
+  BENCHMARK("4.3 VGPIO low member function", 1000) {
+    dout.low();
+  }
+
+  BENCHMARK("4.4 VGPIO assignment HIGH", 1000) {
+    dout = HIGH;
+  }
+
+  BENCHMARK("4.5 VGPIO assignment LOW", 1000) {
+    dout = LOW;
+  }
+
+  BENCHMARK("4.6 VGPIO toggle; value and assignment operator", 1000) {
+    dout = !dout;
+  }
+
+  BENCHMARK("4.7 VGPIO toggle; high and low member functions", 1000) {
+    dout.high();
+    dout.low();
+  }
+
+  BENCHMARK("4.8 VGPIO toggle; assignment operator", 1000) {
+    dout = HIGH;
+    dout = LOW;
+  }
+
+  BENCHMARK("4.9 VGPIO toggle member function", 1000) {
+    dout.toggle();
+  }
+#endif
+
+  Serial.println();
+  delay(2000);
+  while(true) ;
+}
diff --git a/src/Hardware/AVR/GPIO.h b/src/Hardware/AVR/GPIO.h
index b5dc299..08a4268 100644
--- a/src/Hardware/AVR/GPIO.h
+++ b/src/Hardware/AVR/GPIO.h
@@ -30,6 +30,14 @@
 template<BOARD::pin_t PIN>
 class GPIO {
 public:
+
+  /**
+   * Return the encapsulated pin
+   */
+  unsigned int pin() {
+    return (unsigned int) PIN;
+  }
+  
   /**
    * Set pin to input mode.
    */
@@ -190,4 +198,6 @@ class GPIO {
   /** Pin bit position mask in control registers. */
   static const uint8_t MASK = GPIO_MASK(PIN);
 };
+
+
 #endif
diff --git a/src/Hardware/SAM/GPIO.h b/src/Hardware/SAM/GPIO.h
index 7fd8795..a8e49e1 100644
--- a/src/Hardware/SAM/GPIO.h
+++ b/src/Hardware/SAM/GPIO.h
@@ -30,6 +30,13 @@
 template<BOARD::pin_t PIN>
 class GPIO {
 public:
+  /**
+   * Return the encapsulated pin
+   */
+  unsigned int pin() {
+    return (unsigned int) PIN;
+  }
+  
   /**
    * Construct pin instance and initiate.
    */
@@ -209,4 +216,5 @@ class GPIO {
     }
   }
 };
+
 #endif
diff --git a/src/IGPIO.h b/src/IGPIO.h
new file mode 100644
index 0000000..a19f048
--- /dev/null
+++ b/src/IGPIO.h
@@ -0,0 +1,154 @@
+/**
+ * @file GPIO.h
+ * @version 1.0
+ *
+ * @section License
+ * Copyright (C) 2017, Mikael Patel
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ */
+
+#ifndef IGPIO_H
+#define IGPIO_H
+
+#include <GPIO.h>
+
+/**
+ * A non-templated pure virtual interface base class for the processor-specific
+ * General Purpose Digital I/O pin template classes. Those classes areighly
+ * optimized pin access. The PIN address is a bit pointer to the port control
+ * register. See Hardware/AVR/Board.h for details.
+ * 
+ * This base class allows GPIO objects to be passed as parameters to other
+ * non-templated classes and functions.
+ */
+
+class IGPIO {
+   public:
+    /**
+     * Default constructor
+     */
+    IGPIO(){};
+
+    /**
+     * Virtual destructor
+     */
+    virtual ~IGPIO(){};
+
+    /**
+     * Test if another IGPIO object uses the same pin.
+     */
+    inline bool operator==(IGPIO &that) { return pin() == that.pin(); }
+
+    /**
+     * Get the assigned pin.
+     */
+    virtual unsigned int pin() = 0;
+
+    /**
+     * Set pin to input mode.
+     */
+    virtual void input() = 0;
+
+    /**
+     * Used with input() to activate internal pullup resistor on
+     * input pin.
+     */
+    virtual void pullup() = 0;
+
+    /**
+     * Set pin to output mode.
+     */
+    virtual void output() = 0;
+
+    /**
+     * Open-drain pin. Use input() for high and output() for low.
+     */
+    virtual void open_drain() = 0;
+
+    /**
+     * Return current pin state.
+     * @return state.
+     */
+    virtual bool read() = 0;
+
+    /**
+     * Return current pin state. Shorthand for read().
+     * @return state.
+     */
+    virtual operator bool() = 0;
+
+    /**
+     * Set pin low(0). Shorthand for write(LOW).
+     */
+    virtual void low() = 0;
+
+    /**
+     * Set pin high(1). Shorthand for write(HIGH).
+     */
+    virtual void high() = 0;
+
+    /**
+     * Toggle pin state. Shorthand for write(!read()).
+     */
+    virtual void toggle() = 0;
+
+    /**
+     * Set pin to given state. Non-zero value will set the pin HIGH(1),
+     * and zero value will set the pin LOW(0).
+     * @param[in] value to set pin.
+     */
+    virtual void write(int value) = 0;
+
+    /**
+     * Set pin to given state. Non-zero value will set the pin HIGH(1),
+     * and zero value will set the pin LOW(0). Shorthand for write(value).
+     * @param[in] value to set pin.
+     */
+    virtual void operator=(int value) = 0;
+
+    /**
+     * Generate pulse with given width in micro-seconds. Interrupts
+     * are disabled while generating the pulse.
+     * @param[in] width in micro-seconds.
+     */
+    virtual void pulse(uint16_t width) = 0;
+
+    /**
+     * Detect pulse and return width in micro-seconds.
+     * @return width in micro-seconds.
+     */
+    virtual int pulse() = 0;
+};
+
+
+template<BOARD::pin_t PIN>
+class VGPIO : public IGPIO, public GPIO<PIN> {
+  public:
+    inline bool operator==(IGPIO &that) { return pin() == that.pin(); }
+    unsigned int pin() { return GPIO<PIN>::pin(); }
+    void input() { GPIO<PIN>::input(); }
+    void pullup() { GPIO<PIN>::pullup(); }
+    void output() { GPIO<PIN>::output(); } 
+    void open_drain() { GPIO<PIN>::open_drain(); }
+    bool read() { return GPIO<PIN>::read(); }
+    operator bool() { return GPIO<PIN>::read(); }
+    void low() { GPIO<PIN>::low(); }
+    void high() { GPIO<PIN>::high(); }
+    void toggle() { GPIO<PIN>::toggle(); }
+    void write(int value)  { GPIO<PIN>::write(value); };
+    void operator=(int value)  { GPIO<PIN>::write(value); }
+    void pulse(uint16_t width) { GPIO<PIN>::pulse(width); }
+    int pulse() { return GPIO<PIN>::pulse(); }
+
+};
+
+#endif
\ No newline at end of file

