298 lines
7.0 KiB
C
298 lines
7.0 KiB
C
//
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// uart.c : UART driver with buffer support
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//
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// Copyright (c) 2000-2002 Pascal Stang
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// 2010 flukso.net
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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//
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// $Id$
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include "buffer.h"
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#include "uart.h"
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// UART global variables
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// flag variables
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volatile u08 uartReadyTx; ///< uartReadyTx flag
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volatile u08 uartBufferedTx; ///< uartBufferedTx flag
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// receive and transmit buffers
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cBuffer uartRxBuffer; ///< uart receive buffer
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cBuffer uartTxBuffer; ///< uart transmit buffer
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unsigned short uartRxOverflow; ///< receive overflow counter
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#ifndef UART_BUFFERS_EXTERNAL_RAM
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// using internal ram,
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// automatically allocate space in ram for each buffer
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static char uartRxData[UART_RX_BUFFER_SIZE];
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static char uartTxData[UART_TX_BUFFER_SIZE];
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#endif
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typedef void (*voidFuncPtru08)(unsigned char);
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volatile static voidFuncPtru08 UartRxFunc;
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// enable and initialize the uart
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void uartInit(void)
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{
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// initialize the buffers
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uartInitBuffers();
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// initialize user receive handler
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UartRxFunc = 0;
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// enable RxD/TxD and interrupts
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outb(UCR, BV(RXCIE)|BV(RXEN)|BV(TXEN));
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// set default baud rate
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uartSetBaudRate(UART_DEFAULT_BAUD_RATE);
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// initialize states
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uartReadyTx = TRUE;
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uartBufferedTx = FALSE;
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// clear overflow count
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uartRxOverflow = 0;
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// enable interrupts
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sei();
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}
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// create and initialize the uart transmit and receive buffers
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void uartInitBuffers(void)
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{
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#ifndef UART_BUFFERS_EXTERNAL_RAM
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// initialize the UART receive buffer
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bufferInit(&uartRxBuffer, (u08*) uartRxData, UART_RX_BUFFER_SIZE);
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// initialize the UART transmit buffer
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bufferInit(&uartTxBuffer, (u08*) uartTxData, UART_TX_BUFFER_SIZE);
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#else
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// initialize the UART receive buffer
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bufferInit(&uartRxBuffer, (u08*) UART_RX_BUFFER_ADDR, UART_RX_BUFFER_SIZE);
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// initialize the UART transmit buffer
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bufferInit(&uartTxBuffer, (u08*) UART_TX_BUFFER_ADDR, UART_TX_BUFFER_SIZE);
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#endif
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}
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// redirects received data to a user function
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void uartSetRxHandler(void (*rx_func)(unsigned char c))
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{
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// set the receive interrupt to run the supplied user function
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UartRxFunc = rx_func;
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}
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// set the uart baud rate
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void uartSetBaudRate(u32 baudrate)
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{
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// calculate division factor for requested baud rate, and set it
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u16 bauddiv = ((F_CPU+(baudrate*8L))/(baudrate*16L)-1);
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outb(UBRRL, bauddiv);
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#ifdef UBRRH
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outb(UBRRH, bauddiv>>8);
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#endif
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}
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// returns the receive buffer structure
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cBuffer* uartGetRxBuffer(void)
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{
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// return rx buffer pointer
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return &uartRxBuffer;
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}
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// returns the transmit buffer structure
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cBuffer* uartGetTxBuffer(void)
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{
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// return tx buffer pointer
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return &uartTxBuffer;
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}
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// transmits a byte over the uart
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void uartSendByte(u08 txData)
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{
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// wait for the transmitter to be ready
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while(!uartReadyTx);
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// send byte
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outb(UDR, txData);
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// set ready state to FALSE
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uartReadyTx = FALSE;
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}
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// gets a single byte from the uart receive buffer (getchar-style)
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int uartGetByte(void)
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{
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u08 c;
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if(uartReceiveByte(&c))
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return c;
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else
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return -1;
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}
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// gets a byte (if available) from the uart receive buffer
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u08 uartReceiveByte(u08* rxData)
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{
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// make sure we have a receive buffer
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if(uartRxBuffer.size)
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{
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// make sure we have data
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if(uartRxBuffer.datalength)
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{
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// get byte from beginning of buffer
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*rxData = bufferGetFromFront(&uartRxBuffer);
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return TRUE;
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}
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else
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{
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// no data
