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output.c
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output.c
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/*
* This file is part of dsptunnel.
*
* dsptunnel 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 3 of the License, or
* (at your option) any later version.
*
* dsptunnel 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 dsptunnel. If not, see <http://www.gnu.org/licenses/>.
*/
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <poll.h>
#include <limits.h>
#include "dsptunnel.h"
#include "fletcher.h"
#include "output.h"
#define DATABUFFERSIZE 2048
static unsigned char databuffer[DATABUFFERSIZE];
#define AUDIOBUFFERSIZE 1024*2
static short int audiobuffer[AUDIOBUFFERSIZE];
static int bufferpos;
static int audio_out( int dsp, short int left, short int right )
{
if( bufferpos >= AUDIOBUFFERSIZE )
{
if( write( dsp, audiobuffer, sizeof( short int ) * AUDIOBUFFERSIZE ) != sizeof( short int ) * AUDIOBUFFERSIZE )
{
perror( "audio_out: write" );
return 0;
}
bufferpos = 0;
}
audiobuffer[bufferpos++] = left;
audiobuffer[bufferpos++] = right;
return 1;
}
void *output_loop( void *inopts )
{
struct threadopts opts = *(struct threadopts *)inopts;
struct pollfd pollfd;
int i, j, k;
unsigned char data;
unsigned short int checksum;
int size;
short int lsample, rsample;
int state, lastflip, laststate;
bufferpos = 0;
pollfd.fd = opts.tundev;
pollfd.events = POLLIN;
state = -1;
laststate = -1;
lastflip = 0;
while( ! *(opts.done) )
{
if( poll( &pollfd, 1, 0 ) )
{
size = read( opts.tundev, databuffer, DATABUFFERSIZE-2 );
if( size == -1 )
{
perror( "output_loop: read" );
return NULL;
}
checksum = fletcher16( databuffer, size );
databuffer[size++] = (checksum>>8)&0xff;
databuffer[size++] = checksum&0xff;
fprintf( stderr, "< %i bytes, checksum: 0x%04hX\n", size, checksum );
for( i=0; i<size; i++ )
{
data = databuffer[i];
for( j=0; j<8; j++ )
{
if( data & 0x01 )
{
if( laststate&0x01 )
{
if( laststate&0x02 )
state = 0x01;
else
state = 0x03;
}
else
{
if( lastflip )
state = 0x01;
else
state = 0x03;
lastflip = laststate&0x02;
}
}
else
{
if( laststate&0x01 )
{
if( lastflip )
state = 0x00;
else
state = 0x02;
lastflip = laststate&0x02;
}
else
{
if( laststate&0x02 )
state = 0x00;
else
state = 0x02;
}
}
laststate = state;
data >>= 1;
if( state == 0 )
{
lsample = SHRT_MIN;
rsample = SHRT_MIN;
}
else if( state == 1 )
{
lsample = SHRT_MIN;
rsample = SHRT_MAX;
}
else if( state == 2 )
{
lsample = SHRT_MAX;
rsample = SHRT_MAX;
}
else if( state == 3 )
{
lsample = SHRT_MAX;
rsample = SHRT_MIN;
}
for( k=0; k<opts.bitlength; k++ )
{
if( ! audio_out( opts.dspdev, lsample, rsample ) )
return NULL;
}
}
}
for( i=0; i<16*opts.bitlength; i++ )
{
if( ! audio_out( opts.dspdev, 0, 0 ) )
return NULL;
}
}
else
{
for( i=0; i<16*opts.bitlength; i++ )
{
if( ! audio_out( opts.dspdev, 0, 0 ) )
return NULL;
}
}
}
return NULL;
}