From 06e0b759e251051ad2419d3629fc9929e106f7c5 Mon Sep 17 00:00:00 2001
From: Donald Linton <lintond@gmail.com>
Date: Thu, 16 Jan 2020 15:30:57 -0500
Subject: [PATCH 3/4] const party

---
 src/Hardware/AVR/GPIO.h | 30 +++++++++++++++---------------
 src/Hardware/SAM/GPIO.h | 32 ++++++++++++++++----------------
 2 files changed, 31 insertions(+), 31 deletions(-)

diff --git a/src/Hardware/AVR/GPIO.h b/src/Hardware/AVR/GPIO.h
index 08a4268..2d9098e 100644
--- a/src/Hardware/AVR/GPIO.h
+++ b/src/Hardware/AVR/GPIO.h
@@ -34,14 +34,14 @@ class GPIO {
   /**
    * Return the encapsulated pin
    */
-  unsigned int pin() {
+  unsigned int pin() const {
     return (unsigned int) PIN;
   }
   
   /**
    * Set pin to input mode.
    */
-  GPIO<PIN>& input()
+  const GPIO<PIN>& input() const
     __attribute__((always_inline))
   {
     GPIO_ATOMIC(SFR()->ddr &= ~MASK);
@@ -52,7 +52,7 @@ class GPIO {
    * Used with input() to activate internal pullup resistor on
    * input pin.
    */
-  void pullup()
+  void pullup() const
     __attribute__((always_inline))
   {
     high();
@@ -61,7 +61,7 @@ class GPIO {
   /**
    * Set pin to output mode.
    */
-  void output()
+  void output() const
     __attribute__((always_inline))
   {
     GPIO_ATOMIC(SFR()->ddr |= MASK);
@@ -70,7 +70,7 @@ class GPIO {
   /**
    * Open-drain pin. Use input() for high and output() for low.
    */
-  void open_drain()
+  void open_drain() const
     __attribute__((always_inline))
   {
     input();
@@ -81,7 +81,7 @@ class GPIO {
    * Return current pin state.
    * @return state.
    */
-  bool read()
+  bool read() const
     __attribute__((always_inline))
   {
     return ((SFR()->pin & MASK) != 0);
@@ -91,7 +91,7 @@ class GPIO {
    * Return current pin state. Shorthand for read().
    * @return state.
    */
-  operator bool()
+  operator bool() const
     __attribute__((always_inline))
   {
     return (read());
@@ -100,7 +100,7 @@ class GPIO {
   /**
    * Set pin low(0). Shorthand for write(LOW).
    */
-  void low()
+  void low() const
     __attribute__((always_inline))
   {
     GPIO_ATOMIC(SFR()->port &= ~MASK);
@@ -109,7 +109,7 @@ class GPIO {
   /**
    * Set pin high(1). Shorthand for write(HIGH).
    */
-  void high()
+  void high() const
     __attribute__((always_inline))
   {
     GPIO_ATOMIC(SFR()->port |= MASK);
@@ -118,7 +118,7 @@ class GPIO {
   /**
    * Toggle pin state. Shorthand for write(!read()).
    */
-  void toggle()
+  void toggle() const
     __attribute__((always_inline))
   {
     GPIO_ATOMIC(SFR()->pin |= MASK);
@@ -129,7 +129,7 @@ class GPIO {
    * and zero value will set the pin LOW(0).
    * @param[in] value to set pin.
    */
-  void write(int value)
+  void write(int value) const
     __attribute__((always_inline))
   {
     if (value) high(); else low();
@@ -140,7 +140,7 @@ class GPIO {
    * and zero value will set the pin LOW(0). Shorthand for write(value).
    * @param[in] value to set pin.
    */
-  void operator=(int value)
+  void operator=(int value) const
     __attribute__((always_inline))
   {
     write(value);
@@ -151,7 +151,7 @@ class GPIO {
    * are disabled while generating the pulse.
    * @param[in] width in micro-seconds.
    */
-  void pulse(uint16_t width)
+  void pulse(uint16_t width) const
   {
     if (width == 0) return;
     uint16_t count = ((width * (F_CPU / 1000000L)) / 4);
@@ -168,7 +168,7 @@ class GPIO {
    * Detect pulse and return width in micro-seconds.
    * @return width in micro-seconds.
    */
-  int pulse()
+  int pulse() const
   {
     bool s0 = read();
     while (read() == s0);
@@ -189,7 +189,7 @@ class GPIO {
    * Return pointer to control registers.
    * @return pointer.
    */
-  gpio_reg_t* SFR()