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return FALSE;
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}
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}
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else
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{
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// no buffer
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return FALSE;
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}
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}
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// flush all data out of the receive buffer
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void uartFlushReceiveBuffer(void)
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{
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// flush all data from receive buffer
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//bufferFlush(&uartRxBuffer);
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// same effect as above
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uartRxBuffer.datalength = 0;
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}
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// return true if uart receive buffer is empty
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u08 uartReceiveBufferIsEmpty(void)
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{
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if(uartRxBuffer.datalength == 0)
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{
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return TRUE;
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}
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else
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{
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return FALSE;
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}
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}
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// add byte to end of uart Tx buffer
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u08 uartAddToTxBuffer(u08 data)
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{
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u08 status;
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// add data byte to the end of the tx buffer
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status = bufferAddToEnd(&uartTxBuffer, data);
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// turn on buffered transmit
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uartBufferedTx = TRUE;
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// enable UDRIE0 interrupt
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UCR |= 1<<UDRIE0;
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return status;
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}
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// start transmission of the current uart Tx buffer contents
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void uartSendTxBuffer(void)
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{
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// turn on buffered transmit
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uartBufferedTx = TRUE;
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// send the first byte to get things going by interrupts
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uartSendByte(bufferGetFromFront(&uartTxBuffer));
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}
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/*
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// transmit nBytes from buffer out the uart
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u08 uartSendBuffer(char *buffer, u16 nBytes)
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{
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register u08 first;
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register u16 i;
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// check if there's space (and that we have any bytes to send at all)
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if((uartTxBuffer.datalength + nBytes < uartTxBuffer.size) && nBytes)
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{
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// grab first character
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first = *buffer++;
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// copy user buffer to uart transmit buffer
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for(i = 0; i < nBytes-1; i++)
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{
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// put data bytes at end of buffer
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bufferAddToEnd(&uartTxBuffer, *buffer++);
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}
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// send the first byte to get things going by interrupts
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uartBufferedTx = TRUE;
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uartSendByte(first);
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// return success
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return TRUE;
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}
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else
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{
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// return failure
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return FALSE;
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}
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}
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*/
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// UART Transmit Complete Interrupt Handler
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UART_INTERRUPT_HANDLER(SIG_UART_DATA)
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{
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// check if buffered tx is enabled
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if(uartBufferedTx)
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{
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// check if there's data left in the buffer
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if(uartTxBuffer.datalength)
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{
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// send byte from top of buffer
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outb(UDR, bufferGetFromFront(&uartTxBuffer));
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}
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else
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{
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// no data left
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uartBufferedTx = FALSE;
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// return to ready state
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uartReadyTx = TRUE;
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// disable TXCIE0 interrupt
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UCR &= ~(1<<UDRIE0);
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}
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}
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else
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{
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// we're using single-byte tx mode
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// indicate transmit complete, back to ready
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uartReadyTx = TRUE;
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}
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}
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// UART Receive Complete Interrupt Handler
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UART_INTERRUPT_HANDLER(SIG_UART_RECV)
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{
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u08 c;
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// get received char
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c = inb(UDR);
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// if there's a user function to handle this receive event
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if(UartRxFunc)
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{
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// call it and pass the received data
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UartRxFunc(c);
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}
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else
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{
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// otherwise do default processing
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// put received char in buffer
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// check if there's space
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if( !bufferAddToEnd(&uartRxBuffer, c) )
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{
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// no space in buffer
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// count overflow
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uartRxOverflow++;
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}
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}
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}
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