Use 'attachInterruptArg()' for RX interrupts with 'this' argument

This allows us to dispose of the ugly global table of pointers to  software serial objects. Instead those pointers are all handled in the GPIO core.

We will need to make sure to detach the interrupt (and thereby remove reference to the software serial object) when the object is destroyed.

Author: oclyke

libraries/SoftwareSerial/src/SoftwareSerial.cpp

@@ -35,10 +35,6 @@
 #include "SoftwareSerial.h"
 #include "Arduino.h"
 
-// Global Table of SoftwareSerial Pointers
-SoftwareSerial *gpSoftwareSerialObjs[AP3_GPIO_MAX_PADS];
-uint8_t gSoftwareSerialNumObjs = 0;
-
 SoftwareSerial *ap3_serial_handle = 0;
 
 //Uncomment to enable debug pulses and Serial.prints
@@ -49,74 +45,29 @@ SoftwareSerial *ap3_serial_handle = 0;
 ap3_gpio_pad_t debugPad = ap3_gpio_pin2pad(SS_DEBUG_PIN);
 #endif
 
-// Software Serial ISR (To attach to pin change interrupts)
-/*void _software_serial_isr(void)
-{
-  uint64_t gpio_int_mask = 0x00;
-  am_hal_gpio_interrupt_status_get(true, &gpio_int_mask);
-  SoftwareSerial *obj = NULL;
-  for (uint8_t indi = 0; indi < gSoftwareSerialNumObjs; indi++)
-  {
-    obj = gpSoftwareSerialObjs[indi];
-    if (obj == NULL)
-    {
-      break; // there should not be any null pointers in the global object table
-    }
-    if (obj->_rxPadBitMask & gpio_int_mask)
-    {
-      obj->rxBit();
-    }
-  }
-}*/
-inline void _software_serial_isr(void)
+inline void _software_serial_isr(void* arg)
 {
-  ap3_serial_handle->rxBit();
+  SoftwareSerial* handle = (SoftwareSerial*)arg;
+  handle->rxBit();
 }
 
 //Constructor
 SoftwareSerial::SoftwareSerial(uint8_t rxPin, uint8_t txPin, bool invertLogic)
 {
-  if (gSoftwareSerialNumObjs >= AP3_GPIO_MAX_PADS)
-  {
-    return; // Error -- no instances left to create
-  }
-
   _rxPin = rxPin;
   _txPin = txPin;
 
   _txPad = ap3_gpio_pin2pad(_txPin);
   _rxPad = ap3_gpio_pin2pad(_rxPin);
 
   _invertLogic = invertLogic;
-
-  _rxPadBitMask = (0x01 << _rxPad);
-
-  // Add to the global array
-  _indexNumber = gSoftwareSerialNumObjs;
-  gpSoftwareSerialObjs[_indexNumber] = this;
-  gSoftwareSerialNumObjs++;
 }
 
 // Destructor
 SoftwareSerial::~SoftwareSerial()
 {
-  if (gSoftwareSerialNumObjs < 1)
-  {
-    return; // error -- no instances left to destroy
-  }
-
-  // Remove from global pointer list by filtering others down:
-  uint8_t index = _indexNumber;
-  do
-  {
-    gpSoftwareSerialObjs[index] = NULL;
-    if (index < (gSoftwareSerialNumObjs - 1))
-    {
-      gpSoftwareSerialObjs[index] = gpSoftwareSerialObjs[index + 1];
-    }
-    index++;
-  } while (index < gSoftwareSerialNumObjs);
-  gSoftwareSerialNumObjs--;
+  // Todo: call an "end" function that will detach the interrupt before removing the object
+  // (otherwise rx interrupts will try to access an invalid object)
 }
 
 void SoftwareSerial::begin(uint32_t baudRate)
@@ -157,10 +108,8 @@ void SoftwareSerial::begin(uint32_t baudRate, HardwareSerial_Config_e SSconfig)
   //Clear compare interrupt
   am_hal_stimer_int_clear(AM_HAL_STIMER_INT_COMPAREH);
 
-  // Register the class into the local list
-  ap3_serial_handle = this;
-
-  attachInterrupt(digitalPinToInterrupt(_rxPin), _software_serial_isr, CHANGE);
+  // Attach argument interrupt with 'this' as argument
+  attachInterruptArg(digitalPinToInterrupt(_rxPin), _software_serial_isr, (void*)this, CHANGE);
 }
 
 int SoftwareSerial::available()

libraries/SoftwareSerial/src/SoftwareSerial.h

@@ -59,8 +59,6 @@ class SoftwareSerial
   void rxBit(void);
   void endOfByte(void);
 
-  uint64_t _rxPadBitMask;     // The AM HAL style pad bit mask associated with the RX pad
-
 private:
   void startRXListening(void);