+  gpio_reg_t* SFR() const
     __attribute__((always_inline))
   {
     return ((gpio_reg_t*) GPIO_REG(PIN));
diff --git a/src/Hardware/SAM/GPIO.h b/src/Hardware/SAM/GPIO.h
index a8e49e1..dc66b0b 100644
--- a/src/Hardware/SAM/GPIO.h
+++ b/src/Hardware/SAM/GPIO.h
@@ -33,7 +33,7 @@ class GPIO {
   /**
    * Return the encapsulated pin
    */
-  unsigned int pin() {
+  unsigned int pin() const {
     return (unsigned int) PIN;
   }
   
@@ -49,7 +49,7 @@ class GPIO {
   /**
    * Set pin to input mode.
    */
-  GPIO<PIN>& input()
+  GPIO<PIN>& input() const
     __attribute__((always_inline))
   {
     SFR()->PIO_ODR = MASK;
@@ -60,7 +60,7 @@ class GPIO {
    * Used with input() to activate internal pullup resistor on
    * input pin.
    */
-  void pullup()
+  void pullup() const
     __attribute__((always_inline))
   {
     SFR()->PIO_PUER = MASK;
@@ -69,7 +69,7 @@ class GPIO {
   /**
    * Set pin to output mode.
    */
-  void output()
+  void output() const
     __attribute__((always_inline))
   {
     SFR()->PIO_OER = MASK;
@@ -78,7 +78,7 @@ class GPIO {
   /**
    * Open-drain pin. Use input() for high and output() for low.
    */
-  void open_drain()
+  void open_drain() const
     __attribute__((always_inline))
   {
     SFR()->PIO_CODR = MASK;
@@ -89,7 +89,7 @@ class GPIO {
    * Return current pin state.
    * @return state.
    */
-  bool read()
+  bool read() const
     __attribute__((always_inline))
   {
     return ((SFR()->PIO_PDSR & MASK) != 0);
@@ -99,7 +99,7 @@ class GPIO {
    * Return current pin state. Shorthand for read().
    * @return state.
    */
-  operator bool()
+  operator bool() const
     __attribute__((always_inline))
   {
     return (read());
@@ -108,7 +108,7 @@ class GPIO {
   /**
    * Set pin low(0). Shorthand for write(LOW).
    */
-  void low()
+  void low() const
     __attribute__((always_inline))
   {
     SFR()->PIO_CODR = MASK;
@@ -117,7 +117,7 @@ class GPIO {
   /**
    * Set pin high(1). Shorthand for write(HIGH).
    */
-  void high()
+  void high() const
     __attribute__((always_inline))
   {
     SFR()->PIO_SODR = MASK;
@@ -126,7 +126,7 @@ class GPIO {
   /**
    * Toggle pin state. Shorthand for write(!read()).
    */
-  void toggle()
+  void toggle() const
     __attribute__((always_inline))
   {
     write(!read());
@@ -137,7 +137,7 @@ class GPIO {
    * and zero value will set the pin LOW(0).
    * @param[in] value to set pin.
    */
-  void write(int value)
+  void write(int value) const
     __attribute__((always_inline))
   {
     if (value) high(); else low();
@@ -148,7 +148,7 @@ class GPIO {
    * and zero value will set the pin LOW(0). Shorthand for write(value).
    * @param[in] value to set pin.
    */
-  void operator=(int value)
+  void operator=(int value) const
     __attribute__((always_inline))
   {
     write(value);
@@ -159,7 +159,7 @@ class GPIO {
    * are disabled while generating the pulse.
    * @param[in] width in micro-seconds.
    */
-  void pulse(uint16_t width)
+  void pulse(uint16_t width) const
   {
     if (width == 0) return;
     toggle();
@@ -171,7 +171,7 @@ class GPIO {
    * Detect pulse and return width in micro-seconds.
    * @return width in micro-seconds.
    */
-  int pulse()
+  int pulse() const
   {
     bool s0 = read();
     while (read() == s0);
@@ -188,7 +188,7 @@ class GPIO {
    * Return pointer to control registers.
    * @return pointer.
    */
-  Pio* SFR()
+  Pio* SFR() const
     __attribute__((always_inline))
   {
     switch (GPIO_REG(PIN)) {
@@ -204,7 +204,7 @@ class GPIO {
    * Return parallel input/output port identity.
    * @return identity.
    */
-  uint32_t ID_PIO()
+  uint32_t ID_PIO() const
     __attribute__((always_inline))
   {
     switch (GPIO_REG(PIN)) {

