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/*
HardwareSerial.cpp - Hardware serial library for Wiring
Copyright (c) 2006 Nicholas Zambetti. All right reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
Modified 23 November 2006 by David A. Mellis
*/
#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include "wiring.h"
#include "wiring_private.h"
#include "HardwareSerial.h"
// Define constants and variables for buffering incoming serial data. We're
// using a ring buffer (I think), in which rx_buffer_head is the index of the
// location to which to write the next incoming character and rx_buffer_tail
// is the index of the location from which to read.
#define RX_BUFFER_SIZE 128
struct ring_buffer {
unsigned char buffer[RX_BUFFER_SIZE];
int head;
int tail;
};
ring_buffer rx_buffer = { { 0 }, 0, 0 };
#if defined(__AVR_ATmega1280__)
ring_buffer rx_buffer1 = { { 0 }, 0, 0 };
ring_buffer rx_buffer2 = { { 0 }, 0, 0 };
ring_buffer rx_buffer3 = { { 0 }, 0, 0 };
#endif
inline void store_char(unsigned char c, ring_buffer *rx_buffer)
{
int i = (rx_buffer->head + 1) % RX_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.
if (i != rx_buffer->tail) {
rx_buffer->buffer[rx_buffer->head] = c;
rx_buffer->head = i;
}
}
#if defined(__AVR_ATmega1280__)
SIGNAL(SIG_USART0_RECV)
{
unsigned char c = UDR0;
store_char(c, &rx_buffer);
}
SIGNAL(SIG_USART1_RECV)
{
unsigned char c = UDR1;
store_char(c, &rx_buffer1);
}
SIGNAL(SIG_USART2_RECV)
{
unsigned char c = UDR2;
store_char(c, &rx_buffer2);
}
SIGNAL(SIG_USART3_RECV)
{
unsigned char c = UDR3;
store_char(c, &rx_buffer3);
}
#else
#if defined(__AVR_ATmega8__)
SIGNAL(SIG_UART_RECV)
#else
SIGNAL(USART_RX_vect)
#endif
{
#if defined(__AVR_ATmega8__)
unsigned char c = UDR;
#else
unsigned char c = UDR0;
#endif
store_char(c, &rx_buffer);
}
#endif
// Constructors ////////////////////////////////////////////////////////////////
HardwareSerial::HardwareSerial(ring_buffer *rx_buffer,
volatile uint8_t *ubrrh, volatile uint8_t *ubrrl,
volatile uint8_t *ucsra, volatile uint8_t *ucsrb,
volatile uint8_t *udr,
uint8_t rxen, uint8_t txen, uint8_t rxcie, uint8_t udre, uint8_t u2x)
{
_rx_buffer = rx_buffer;
_ubrrh = ubrrh;
_ubrrl = ubrrl;
_ucsra = ucsra;
_ucsrb = ucsrb;
_udr = udr;
_rxen = rxen;
_txen = txen;
_rxcie = rxcie;
_udre = udre;
_u2x = u2x;
}
// Public Methods //////////////////////////////////////////////////////////////
void HardwareSerial::begin(long speed)
{
*_ubrrh = ((F_CPU / 16 + speed / 2) / speed - 1) >> 8;
*_ubrrl = ((F_CPU / 16 + speed / 2) / speed - 1);
cbi(*_ucsra, _u2x);
sbi(*_ucsrb, _rxen);
sbi(*_ucsrb, _txen);
sbi(*_ucsrb, _rxcie);
}
uint8_t HardwareSerial::available(void)
{
return (RX_BUFFER_SIZE + _rx_buffer->head - _rx_buffer->tail) % RX_BUFFER_SIZE;
}
int HardwareSerial::read(void)
{
// if the head isn't ahead of the tail, we don't have any characters
if (_rx_buffer->head == _rx_buffer->tail) {
return -1;
} else {
unsigned char c = _rx_buffer->buffer[_rx_buffer->tail];
_rx_buffer->tail = (_rx_buffer->tail + 1) % RX_BUFFER_SIZE;
return c;
}
}
void HardwareSerial::flush()
{
// don't reverse this or there may be problems if the RX interrupt
// occurs after reading the value of rx_buffer_head but before writing
// the value to rx_buffer_tail; the previous value of rx_buffer_head
// may be written to rx_buffer_tail, making it appear as if the buffer
// don't reverse this or there may be problems if the RX interrupt
// occurs after reading the value of rx_buffer_head but before writing
// the value to rx_buffer_tail; the previous value of rx_buffer_head
// may be written to rx_buffer_tail, making it appear as if the buffer
// were full, not empty.
_rx_buffer->head = _rx_buffer->tail;
}
void HardwareSerial::write(uint8_t c)
{
while (!((*_ucsra) & (1 << _udre)))
;
*_udr = c;
}
// Preinstantiate Objects //////////////////////////////////////////////////////
#if defined(__AVR_ATmega8__)
HardwareSerial Serial(&rx_buffer, &UBRRH, &UBRRL, &UCSRA, &UCSRB, &UDR, RXEN, TXEN, RXCIE, UDRE, U2X);
#else
HardwareSerial Serial(&rx_buffer, &UBRR0H, &UBRR0L, &UCSR0A, &UCSR0B, &UDR0, RXEN0, TXEN0, RXCIE0, UDRE0, U2X0);
#endif
#if defined(__AVR_ATmega1280__)
HardwareSerial Serial1(&rx_buffer1, &UBRR1H, &UBRR1L, &UCSR1A, &UCSR1B, &UDR1, RXEN1, TXEN1, RXCIE1, UDRE1, U2X1);
HardwareSerial Serial2(&rx_buffer2, &UBRR2H, &UBRR2L, &UCSR2A, &UCSR2B, &UDR2, RXEN2, TXEN2, RXCIE2, UDRE2, U2X2);
HardwareSerial Serial3(&rx_buffer3, &UBRR3H, &UBRR3L, &UCSR3A, &UCSR3B, &UDR3, RXEN3, TXEN3, RXCIE3, UDRE3, U2X3);
#endif
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