From d5ab80c69a75ba4244d93e4146fbdd8f1e6a948d Mon Sep 17 00:00:00 2001
From: "Dirk O. Kaar" <dok@dok-net.net>
Date: Thu, 19 Dec 2019 13:31:19 +0100
Subject: [PATCH 1/3] API compatibility to AVR, ESP8266, et al

---
 cores/esp32/HardwareSerial.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/cores/esp32/HardwareSerial.h b/cores/esp32/HardwareSerial.h
index 7d9f26d2fae..6b001679467 100644
--- a/cores/esp32/HardwareSerial.h
+++ b/cores/esp32/HardwareSerial.h
@@ -66,6 +66,10 @@ class HardwareSerial: public Stream
     void flush( bool txOnly);
     size_t write(uint8_t);
     size_t write(const uint8_t *buffer, size_t size);
+    inline size_t write(const char * buffer, size_t size)
+    {
+        return write((uint8_t*) buffer, size);
+    }
 
     inline size_t write(const char * s)
     {

From 69126cc6a200dd3035cb28b1e08656890b9970d9 Mon Sep 17 00:00:00 2001
From: "Dirk O. Kaar" <dok@dok-net.net>
Date: Thu, 19 Dec 2019 14:12:43 +0100
Subject: [PATCH 2/3] Add non-blocking HardwareSerial::read(buffer, size)
 extension (ESP8266 portability)

---
 cores/esp32/HardwareSerial.cpp | 18 ++++++++++++++++++
 cores/esp32/HardwareSerial.h   |  6 +++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/cores/esp32/HardwareSerial.cpp b/cores/esp32/HardwareSerial.cpp
index 860c2c0f604..3619f4bc17b 100644
--- a/cores/esp32/HardwareSerial.cpp
+++ b/cores/esp32/HardwareSerial.cpp
@@ -131,6 +131,24 @@ int HardwareSerial::read(void)
     return -1;
 }
 
+// read characters into buffer
+// terminates if size characters have been read, or no further are pending
+// returns the number of characters placed in the buffer
+// the buffer is NOT null terminated.
+size_t HardwareSerial::read(uint8_t *buffer, size_t size)
+{
+    size_t count = 0;
+    while(count < size) {
+        int c = read();
+        if(c < 0) {
+            break;
+        }
+        *buffer++ = (char) c;
+        count++;
+    }
+    return count;
+}
+
 void HardwareSerial::flush(void)
 {
     uartFlush(_uart);
diff --git a/cores/esp32/HardwareSerial.h b/cores/esp32/HardwareSerial.h
index 6b001679467..820476748da 100644
--- a/cores/esp32/HardwareSerial.h
+++ b/cores/esp32/HardwareSerial.h
@@ -62,6 +62,11 @@ class HardwareSerial: public Stream
     int availableForWrite(void);
     int peek(void);
     int read(void);
+    size_t read(uint8_t *buffer, size_t size);
+    inline size_t read(char * buffer, size_t size)
+    {
+        return read((uint8_t*) buffer, size);
+    }
     void flush(void);
     void flush( bool txOnly);
     size_t write(uint8_t);
@@ -70,7 +75,6 @@ class HardwareSerial: public Stream
     {
         return write((uint8_t*) buffer, size);
     }
-
     inline size_t write(const char * s)
     {
         return write((uint8_t*) s, strlen(s));

From 78da3ffdc0d17349ef680cd564a0dbc587a31d19 Mon Sep 17 00:00:00 2001
From: "Dirk O. Kaar" <dok@dok-net.net>
Date: Thu, 19 Dec 2019 14:42:21 +0100
Subject: [PATCH 3/3] Refactor for fewer indirect calls.

---
 cores/esp32/HardwareSerial.cpp | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/cores/esp32/HardwareSerial.cpp b/cores/esp32/HardwareSerial.cpp
index 3619f4bc17b..be80ca27d1d 100644
--- a/cores/esp32/HardwareSerial.cpp
+++ b/cores/esp32/HardwareSerial.cpp
@@ -137,13 +137,13 @@ int HardwareSerial::read(void)
 // the buffer is NOT null terminated.
 size_t HardwareSerial::read(uint8_t *buffer, size_t size)
 {
+    size_t avail = available();
+    if (size < avail) {
+        avail = size;
+    }
     size_t count = 0;
-    while(count < size) {
-        int c = read();
-        if(c < 0) {
-            break;
-        }
-        *buffer++ = (char) c;
+    while(count < avail) {
+        *buffer++ = uartRead(_uart);
         count++;
     }
     return count;