From df976dede6e676c107991460a64adf5295fba9b8 Mon Sep 17 00:00:00 2001
From: Donald Linton <lintond@gmail.com>
Date: Sun, 26 Jan 2020 07:28:08 -0500
Subject: [PATCH 4/4] benchmarks for IGPIO.h interface and virtual classes

---
 examples/BenchmarkI/BenchmarkI.ino | 186 +++++++----------------------
 examples/BenchmarkV/BenchmarkV.ino |  39 +-----
 src/IGPIO.h                        |  60 +++++-----
 3 files changed, 72 insertions(+), 213 deletions(-)

diff --git a/examples/BenchmarkI/BenchmarkI.ino b/examples/BenchmarkI/BenchmarkI.ino
index ed848d4..cb403fa 100644
--- a/examples/BenchmarkI/BenchmarkI.ino
+++ b/examples/BenchmarkI/BenchmarkI.ino
@@ -1,152 +1,48 @@
-#include "GPIO.h"
+#include "IGPIO.h"
 #include "benchmark.h"
 
 /* 
- *  NANO GPIO
-16:06:16.704 -> 1.1 Arduino core digitalRead: 3.836
-16:06:16.704 -> 1.2 Arduino core digitalWrite(HIGH): 4.216
-16:06:16.704 -> 1.3 Arduino core digitalWrite(LOW): 4.088
-16:06:16.739 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 8.236
-16:06:16.739 -> 1.5 Arduino core toggle; digitalWrite: 8.304
-16:06:16.774 -> 2.1 GPIO pin value operator: 0.064
-16:06:16.774 -> 2.2 GPIO high member function: 0.128
-16:06:16.774 -> 2.3 GPIO low member function: 0.132
-16:06:16.774 -> 2.4 GPIO assignment HIGH: 0.132
-16:06:16.774 -> 2.5 GPIO assignment LOW: 0.132
-16:06:16.807 -> 2.6 GPIO toggle; value and assignment operator: 0.344
-16:06:16.807 -> 2.7 GPIO toggle; high and low member functions: 0.248
-16:06:16.807 -> 2.8 GPIO toggle; assignment operator, HIGH/LOW: 0.248
-16:06:16.807 -> 2.9 GPIO toggle member function: 0.124
-16:06:16.843 ->
-  
-  NANO VGPIO
-16:10:40.288 -> 1.1 Arduino core digitalRead: 3.836
-16:10:40.288 -> 1.2 Arduino core digitalWrite(HIGH): 4.216
-16:10:40.321 -> 1.3 Arduino core digitalWrite(LOW): 4.084
-16:10:40.321 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 8.236
-16:10:40.321 -> 1.5 Arduino core toggle; digitalWrite: 8.304
-16:10:40.356 -> 2.1 VGPIO pin value operator: 0.064
-16:10:40.356 -> 2.2 VGPIO high member function: 0.756
-16:10:40.356 -> 2.3 VGPIO low member function: 0.756
-16:10:40.390 -> 2.4 VGPIO assignment HIGH: 0.132
-16:10:40.390 -> 2.5 VGPIO assignment LOW: 0.132
-16:10:40.390 -> 2.6 VGPIO toggle; value and assignment operator: 1.356
-16:10:40.390 -> 2.7 VGPIO toggle; high and low member functions: 1.512
-16:10:40.424 -> 2.8 VGPIO toggle; assignment operator, HIGH/LOW: 0.256
-16:10:40.424 -> 2.9 VGPIO toggle member function: 0.756
-16:10:40.424 -> 
-
-   NANO IGPIO
-16:20:32.106 -> 1.1 Arduino core digitalRead: 3.840
-16:20:32.106 -> 1.2 Arduino core digitalWrite(HIGH): 4.216
-16:20:32.140 -> 1.3 Arduino core digitalWrite(LOW): 4.084
-16:20:32.140 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 8.236
-16:20:32.175 -> 1.5 Arduino core toggle; digitalWrite: 8.304
-16:20:32.175 -> 2.1 IGPIO pin value operator: 1.512
-16:20:32.175 -> 2.2 IGPIO high member function: 1.448
-16:20:32.212 -> 2.3 IGPIO low member function: 1.452
-16:20:32.212 -> 2.4 IGPIO assignment HIGH: 1.700
-16:20:32.212 -> 2.5 IGPIO assignment LOW: 1.764
-16:20:32.212 -> 2.6 IGPIO toggle; value and assignment operator: 2.924
-16:20:32.246 -> 2.7 IGPIO toggle; high and low member functions: 2.896
-16:20:32.246 -> 2.8 IGPIO toggle; assignment operator, HIGH/LOW: 3.460
-16:20:32.246 -> 2.9 IGPIO toggle member function: 1.444
-16:20:32.281 -> 
-
-  MEGA GPIO
-16:26:50.265 -> 1.1 Arduino core digitalRead: 6.412
-16:26:50.299 -> 1.2 Arduino core digitalWrite(HIGH): 6.916
-16:26:50.299 -> 1.3 Arduino core digitalWrite(LOW): 6.792
-16:26:50.332 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 13.204
-16:26:50.366 -> 1.5 Arduino core toggle; digitalWrite: 13.712
-16:26:50.366 -> 2.1 GPIO pin value operator: 0.064
-16:26:50.366 -> 2.2 GPIO high member function: 0.124
-16:26:50.366 -> 2.3 GPIO low member function: 0.124
-16:26:50.401 -> 2.4 GPIO assignment HIGH: 0.124
-16:26:50.401 -> 2.5 GPIO assignment LOW: 0.128
-16:26:50.401 -> 2.6 GPIO toggle; value and assignment operator: 0.352
-16:26:50.401 -> 2.7 GPIO toggle; high and low member functions: 0.256
-16:26:50.434 -> 2.8 GPIO toggle; assignment operator, HIGH/LOW: 0.248
-16:26:50.434 -> 2.9 GPIO toggle member function: 0.132
-16:26:50.434 -> 3.1 Arduino core digitalRead: 6.284
-16:26:50.468 -> 3.2 Arduino core digitalWrite(HIGH): 7.168
-16:26:50.468 -> 3.3 Arduino core digitalWrite(LOW): 7.048
