From 2f9d2f0fffc958bbaff7dfcf9e0412dbd254f6f4 Mon Sep 17 00:00:00 2001
From: Martino Facchin <m.facchin@arduino.cc>
Date: Mon, 10 May 2021 17:17:31 +0200
Subject: [PATCH 1/3] USBSerial: fix available() return size

---
 cores/arduino/USB/PluggableUSBSerial.h | 2 +-
 cores/arduino/USB/USBSerial.cpp        | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/cores/arduino/USB/PluggableUSBSerial.h b/cores/arduino/USB/PluggableUSBSerial.h
index 31d2e8bf7..a44e63fb7 100644
--- a/cores/arduino/USB/PluggableUSBSerial.h
+++ b/cores/arduino/USB/PluggableUSBSerial.h
@@ -115,7 +115,7 @@ class USBSerial: public USBCDC, public ::mbed::Stream, public HardwareSerial {
     *
     * @returns the number of bytes available
     */
-    uint8_t _available();
+    uint32_t _available();
 
     /**
     * Check if the terminal is connected.
diff --git a/cores/arduino/USB/USBSerial.cpp b/cores/arduino/USB/USBSerial.cpp
index 60ebdda4a..108697ef9 100644
--- a/cores/arduino/USB/USBSerial.cpp
+++ b/cores/arduino/USB/USBSerial.cpp
@@ -104,13 +104,13 @@ void USBSerial::data_rx()
     }
 }
 
-uint8_t USBSerial::_available()
+uint32_t USBSerial::_available()
 {
     USBCDC::lock();
 
-    uint8_t size = 0;
+    uint32_t size = 0;
     if (!_rx_in_progress) {
-        size = _rx_size > 0xFF ? 0xFF : _rx_size;
+        size = _rx_size > CDC_MAX_PACKET_SIZE ? CDC_MAX_PACKET_SIZE : _rx_size;
     }
 
     USBCDC::unlock();

From 5f9d84f7b7560420053ac68fe0227749e64ef8be Mon Sep 17 00:00:00 2001
From: Martino Facchin <m.facchin@arduino.cc>
Date: Mon, 10 May 2021 17:18:12 +0200
Subject: [PATCH 2/3] USBSerial: improve 1200bps reset routine

---
 cores/arduino/USB/PluggableUSBSerial.h |  2 +-
 cores/arduino/USB/USBSerial.cpp        | 11 +++++++----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/cores/arduino/USB/PluggableUSBSerial.h b/cores/arduino/USB/PluggableUSBSerial.h
index a44e63fb7..c7aa7ade4 100644
--- a/cores/arduino/USB/PluggableUSBSerial.h
+++ b/cores/arduino/USB/PluggableUSBSerial.h
@@ -294,7 +294,7 @@ class USBSerial: public USBCDC, public ::mbed::Stream, public HardwareSerial {
 
 private:
     RingBufferN<256> rx_buffer;
-    rtos::Thread t;
+    rtos::Thread* t;
     int _baud, _bits, _parity, _stop;
 
     void onInterrupt() {
diff --git a/cores/arduino/USB/USBSerial.cpp b/cores/arduino/USB/USBSerial.cpp
index 108697ef9..d46e8b24d 100644
--- a/cores/arduino/USB/USBSerial.cpp
+++ b/cores/arduino/USB/USBSerial.cpp
@@ -26,7 +26,11 @@
 
 using namespace arduino;
 
+static rtos::EventFlags event;
+
 static void waitForPortClose() {
+
+    event.wait_any(0xFF);
     // wait for DTR be 0 (port closed) and timeout to be over
     long start = millis();
     static const int WAIT_TIMEOUT = 200;
@@ -37,11 +41,9 @@ static void waitForPortClose() {
     _ontouch1200bps_();
 }
 
-static events::EventQueue queue(2 * EVENTS_EVENT_SIZE);
-
 void usbPortChanged(int baud, int bits, int parity, int stop) {
     if (baud == 1200) {
-        queue.call(waitForPortClose);
+        event.set(1);
     }
 }
 
@@ -68,7 +70,8 @@ USBSerial::~USBSerial()
 void USBSerial::begin(unsigned long) {
     this->attach(usbPortChanged);
     this->attach(::mbed::callback(this, &USBSerial::onInterrupt));
-    t.start(callback(&queue, &::events::EventQueue::dispatch_forever));
+    t = new rtos::Thread(osPriorityNormal, 256, nullptr, "USBevt");
+    t->start(waitForPortClose);
 }
 
 int USBSerial::_putc(int c)

From 91b5fb6d31ace2891a6f545cdf1debf4439100fd Mon Sep 17 00:00:00 2001
From: Martino Facchin <m.facchin@arduino.cc>
Date: Mon, 10 May 2021 17:18:03 +0200
Subject: [PATCH 3/3] USBSerial: speedup by using non blocking read

---
 cores/arduino/USB/PluggableUSBSerial.h | 12 ++++++++++--
 cores/arduino/USB/USBSerial.cpp        |  1 +
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/cores/arduino/USB/PluggableUSBSerial.h b/cores/arduino/USB/PluggableUSBSerial.h
index c7aa7ade4..505999c99 100644
--- a/cores/arduino/USB/PluggableUSBSerial.h
+++ b/cores/arduino/USB/PluggableUSBSerial.h
@@ -298,8 +298,16 @@ class USBSerial: public USBCDC, public ::mbed::Stream, public HardwareSerial {
     int _baud, _bits, _parity, _stop;
 
     void onInterrupt() {
-        while (rx_buffer.availableForStore() && _available()) {
-            rx_buffer.store_char(_getc());
+        uint8_t buf[256];
+        int howMany = _available();
+        uint32_t toRead;
+        if (howMany > rx_buffer.availableForStore()) {
+            howMany = rx_buffer.availableForStore();
+        }
+        receive_nb(buf, howMany, &toRead);
+        while (rx_buffer.availableForStore() && toRead > 0) {
+            rx_buffer.store_char(buf[howMany-toRead]);
+            toRead --;
         }
     }
 
diff --git a/cores/arduino/USB/USBSerial.cpp b/cores/arduino/USB/USBSerial.cpp
index d46e8b24d..4a756ba45 100644
--- a/cores/arduino/USB/USBSerial.cpp
+++ b/cores/arduino/USB/USBSerial.cpp
@@ -72,6 +72,7 @@ void USBSerial::begin(unsigned long) {
     this->attach(::mbed::callback(this, &USBSerial::onInterrupt));
     t = new rtos::Thread(osPriorityNormal, 256, nullptr, "USBevt");
     t->start(waitForPortClose);
+    onInterrupt();
 }
 
 int USBSerial::_putc(int c)