From 1e2b0ffd14789c325362159439f3f3b00db1f48d Mon Sep 17 00:00:00 2001
From: LDP-Soft <117711872+LDP-Soft@users.noreply.github.com>
Date: Tue, 8 Nov 2022 00:37:47 -0600
Subject: [PATCH 1/2] Update HardwareSerial.h

---
 cores/arduino/HardwareSerial.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/cores/arduino/HardwareSerial.h b/cores/arduino/HardwareSerial.h
index 6ff29d0b9..ee946b1b1 100644
--- a/cores/arduino/HardwareSerial.h
+++ b/cores/arduino/HardwareSerial.h
@@ -123,6 +123,7 @@ class HardwareSerial : public Stream
     void end();
     virtual int available(void);
     virtual int peek(void);
+    virtual int peekLast(void);
     virtual int read(void);
     virtual int availableForWrite(void);
     virtual void flush(void);

From d8a904ff0cda8679171e390a0199b31e88b3a0f7 Mon Sep 17 00:00:00 2001
From: LDP-Soft <117711872+LDP-Soft@users.noreply.github.com>
Date: Tue, 8 Nov 2022 00:38:54 -0600
Subject: [PATCH 2/2] Update HardwareSerial.cpp

---
 cores/arduino/HardwareSerial.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/cores/arduino/HardwareSerial.cpp b/cores/arduino/HardwareSerial.cpp
index 561127f9f..4606db06b 100644
--- a/cores/arduino/HardwareSerial.cpp
+++ b/cores/arduino/HardwareSerial.cpp
@@ -177,6 +177,11 @@ int HardwareSerial::peek(void)
   }
 }
 
+int HardwareSerial::peekLast(void)
+{
+  return _rx_buffer_head==_rx_buffer_tail ? -1 : _rx_buffer[(SERIAL_RX_BUFFER_SIZE+_rx_buffer_tail-1)%SERIAL_RX_BUFFER_SIZE];
+}
+
 int HardwareSerial::read(void)
 {
   // if the head isn't ahead of the tail, we don't have any characters