From 19ae0eb4d437eff9efa54bb14de636006f94b13c Mon Sep 17 00:00:00 2001
From: Cristian Maglie <c.maglie@arduino.cc>
Date: Fri, 24 Jun 2016 15:59:57 +0200
Subject: [PATCH] USB-CDC: access to rx buffer is now ISR-protected
---
cores/arduino/USB/CDC.cpp | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/cores/arduino/USB/CDC.cpp b/cores/arduino/USB/CDC.cpp
index 6ae5e658..e6fc4a5b 100644
--- a/cores/arduino/USB/CDC.cpp
+++ b/cores/arduino/USB/CDC.cpp
@@ -214,24 +214,24 @@ int Serial_::read(void)
{
ring_buffer *buffer = &cdc_rx_buffer;
+ uint8_t enableInterrupts = ((__get_PRIMASK() & 0x1) == 0);
+ __disable_irq();
+
// if we have enough space enable OUT endpoint to receive more data
if (stalled && availableForStore() >= EPX_SIZE)
{
stalled = false;
usb.epOut(CDC_ENDPOINT_OUT);
}
- if (buffer->head == buffer->tail && !buffer->full)
- {
- return -1;
- }
- else
+ int c = -1;
+ if (buffer->head != buffer->tail || buffer->full)
{
- unsigned char c = buffer->buffer[buffer->tail];
+ c = buffer->buffer[buffer->tail];
buffer->tail = (uint32_t)(buffer->tail + 1) % CDC_SERIAL_BUFFER_SIZE;
buffer->full = false;
-
- return c;
}
+ if (enableInterrupts) __enable_irq();
+ return c;
}
void Serial_::flush(void)
--
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