Fix UART wrong ::available() during wraparound (#739)

earlephilhower · web-flow · commit cabb06d495cb · 2022-08-06T09:38:16.000-07:00
Fixes #735 . Thanks to @ Haggarman for the find and fix.
diff --git a/cores/rp2040/SerialUART.cpp b/cores/rp2040/SerialUART.cpp
@@ -292,7 +292,7 @@ int SerialUART::available() {
     } else {
         _pumpFIFO();
     }
-    return (_writer - _reader) % _fifoSize;
+    return (_fifoSize + _writer - _reader) % _fifoSize;
 }
 
 int SerialUART::availableForWrite() {

Original file line number	Diff line number	Diff line change
`@@ -292,7 +292,7 @@ int SerialUART::available() {`
`292`	`292`	`} else {`
`293`	`293`	`_pumpFIFO();`
`294`	`294`	`}`
`295`		`- return (_writer - _reader) % _fifoSize;`
	`295`	`+ return (_fifoSize + _writer - _reader) % _fifoSize;`
`296`	`296`	`}`
`297`	`297`
`298`	`298`	`int SerialUART::availableForWrite() {`