From 5962f155f70a5c67d14280d1b178f5197fb00df4 Mon Sep 17 00:00:00 2001 From: Paul Brook Date: Fri, 21 Mar 2014 18:43:19 +0000 Subject: Improve CDC read code Read CDC data from USB FIFO on demand instead of in ISR. Remove superfluous ring buffer. Signed-off-by: Paul Brook --- cores/arduino/CDC.cpp | 66 ++++++++++----------------------------------------- 1 file changed, 12 insertions(+), 54 deletions(-) (limited to 'cores/arduino/CDC.cpp') diff --git a/cores/arduino/CDC.cpp b/cores/arduino/CDC.cpp index fb0c0e0..3dbf15d 100644 --- a/cores/arduino/CDC.cpp +++ b/cores/arduino/CDC.cpp @@ -23,21 +23,6 @@ #if defined(USBCON) #ifdef CDC_ENABLED -#if (RAMEND < 1000) -#define SERIAL_BUFFER_SIZE 16 -#else -#define SERIAL_BUFFER_SIZE 64 -#endif - -struct ring_buffer -{ - unsigned char buffer[SERIAL_BUFFER_SIZE]; - volatile int head; - volatile int tail; -}; - -ring_buffer cdc_rx_buffer = { { 0 }, 0, 0}; - typedef struct { u32 dwDTERate; @@ -129,7 +114,6 @@ bool WEAK CDC_Setup(Setup& setup) } -int _serialPeek = -1; void Serial_::begin(unsigned long baud_count) { } @@ -142,55 +126,29 @@ void Serial_::end(void) { } -void Serial_::accept(void) -{ - ring_buffer *buffer = &cdc_rx_buffer; - int i = (unsigned int)(buffer->head+1) % SERIAL_BUFFER_SIZE; - - // if we should be storing the received character into the location - // just before the tail (meaning that the head would advance to the - // current location of the tail), we're about to overflow the buffer - // and so we don't write the character or advance the head. - - // while we have room to store a byte - while (i != buffer->tail) { - int c = USB_Recv(CDC_RX); - if (c == -1) - break; // no more data - buffer->buffer[buffer->head] = c; - buffer->head = i; - - i = (unsigned int)(buffer->head+1) % SERIAL_BUFFER_SIZE; - } -} - int Serial_::available(void) { - ring_buffer *buffer = &cdc_rx_buffer; - return (unsigned int)(SERIAL_BUFFER_SIZE + buffer->head - buffer->tail) % SERIAL_BUFFER_SIZE; + if (peek_buffer >= 0) { + return 1; + } + return USB_Available(CDC_RX); } int Serial_::peek(void) { - ring_buffer *buffer = &cdc_rx_buffer; - if (buffer->head == buffer->tail) { - return -1; - } else { - return buffer->buffer[buffer->tail]; - } + if (peek_buffer < 0) + peek_buffer = USB_Recv(CDC_RX); + return peek_buffer; } int Serial_::read(void) { - ring_buffer *buffer = &cdc_rx_buffer; - // if the head isn't ahead of the tail, we don't have any characters - if (buffer->head == buffer->tail) { - return -1; - } else { - unsigned char c = buffer->buffer[buffer->tail]; - buffer->tail = (unsigned int)(buffer->tail + 1) % SERIAL_BUFFER_SIZE; + if (peek_buffer >= 0) { + int c = peek_buffer; + peek_buffer = -1; return c; - } + } + return USB_Recv(CDC_RX); } void Serial_::flush(void) -- cgit v1.2.3-18-g5258