-16:26:50.468 -> 3.4 Arduino core toggle; digitalRead-digitalWrite: 13.652
-16:26:50.502 -> 3.5 Arduino core toggle; digitalWrite: 14.208
-16:26:50.536 -> 4.1 GPIO pin value operator: 0.128
-16:26:50.536 -> 4.2 GPIO high member function: 0.504
-16:26:50.536 -> 4.3 GPIO low member function: 0.504
-16:26:50.536 -> 4.4 GPIO assignment HIGH: 0.508
-16:26:50.571 -> 4.5 GPIO assignment LOW: 0.504
-16:26:50.571 -> 4.6 GPIO toggle; value and assignment operator: 0.944
-16:26:50.571 -> 4.7 GPIO toggle; high and low member functions: 1.008
-16:26:50.571 -> 4.8 GPIO toggle; assignment operator: 1.012
-16:26:50.606 -> 4.9 GPIO toggle member function: 0.500
-16:26:50.606 -> 
-  
-  MEGA VGPIO
-16:26:20.659 -> 1.1 Arduino core digitalRead: 6.412
-16:26:20.659 -> 1.2 Arduino core digitalWrite(HIGH): 6.920
-16:26:20.693 -> 1.3 Arduino core digitalWrite(LOW): 6.796
-16:26:20.693 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 13.204
-16:26:20.728 -> 1.5 Arduino core toggle; digitalWrite: 13.712
-16:26:20.761 -> 2.1 VGPIO pin value operator: 0.068
-16:26:20.761 -> 2.2 VGPIO high member function: 0.820
-16:26:20.761 -> 2.3 VGPIO low member function: 0.820
-16:26:20.761 -> 2.4 VGPIO assignment HIGH: 0.124
-16:26:20.761 -> 2.5 VGPIO assignment LOW: 0.124
-16:26:20.795 -> 2.6 VGPIO toggle; value and assignment operator: 1.660
-16:26:20.795 -> 2.7 VGPIO toggle; high and low member functions: 1.636
-16:26:20.795 -> 2.8 VGPIO toggle; assignment operator, HIGH/LOW: 0.256
-16:26:20.829 -> 2.9 VGPIO toggle member function: 0.820
-16:26:20.829 -> 3.1 Arduino core digitalRead: 6.356
-16:26:20.829 -> 3.2 Arduino core digitalWrite(HIGH): 7.232
-16:26:20.864 -> 3.3 Arduino core digitalWrite(LOW): 7.104
-16:26:20.864 -> 3.4 Arduino core toggle; digitalRead-digitalWrite: 13.768
-16:26:20.899 -> 3.5 Arduino core toggle; digitalWrite: 14.344
-16:26:20.899 -> 4.1 VGPIO pin value operator: 0.132
-16:26:20.932 -> 4.2 VGPIO high member function: 1.448
-16:26:20.932 -> 4.3 VGPIO low member function: 1.448
-16:26:20.932 -> 4.4 VGPIO assignment HIGH: 1.576
-16:26:20.932 -> 4.5 VGPIO assignment LOW: 1.764
-16:26:20.966 -> 4.6 VGPIO toggle; value and assignment operator: 2.072
-16:26:20.966 -> 4.7 VGPIO toggle; high and low member functions: 2.892
-16:26:20.966 -> 4.8 VGPIO toggle; assignment operator: 3.332
-16:26:21.000 -> 4.9 VGPIO toggle member function: 1.452
-16:26:21.000 -> 
-  
+ *  UNO GPIO baseline
+07:13:50.128 -> 1.1 Arduino core digitalRead: 3.836
+07:13:50.128 -> 1.2 Arduino core digitalWrite(HIGH): 4.216
+07:13:50.128 -> 1.3 Arduino core digitalWrite(LOW): 4.088
+07:13:50.162 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 8.236
+07:13:50.162 -> 1.5 Arduino core toggle; digitalWrite: 8.304
+
+07:13:50.197 -> 2.1 GPIO pin value operator: 0.064
+07:13:50.197 -> 2.2 GPIO high member function: 0.128
+07:13:50.197 -> 2.3 GPIO low member function: 0.132
+07:13:50.197 -> 2.4 GPIO assignment HIGH: 0.132
+07:13:50.197 -> 2.5 GPIO assignment LOW: 0.132
+07:13:50.234 -> 2.6 GPIO toggle; value and assignment operator: 0.344
+07:13:50.234 -> 2.7 GPIO toggle; high and low member functions: 0.248
+07:13:50.234 -> 2.8 GPIO toggle; assignment operator, HIGH/LOW: 0.248
+07:13:50.234 -> 2.9 GPIO toggle member function: 0.124
+
+ *  UNO VGPIO
+07:12:45.468 -> 2.1 VGPIO pin value operator: 0.064
+07:12:45.468 -> 2.2 VGPIO high member function: 0.756
+07:12:45.468 -> 2.3 VGPIO low member function: 0.756
+07:12:45.503 -> 2.4 VGPIO assignment HIGH: 0.132
+07:12:45.503 -> 2.5 VGPIO assignment LOW: 0.132
+07:12:45.503 -> 2.6 VGPIO toggle; value and assignment operator: 1.356
+07:12:45.503 -> 2.7 VGPIO toggle; high and low member functions: 1.512
+07:12:45.538 -> 2.8 VGPIO toggle; assignment operator, HIGH/LOW: 0.256
+07:12:45.538 -> 2.9 VGPIO toggle member function: 0.756
+
+ *  UNO IGPIO
+1.1 Arduino core digitalRead: 3.840
+07:10:08.171 -> 2.1 IGPIO pin value operator: 1.512
+07:10:08.171 -> 2.2 IGPIO high member function: 1.448
+07:10:08.171 -> 2.3 IGPIO low member function: 1.452
+07:10:08.206 -> 2.4 IGPIO assignment HIGH: 1.700
+07:10:08.206 -> 2.5 IGPIO assignment LOW: 1.764
+07:10:08.206 -> 2.6 IGPIO toggle; value and assignment operator: 2.924
+07:10:08.206 -> 2.7 IGPIO toggle; high and low member functions: 2.892
+07:10:08.240 -> 2.8 IGPIO toggle; assignment operator, HIGH/LOW: 3.456
+07:10:08.240 -> 2.9 IGPIO toggle member function: 1.452
+07:10:08.275 -> 
 
