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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
Modified 28 September 2010 by Mark Sproul
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include "wiring.h"
#include "wiring_private.h"
// this next line disables the entire HardwareSerial.cpp,
// this is so I can support Attiny series and any other chip without a uart
#if defined(UBRRH) || defined(UBRR0H) || defined(UBRR1H) || defined(UBRR2H) || defined(UBRR3H)
#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 };
inline void store_char(unsigned char c, ring_buffer *rx_buffer)
{
int i = (unsigned int)(rx_buffer->head + 1) & (RX_BUFFER_SIZE -1);
// 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;
}
}
// fixed by Mark Sproul this is on the 644/644p
//SIGNAL(SIG_USART_RECV)
SIGNAL(USART0_RX_vect)
{
unsigned char c = UDR0;
store_char(c, &rx_buffer);
}
// 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 baud)
{
uint16_t baud_setting;
bool use_u2x = true;
#if F_CPU == 16000000UL
// hardcoded exception for compatibility with the bootloader shipped
// with the Duemilanove and previous boards and the firmware on the 8U2
// on the Uno and Mega 2560.
if (baud == 57600) {
use_u2x = false;
}
#endif
if (use_u2x) {
*_ucsra = 1 << _u2x;
baud_setting = (F_CPU / 4 / baud - 1) / 2;
} else {
*_ucsra = 0;
baud_setting = (F_CPU / 8 / baud - 1) / 2;
}
// assign the baud_setting, a.k.a. ubbr (USART Baud Rate Register)
*_ubrrh = baud_setting >> 8;
*_ubrrl = baud_setting;
sbi(*_ucsrb, _rxen);
sbi(*_ucsrb, _txen);
sbi(*_ucsrb, _rxcie);
}
void HardwareSerial::end()
{
cbi(*_ucsrb, _rxen);
cbi(*_ucsrb, _txen);
cbi(*_ucsrb, _rxcie);
}
int HardwareSerial::available(void)
{
return (unsigned int)(RX_BUFFER_SIZE + _rx_buffer->head - _rx_buffer->tail) & (RX_BUFFER_SIZE-1);
}
int HardwareSerial::peek(void)
{
if (_rx_buffer->head == _rx_buffer->tail) {
return -1;
} else {
return _rx_buffer->buffer[_rx_buffer->tail];
}
}
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 = (unsigned int)(_rx_buffer->tail + 1) & (RX_BUFFER_SIZE-1);
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;
}
//
// Drakelive 2012-09-04
//
#if ARDUINO >= 100
size_t HardwareSerial::write(uint8_t c)
{
while (!((*_ucsra) & (1 << _udre)))
;
*_udr = c;
}
#else
void HardwareSerial::write(uint8_t c)
{
while (!((*_ucsra) & (1 << _udre)))
;
*_udr = c;
}
#endif
// Drakelive 2012-09-04
// Preinstantiate Objects //////////////////////////////////////////////////////
HardwareSerial Serial(&rx_buffer, &UBRR0H, &UBRR0L, &UCSR0A, &UCSR0B, &UDR0, RXEN0, TXEN0, RXCIE0, UDRE0, U2X0);
#endif // whole file