Add optional virtual to DigitalIn/Out/InOut methods

This commit introduces configuration options to make certain methods of the `DigitalIn`, `DigitalOut`, and `DigitalInOut` classes virtual. This is useful when more advanced features of polymorphism are required. This is not enabled by default to optimize these classes for execution speed and code size.

Enabling this option will slightly increase latency of calling the virtual methods and will increase the ROM/RAM footprint of the class.

The configuration can be changed by overriding the options: `drivers.virtualize-digitalin` (and so on, for each class involved in the commit).

Author: AGlass0fMilk

drivers/include/drivers/DigitalIn.h

@@ -1,5 +1,5 @@
 /* mbed Microcontroller Library
- * Copyright (c) 2006-2019 ARM Limited
+ * Copyright (c) 2006-2020 ARM Limited
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -21,6 +21,14 @@
 
 #include "hal/gpio_api.h"
 
+/**
+ * Option to make certain class functions virtual for advanced polymorphism.
+ * Disabled by default for size and speed optimization.
+ */
+#ifndef MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALIN
+#define MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALIN false
+#endif
+
 namespace mbed {
 /**
  * \defgroup drivers_DigitalIn DigitalIn class
@@ -75,13 +83,28 @@ class DigitalIn {
         gpio_init_in_ex(&gpio, pin, mode);
     }
 
+    /** Class destructor, deinitialize the pin
+     */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALIN
+    virtual ~DigitalIn()
+#else
+    ~DigitalIn()
+#endif
+    {
+        gpio_free(&gpio);
+    }
+
     /** Read the input, represented as 0 or 1 (int)
      *
      *  @returns
      *    An integer representing the state of the input pin,
      *    0 for logical 0, 1 for logical 1
      */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALIN
+    virtual int read()
+#else
     int read()
+#endif
     {
         // Thread safe / atomic HAL call
         return gpio_read(&gpio);
@@ -91,15 +114,23 @@ class DigitalIn {
      *
      *  @param pull PullUp, PullDown, PullNone, OpenDrain
      */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALIN
+    virtual void mode(PinMode pull);
+#else
     void mode(PinMode pull);
+#endif
 
     /** Return the output setting, represented as 0 or 1 (int)
      *
      *  @returns
      *    Non zero value if pin is connected to uc GPIO
      *    0 if gpio object was initialized with NC
      */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALIN
+    virtual int is_connected()
+#else
     int is_connected()
+#endif
     {
         // Thread safe / atomic HAL call
         return gpio_is_connected(&gpio);

drivers/include/drivers/DigitalInOut.h

@@ -1,5 +1,5 @@
 /* mbed Microcontroller Library
- * Copyright (c) 2006-2019 ARM Limited
+ * Copyright (c) 2006-2020 ARM Limited
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -21,6 +21,14 @@
 
 #include "hal/gpio_api.h"
 
+/**
+ * Option to make certain class functions virtual for advanced polymorphism.
+ * Disabled by default for size and speed optimization.
+ */
+#ifndef MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALINOUT
+#define MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALINOUT false
+#endif
+
 namespace mbed {
 /**
  * \defgroup drivers_DigitalInOut DigitalInOut class
@@ -58,12 +66,27 @@ class DigitalInOut {
         gpio_init_inout(&gpio, pin, direction, mode, value);
     }
 
+    /** Class destructor, deinitialize the pin
+     */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALINOUT
+    virtual ~DigitalInOut()
+#else
+    ~DigitalInOut()
+#endif
+    {
+        gpio_free(&gpio);
+    }
+
     /** Set the output, specified as 0 or 1 (int)
      *
      *  @param value An integer specifying the pin output value,
      *      0 for logical 0, 1 (or any other non-zero value) for logical 1
      */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALINOUT
+    virtual void write(int value)
+#else
     void write(int value)
+#endif
     {
         // Thread safe / atomic HAL call
         gpio_write(&gpio, value);
@@ -75,33 +98,53 @@ class DigitalInOut {
      *    an integer representing the output setting of the pin if it is an output,
      *    or read the input if set as an input
      */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALINOUT
+    virtual int read()
+#else
     int read()
+#endif
     {
         // Thread safe / atomic HAL call
         return gpio_read(&gpio);
     }
 
