Firmware/Marlin/wiring_serial.c
Erik van der Zalm 750f6c33e3 first commit
2011-08-12 22:28:35 +02:00

140 lines
4.1 KiB
C

/*
wiring_serial.c - serial functions.
Part of Arduino - http://www.arduino.cc/
Copyright (c) 2005-2006 David A. Mellis
Modified 29 January 2009, Marius Kintel for Sanguino - http://www.sanguino.cc/
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., 59 Temple Place, Suite 330,
Boston, MA 02111-1307 USA
$Id: wiring.c 248 2007-02-03 15:36:30Z mellis $
*/
#include "wiring_private.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
#define RX_BUFFER_MASK 0x7f
#if defined(__AVR_ATmega644P__)
unsigned char rx_buffer[2][RX_BUFFER_SIZE];
int rx_buffer_head[2] = {0, 0};
int rx_buffer_tail[2] = {0, 0};
#else
unsigned char rx_buffer[1][RX_BUFFER_SIZE];
int rx_buffer_head[1] = {0};
int rx_buffer_tail[1] = {0};
#endif
#define BEGIN_SERIAL(uart_, baud_) \
{ \
UBRR##uart_##H = ((F_CPU / 16 + baud / 2) / baud - 1) >> 8; \
UBRR##uart_##L = ((F_CPU / 16 + baud / 2) / baud - 1); \
\
/* reset config for UART */ \
UCSR##uart_##A = 0; \
UCSR##uart_##B = 0; \
UCSR##uart_##C = 0; \
\
/* enable rx and tx */ \
sbi(UCSR##uart_##B, RXEN##uart_);\
sbi(UCSR##uart_##B, TXEN##uart_);\
\
/* enable interrupt on complete reception of a byte */ \
sbi(UCSR##uart_##B, RXCIE##uart_); \
UCSR##uart_##C = _BV(UCSZ##uart_##1)|_BV(UCSZ##uart_##0); \
/* defaults to 8-bit, no parity, 1 stop bit */ \
}
void beginSerial(uint8_t uart, long baud)
{
if (uart == 0) BEGIN_SERIAL(0, baud)
#if defined(__AVR_ATmega644P__)
else BEGIN_SERIAL(1, baud)
#endif
}
#define SERIAL_WRITE(uart_, c_) \
while (!(UCSR##uart_##A & (1 << UDRE##uart_))) \
; \
UDR##uart_ = c
void serialWrite(uint8_t uart, unsigned char c)
{
if (uart == 0) {
SERIAL_WRITE(0, c);
}
#if defined(__AVR_ATmega644P__)
else {
SERIAL_WRITE(1, c);
}
#endif
}
int serialAvailable(uint8_t uart)
{
return (RX_BUFFER_SIZE + rx_buffer_head[uart] - rx_buffer_tail[uart]) & RX_BUFFER_MASK;
}
int serialRead(uint8_t uart)
{
// if the head isn't ahead of the tail, we don't have any characters
if (rx_buffer_head[uart] == rx_buffer_tail[uart]) {
return -1;
} else {
unsigned char c = rx_buffer[uart][rx_buffer_tail[uart]];
rx_buffer_tail[uart] = (rx_buffer_tail[uart] + 1) & RX_BUFFER_MASK;
return c;
}
}
void serialFlush(uint8_t uart)
{
// 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[uart] = rx_buffer_tail[uart];
}
#define UART_ISR(uart_) \
ISR(USART##uart_##_RX_vect) \
{ \
unsigned char c = UDR##uart_; \
\
int i = (rx_buffer_head[uart_] + 1) & RX_BUFFER_MASK; \
\
/* 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[uart_]) { \
rx_buffer[uart_][rx_buffer_head[uart_]] = c; \
rx_buffer_head[uart_] = i; \
} \
}
UART_ISR(0)
#if defined(__AVR_ATmega644P__)
UART_ISR(1)
#endif