-  MEGA IGPIO
-16:24:12.181 -> 1.1 Arduino core digitalRead: 6.420
-16:24:12.181 -> 1.2 Arduino core digitalWrite(HIGH): 6.920
-16:24:12.181 -> 1.3 Arduino core digitalWrite(LOW): 6.792
-16:24:12.216 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 13.212
-16:24:12.251 -> 1.5 Arduino core toggle; digitalWrite: 13.704
-16:24:12.251 -> 2.1 IGPIO pin value operator: 1.700
-16:24:12.251 -> 2.2 IGPIO high member function: 1.572
-16:24:12.286 -> 2.3 IGPIO low member function: 1.572
-16:24:12.286 -> 2.4 IGPIO assignment HIGH: 1.828
-16:24:12.286 -> 2.5 IGPIO assignment LOW: 1.884
-16:24:12.286 -> 2.6 IGPIO toggle; value and assignment operator: 3.176
-16:24:12.319 -> 2.7 IGPIO toggle; high and low member functions: 3.152
-16:24:12.319 -> 2.8 IGPIO toggle; assignment operator, HIGH/LOW: 3.712
-16:24:12.352 -> 2.9 IGPIO toggle member function: 1.572
-16:24:12.352 -> 3.1 Arduino core digitalRead: 6.356
-16:24:12.352 -> 3.2 Arduino core digitalWrite(HIGH): 7.236
-16:24:12.386 -> 3.3 Arduino core digitalWrite(LOW): 7.108
-16:24:12.386 -> 3.4 Arduino core toggle; digitalRead-digitalWrite: 13.776
-16:24:12.421 -> 3.5 Arduino core toggle; digitalWrite: 14.336
-16:24:12.421 -> 4.1 IGPIO pin value operator: 1.140
-16:24:12.455 -> 4.2 IGPIO high member function: 1.452
-16:24:12.455 -> 4.3 IGPIO low member function: 1.444
-16:24:12.455 -> 4.4 IGPIO assignment HIGH: 1.576
-16:24:12.455 -> 4.5 IGPIO assignment LOW: 1.760
-16:24:12.488 -> 4.6 IGPIO toggle; value and assignment operator: 2.076
-16:24:12.488 -> 4.7 IGPIO toggle; high and low member functions: 2.896
-16:24:12.488 -> 4.8 IGPIO toggle; assignment operator: 3.328
-16:24:12.523 -> 4.9 IGPIO toggle member function: 1.452
-16:24:12.523 -> 
-  
  */
 const IGPIO& button = VGPIO<BOARD::D12>();
 const IGPIO& led = VGPIO<BOARD::D13>();
diff --git a/examples/BenchmarkV/BenchmarkV.ino b/examples/BenchmarkV/BenchmarkV.ino
index e6acbe0..acd16fe 100644
--- a/examples/BenchmarkV/BenchmarkV.ino
+++ b/examples/BenchmarkV/BenchmarkV.ino
@@ -1,43 +1,6 @@
-#include "GPIO.h"
+#include "IGPIO.h"
 #include "benchmark.h"
 
