154 lines
4.0 KiB
C
154 lines
4.0 KiB
C
//
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// buffer.c : Multipurpose byte buffer structure and methods
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//
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// Copyright (c) 2001 Pascal Stang
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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 "buffer.h"
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#include "global.h"
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#include "avr/io.h"
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#ifndef CRITICAL_SECTION_START
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#define CRITICAL_SECTION_START unsigned char _sreg = SREG; cli()
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#define CRITICAL_SECTION_END SREG = _sreg
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#endif
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// global variables
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// initialization
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void bufferInit(cBuffer* buffer, unsigned char *start, unsigned short size)
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{
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// begin critical section
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CRITICAL_SECTION_START;
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// set start pointer of the buffer
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buffer->dataptr = start;
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buffer->size = size;
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// initialize index and length
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buffer->dataindex = 0;
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buffer->datalength = 0;
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// end critical section
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CRITICAL_SECTION_END;
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}
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// access routines
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unsigned char bufferGetFromFront(cBuffer* buffer)
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{
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unsigned char data = 0;
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// begin critical section
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CRITICAL_SECTION_START;
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// check to see if there's data in the buffer
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if(buffer->datalength)
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{
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// get the first character from buffer
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data = buffer->dataptr[buffer->dataindex];
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// move index down and decrement length
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buffer->dataindex++;
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if(buffer->dataindex >= buffer->size)
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{
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buffer->dataindex -= buffer->size;
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}
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buffer->datalength--;
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}
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// end critical section
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CRITICAL_SECTION_END;
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// return
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return data;
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}
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void bufferDumpFromFront(cBuffer* buffer, unsigned short numbytes)
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{
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// begin critical section
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CRITICAL_SECTION_START;
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// dump numbytes from the front of the buffer
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// are we dumping less than the entire buffer?
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if(numbytes < buffer->datalength)
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{
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// move index down by numbytes and decrement length by numbytes
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buffer->dataindex += numbytes;
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if(buffer->dataindex >= buffer->size)
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{
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buffer->dataindex -= buffer->size;
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}
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buffer->datalength -= numbytes;
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}
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else
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{
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// flush the whole buffer
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buffer->datalength = 0;
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}
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// end critical section
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CRITICAL_SECTION_END;
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}
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unsigned char bufferGetAtIndex(cBuffer* buffer, unsigned short index)
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{
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// begin critical section
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CRITICAL_SECTION_START;
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// return character at index in buffer
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unsigned char data = buffer->dataptr[(buffer->dataindex+index)%(buffer->size)];
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// end critical section
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CRITICAL_SECTION_END;
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return data;
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}
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unsigned char bufferAddToEnd(cBuffer* buffer, unsigned char data)
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{
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// begin critical section
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CRITICAL_SECTION_START;
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// make sure the buffer has room
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if(buffer->datalength < buffer->size)
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{
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// save data byte at end of buffer
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buffer->dataptr[(buffer->dataindex + buffer->datalength) % buffer->size] = data;
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// increment the length
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buffer->datalength++;
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// end critical section
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CRITICAL_SECTION_END;
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// return success
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return -1;
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}
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// end critical section
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CRITICAL_SECTION_END;
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// return failure
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return 0;
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}
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unsigned short bufferIsNotFull(cBuffer* buffer)
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{
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// begin critical section
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CRITICAL_SECTION_START;
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// check to see if the buffer has room
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// return true if there is room
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unsigned short bytesleft = (buffer->size - buffer->datalength);
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// end critical section
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CRITICAL_SECTION_END;
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return bytesleft;
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}
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void bufferFlush(cBuffer* buffer)
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{
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// begin critical section
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CRITICAL_SECTION_START;
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// flush contents of the buffer
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buffer->datalength = 0;
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// end critical section
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CRITICAL_SECTION_END;
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}
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