Avoid read-modify-write when enabling SERCOM DRE interrupt

Kees Bakker · sandeepmistry · commit fd15a1c603de · 2017-12-11T08:55:04.000-05:00
diff --git a/cores/arduino/SERCOM.cpp b/cores/arduino/SERCOM.cpp
@@ -175,7 +175,7 @@ int SERCOM::writeDataUART(uint8_t data)
 
 void SERCOM::enableDataRegisterEmptyInterruptUART()
 {
-  sercom->USART.INTENSET.reg |= SERCOM_USART_INTENSET_DRE;
+  sercom->USART.INTENSET.reg = SERCOM_USART_INTENSET_DRE;
 }
 
 void SERCOM::disableDataRegisterEmptyInterruptUART()

Original file line number	Diff line number	Diff line change
`@@ -175,7 +175,7 @@ int SERCOM::writeDataUART(uint8_t data)`
`175`	`175`
`176`	`176`	`void SERCOM::enableDataRegisterEmptyInterruptUART()`
`177`	`177`	`{`
`178`		`- sercom->USART.INTENSET.reg \|= SERCOM_USART_INTENSET_DRE;`
	`178`	`+ sercom->USART.INTENSET.reg = SERCOM_USART_INTENSET_DRE;`
`179`	`179`	`}`
`180`	`180`
`181`	`181`	`void SERCOM::disableDataRegisterEmptyInterruptUART()`