Precise delay broken whenever beyond precise duration. (plerup#264)

* Precise delay broken whenever beyond precise duration.
* Fix lazy delay for interrupt sensitive applications

Author: dok-net

library.json

@@ -1,6 +1,6 @@
 {
     "name": "EspSoftwareSerial",
-    "version": "6.17.0",
+    "version": "6.17.1",
     "description": "Implementation of the Arduino software serial for ESP8266/ESP32.",
     "keywords": [
         "serial", "io", "softwareserial"

library.properties

@@ -1,5 +1,5 @@
 name=EspSoftwareSerial
-version=6.17.0
+version=6.17.1
 author=Dirk Kaar, Peter Lerup
 maintainer=Dirk Kaar <dok@dok-net.net>
 sentence=Implementation of the Arduino software serial for ESP8266/ESP32.

src/SoftwareSerial.cpp

@@ -351,16 +351,19 @@ void SoftwareSerial::lazyDelay() {
     {
         optimistic_yield(10000UL);
     }
+    // Assure that below-ms part of delays are not elided
+    preciseDelay();
     // Disable interrupts again if applicable
     if (!m_intTxEnabled) { disableInterrupts(); }
-    preciseDelay();
 }
 
 void IRAM_ATTR SoftwareSerial::preciseDelay() {
     uint32_t ticks;
+    uint32_t expired;
     do {
         ticks = microsToTicks(micros());
-    } while ((ticks - m_periodStart) < m_periodDuration);
+        expired =  ticks - m_periodStart;
+    } while (static_cast<int32_t>(m_periodDuration - expired) > 0);
     m_periodDuration = 0;
     m_periodStart = ticks;
 }