-/* 
- *  NANO GPIO
-16:06:16.704 -> 1.1 Arduino core digitalRead: 3.836
-16:06:16.704 -> 1.2 Arduino core digitalWrite(HIGH): 4.216
-16:06:16.704 -> 1.3 Arduino core digitalWrite(LOW): 4.088
-16:06:16.739 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 8.236
-16:06:16.739 -> 1.5 Arduino core toggle; digitalWrite: 8.304
-16:06:16.774 -> 2.1 GPIO pin value operator: 0.064
-16:06:16.774 -> 2.2 GPIO high member function: 0.128
-16:06:16.774 -> 2.3 GPIO low member function: 0.132
-16:06:16.774 -> 2.4 GPIO assignment HIGH: 0.132
-16:06:16.774 -> 2.5 GPIO assignment LOW: 0.132
-16:06:16.807 -> 2.6 GPIO toggle; value and assignment operator: 0.344
-16:06:16.807 -> 2.7 GPIO toggle; high and low member functions: 0.248
-16:06:16.807 -> 2.8 GPIO toggle; assignment operator, HIGH/LOW: 0.248
-16:06:16.807 -> 2.9 GPIO toggle member function: 0.124
-16:06:16.843 ->
-  
-  NANO VGPIO
-16:10:40.288 -> 1.1 Arduino core digitalRead: 3.836
-16:10:40.288 -> 1.2 Arduino core digitalWrite(HIGH): 4.216
-16:10:40.321 -> 1.3 Arduino core digitalWrite(LOW): 4.084
-16:10:40.321 -> 1.4 Arduino core toggle; digitalRead-digitalWrite: 8.236
-16:10:40.321 -> 1.5 Arduino core toggle; digitalWrite: 8.304
-16:10:40.356 -> 2.1 VGPIO pin value operator: 0.064
-16:10:40.356 -> 2.2 VGPIO high member function: 0.756
-16:10:40.356 -> 2.3 VGPIO low member function: 0.756
-16:10:40.390 -> 2.4 VGPIO assignment HIGH: 0.132
-16:10:40.390 -> 2.5 VGPIO assignment LOW: 0.132
-16:10:40.390 -> 2.6 VGPIO toggle; value and assignment operator: 1.356
-16:10:40.390 -> 2.7 VGPIO toggle; high and low member functions: 1.512
-16:10:40.424 -> 2.8 VGPIO toggle; assignment operator, HIGH/LOW: 0.256
-16:10:40.424 -> 2.9 VGPIO toggle member function: 0.756
-16:10:40.424 -> 
-
-
- */
 VGPIO<BOARD::D12> button;
 VGPIO<BOARD::D13> led;
 #define BUTTON_PIN 12
diff --git a/src/IGPIO.h b/src/IGPIO.h
index a19f048..9ef2f64 100644
--- a/src/IGPIO.h
+++ b/src/IGPIO.h
@@ -46,108 +46,108 @@ class IGPIO {
     /**
      * Test if another IGPIO object uses the same pin.
      */
-    inline bool operator==(IGPIO &that) { return pin() == that.pin(); }
+    inline bool operator==(IGPIO &that) const { return pin() == that.pin(); }
 