     /** Set as an output
      */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALINOUT
+    virtual void output();
+#else
     void output();
+#endif
 
     /** Set as an input
      */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALINOUT
+    virtual void input();
+#else
     void input();
+#endif
 
     /** Set the input pin mode
      *
      *  @param pull PullUp, PullDown, PullNone, OpenDrain
      */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALINOUT
+    virtual void mode(PinMode pull);
+#else
     void mode(PinMode pull);
+#endif
 
     /** Return the output setting, represented as 0 or 1 (int)
      *
      *  @returns
      *    Non zero value if pin is connected to uc GPIO
      *    0 if gpio object was initialized with NC
      */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALINOUT
+    virtual int is_connected()
+#else
     int is_connected()
+#endif
     {
         // Thread safe / atomic HAL call
         return gpio_is_connected(&gpio);

drivers/include/drivers/DigitalOut.h

@@ -1,5 +1,5 @@
 /* mbed Microcontroller Library
- * Copyright (c) 2006-2019 ARM Limited
+ * Copyright (c) 2006-2020 ARM Limited
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -18,8 +18,17 @@
 #define MBED_DIGITALOUT_H
 
 #include "platform/platform.h"
+
 #include "hal/gpio_api.h"
 
+/**
+ * Option to make certain class functions virtual for advanced polymorphism.
+ * Disabled by default for size and speed optimization.
+ */
+#ifndef MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALOUT
+#define MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALOUT false
+#endif
+
 namespace mbed {
 /**
  * \defgroup drivers_DigitalOut DigitalOut class
@@ -70,12 +79,27 @@ class DigitalOut {
         gpio_init_out_ex(&gpio, pin, value);
     }
 
+    /** Class destructor, deinitialize the pin
+     */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALOUT
+    virtual ~DigitalOut()
+#else
+    ~DigitalOut()
+#endif
+    {
+        gpio_free(&gpio);
+    }
+
     /** Set the output, specified as 0 or 1 (int)
      *
      *  @param value An integer specifying the pin output value,
      *      0 for logical 0, 1 (or any other non-zero value) for logical 1
      */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALOUT
+    virtual void write(int value)
+#else
     void write(int value)
+#endif
     {
         // Thread safe / atomic HAL call
         gpio_write(&gpio, value);
@@ -87,7 +111,11 @@ class DigitalOut {
      *    an integer representing the output setting of the pin,
      *    0 for logical 0, 1 for logical 1
      */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALOUT
+    virtual int read()
+#else
     int read()
+#endif
     {
         // Thread safe / atomic HAL call
         return gpio_read(&gpio);
@@ -99,7 +127,11 @@ class DigitalOut {
      *    Non zero value if pin is connected to uc GPIO
      *    0 if gpio object was initialized with NC
      */
+#if MBED_CONF_DRIVERS_VIRTUALIZE_DIGITALOUT
+    virtual int is_connected()
+#else
     int is_connected()
+#endif
     {
         // Thread safe / atomic HAL call
         return gpio_is_connected(&gpio);

drivers/mbed_lib.json

@@ -85,6 +85,18 @@
         "ospi_dqs": {
             "help": "OSPI dqs pin",
             "value": "OSPI_FLASH1_DQS"
+        },
+        "virtualize-digitalout": {
+            "help": "Enable virtual functions in the DigitalOut class",
+            "value": false
+        },
+        "virtualize-digitalin": {
+            "help": "Enable virtual functions in the DigitalIn class",
+            "value": false
+        },
+        "virtualize-digitalinout": {
+            "help": "Enable virtual functions in the DigitalInOut class",
+            "value": false
         }
     }
 }