flm01/mote/v2/avr/buffer.c

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//
// buffer.c : Multipurpose byte buffer structure and methods
//
// Copyright (c) 2001 Pascal Stang
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
// $Id$
#include "buffer.h"
#include "global.h"
#include "avr/io.h"
#ifndef CRITICAL_SECTION_START
#define CRITICAL_SECTION_START unsigned char _sreg = SREG; cli()
#define CRITICAL_SECTION_END SREG = _sreg
#endif
// global variables
// initialization
void bufferInit(cBuffer* buffer, unsigned char *start, unsigned short size)
{
// begin critical section
CRITICAL_SECTION_START;
// set start pointer of the buffer
buffer->dataptr = start;
buffer->size = size;
// initialize index and length
buffer->dataindex = 0;
buffer->datalength = 0;
// end critical section
CRITICAL_SECTION_END;
}
// access routines
unsigned char bufferGetFromFront(cBuffer* buffer)
{
unsigned char data = 0;
// begin critical section
CRITICAL_SECTION_START;
// check to see if there's data in the buffer
if(buffer->datalength)
{
// get the first character from buffer
data = buffer->dataptr[buffer->dataindex];
// move index down and decrement length
buffer->dataindex++;
if(buffer->dataindex >= buffer->size)
{
buffer->dataindex -= buffer->size;
}
buffer->datalength--;
}
// end critical section
CRITICAL_SECTION_END;
// return
return data;
}
void bufferDumpFromFront(cBuffer* buffer, unsigned short numbytes)
{
// begin critical section
CRITICAL_SECTION_START;
// dump numbytes from the front of the buffer
// are we dumping less than the entire buffer?
if(numbytes < buffer->datalength)
{
// move index down by numbytes and decrement length by numbytes
buffer->dataindex += numbytes;
if(buffer->dataindex >= buffer->size)
{
buffer->dataindex -= buffer->size;
}
buffer->datalength -= numbytes;
}
else
{
// flush the whole buffer
buffer->datalength = 0;
}
// end critical section
CRITICAL_SECTION_END;
}
unsigned char bufferGetAtIndex(cBuffer* buffer, unsigned short index)
{
// begin critical section
CRITICAL_SECTION_START;
// return character at index in buffer
unsigned char data = buffer->dataptr[(buffer->dataindex+index)%(buffer->size)];
// end critical section
CRITICAL_SECTION_END;
return data;
}
unsigned char bufferAddToEnd(cBuffer* buffer, unsigned char data)
{
// begin critical section
CRITICAL_SECTION_START;
// make sure the buffer has room
if(buffer->datalength < buffer->size)
{
// save data byte at end of buffer
buffer->dataptr[(buffer->dataindex + buffer->datalength) % buffer->size] = data;
// increment the length
buffer->datalength++;
// end critical section
CRITICAL_SECTION_END;
// return success
return -1;
}
// end critical section
CRITICAL_SECTION_END;
// return failure
return 0;
}
unsigned short bufferIsNotFull(cBuffer* buffer)
{
// begin critical section
CRITICAL_SECTION_START;
// check to see if the buffer has room
// return true if there is room
unsigned short bytesleft = (buffer->size - buffer->datalength);
// end critical section
CRITICAL_SECTION_END;
return bytesleft;
}
void bufferFlush(cBuffer* buffer)
{
// begin critical section
CRITICAL_SECTION_START;
// flush contents of the buffer
buffer->datalength = 0;
// end critical section
CRITICAL_SECTION_END;
}