     /**
      * Get the assigned pin.
      */
-    virtual unsigned int pin() = 0;
+    virtual unsigned int pin() const = 0;
 
     /**
      * Set pin to input mode.
      */
-    virtual void input() = 0;
+    virtual void input() const = 0;
 
     /**
      * Used with input() to activate internal pullup resistor on
      * input pin.
      */
-    virtual void pullup() = 0;
+    virtual void pullup() const = 0;
 
     /**
      * Set pin to output mode.
      */
-    virtual void output() = 0;
+    virtual void output() const = 0;
 
     /**
      * Open-drain pin. Use input() for high and output() for low.
      */
-    virtual void open_drain() = 0;
+    virtual void open_drain() const = 0;
 
     /**
      * Return current pin state.
      * @return state.
      */
-    virtual bool read() = 0;
+    virtual bool read() const = 0;
 
     /**
      * Return current pin state. Shorthand for read().
      * @return state.
      */
-    virtual operator bool() = 0;
+    virtual operator bool() const = 0;
 
     /**
      * Set pin low(0). Shorthand for write(LOW).
      */
-    virtual void low() = 0;
+    virtual void low() const = 0;
 
     /**
      * Set pin high(1). Shorthand for write(HIGH).
      */
-    virtual void high() = 0;
+    virtual void high() const = 0;
 
     /**
      * Toggle pin state. Shorthand for write(!read()).
      */
-    virtual void toggle() = 0;
+    virtual void toggle() const = 0;
 
     /**
      * Set pin to given state. Non-zero value will set the pin HIGH(1),
      * and zero value will set the pin LOW(0).
      * @param[in] value to set pin.
      */
-    virtual void write(int value) = 0;
+    virtual void write(int value) const = 0;
 
     /**
      * Set pin to given state. Non-zero value will set the pin HIGH(1),
      * and zero value will set the pin LOW(0). Shorthand for write(value).
      * @param[in] value to set pin.
      */
-    virtual void operator=(int value) = 0;
+    virtual void operator=(int value) const = 0;
 
     /**
      * Generate pulse with given width in micro-seconds. Interrupts
      * are disabled while generating the pulse.
      * @param[in] width in micro-seconds.
      */
-    virtual void pulse(uint16_t width) = 0;
+    virtual void pulse(uint16_t width) const = 0;
 
     /**
      * Detect pulse and return width in micro-seconds.
      * @return width in micro-seconds.
      */
-    virtual int pulse() = 0;
+    virtual int pulse() const = 0;
 };
 
 
 template<BOARD::pin_t PIN>
 class VGPIO : public IGPIO, public GPIO<PIN> {
   public:
-    inline bool operator==(IGPIO &that) { return pin() == that.pin(); }
-    unsigned int pin() { return GPIO<PIN>::pin(); }
-    void input() { GPIO<PIN>::input(); }
-    void pullup() { GPIO<PIN>::pullup(); }
-    void output() { GPIO<PIN>::output(); } 
-    void open_drain() { GPIO<PIN>::open_drain(); }
-    bool read() { return GPIO<PIN>::read(); }
-    operator bool() { return GPIO<PIN>::read(); }
-    void low() { GPIO<PIN>::low(); }
-    void high() { GPIO<PIN>::high(); }
-    void toggle() { GPIO<PIN>::toggle(); }
-    void write(int value)  { GPIO<PIN>::write(value); };
-    void operator=(int value)  { GPIO<PIN>::write(value); }
-    void pulse(uint16_t width) { GPIO<PIN>::pulse(width); }
-    int pulse() { return GPIO<PIN>::pulse(); }
+    inline bool operator==(IGPIO &that) const { return pin() == that.pin(); }
+    unsigned int pin() const { return GPIO<PIN>::pin(); }
+    void input() const { GPIO<PIN>::input(); }
+    void pullup() const { GPIO<PIN>::pullup(); }
+    void output() const { GPIO<PIN>::output(); } 
+    void open_drain() const { GPIO<PIN>::open_drain(); }
+    bool read() const { return GPIO<PIN>::read(); }
+    operator bool() const { return GPIO<PIN>::read(); }
+    void low() const { GPIO<PIN>::low(); }
+    void high() const { GPIO<PIN>::high(); }
+    void toggle() const { GPIO<PIN>::toggle(); }
+    void write(int value) const  { GPIO<PIN>::write(value); };
+    void operator=(int value) const  { GPIO<PIN>::write(value); }
+    void pulse(uint16_t width) const { GPIO<PIN>::pulse(width); }
+    int pulse() const { return GPIO<PIN>::pulse(); }
 
 };