Optimize SoftwareSerial::setRxIntMsk()

This precalculates the mask register and value, making setRxIntMask
considerably less complicated. Right now, this is not a big deal, but
simplifying it allows using it inside the ISR next.

2 files changed, 9 insertions, 2 deletions

diff --git a/libraries/SoftwareSerial/SoftwareSerial.cpp b/libraries/SoftwareSerial/SoftwareSerial.cpp
index 42f796b..bee1107 100644
--- a/libraries/SoftwareSerial/SoftwareSerial.cpp
+++ b/libraries/SoftwareSerial/SoftwareSerial.cpp
@@ -403,6 +403,11 @@ void SoftwareSerial::begin(long speed)
     // (others might also need it, so we disable the interrupt by using

     // the per-pin PCMSK register).

     *digitalPinToPCICR(_receivePin) |= _BV(digitalPinToPCICRbit(_receivePin));

+    // Precalculate the pcint mask register and value, so setRxIntMask

+    // can be used inside the ISR without costing too much time.

+    _pcint_maskreg = digitalPinToPCMSK(_receivePin);

+    _pcint_maskvalue = _BV(digitalPinToPCMSKbit(_receivePin));

+

     tunedDelay(_tx_delay); // if we were low this establishes the end

   }

 

@@ -417,9 +422,9 @@ void SoftwareSerial::begin(long speed)
 void SoftwareSerial::setRxIntMsk(bool enable)

 {

     if (enable)

-      *digitalPinToPCMSK(_receivePin) |= _BV(digitalPinToPCMSKbit(_receivePin));

+      *_pcint_maskreg |= _pcint_maskvalue;

     else

-      *digitalPinToPCMSK(_receivePin) &= ~_BV(digitalPinToPCMSKbit(_receivePin));

+      *_pcint_maskreg &= ~_pcint_maskvalue;

 }

 

 void SoftwareSerial::end()

diff --git a/libraries/SoftwareSerial/SoftwareSerial.h b/libraries/SoftwareSerial/SoftwareSerial.h
index aa9bbf3..302a23b 100644
--- a/libraries/SoftwareSerial/SoftwareSerial.h
+++ b/libraries/SoftwareSerial/SoftwareSerial.h
@@ -53,6 +53,8 @@ private:
   volatile uint8_t *_receivePortRegister;

   uint8_t _transmitBitMask;

   volatile uint8_t *_transmitPortRegister;

+  volatile uint8_t *_pcint_maskreg;

+  uint8_t _pcint_maskvalue;

 

   uint16_t _rx_delay_centering;

   uint16_t _rx_delay_intrabit;