112 lines
3.0 KiB
C
112 lines
3.0 KiB
C
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/*******************************************************************************/
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/* Copyright (C) 2008 Jonathan Moore Liles */
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/* */
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/* This program is free software; you can redistribute it and/or modify it */
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/* under the terms of the GNU General Public License as published by the */
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/* Free Software Foundation; either version 2 of the License, or (at your */
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/* option) any later version. */
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/* */
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/* This program is distributed in the hope that it will be useful, but WITHOUT */
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/* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or */
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/* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for */
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/* more details. */
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/* */
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/* You should have received a copy of the GNU General Public License along */
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/* with This program; see the file COPYING. If not,write to the Free Software */
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/* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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/*******************************************************************************/
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#include "Peaks.H"
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#include "Timeline.H"
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#include <sys/mman.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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void
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Peaks::downsample ( int s, int e, float *mhi, float *mlo ) const
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{
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*mhi = -1.0;
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*mlo = 1.0;
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if ( e > _len )
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e = _len;
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for ( int j = s; j < e; j++ )
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{
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const float lo = _peaks->data[ j ].min;
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const float hi = _peaks->data[ j ].max;
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if ( hi > *mhi )
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*mhi = hi;
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if ( lo < *mlo )
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*mlo = lo;
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}
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}
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void
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Peaks::read ( int X, float *hi, float *lo ) const
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{
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int start = X * timeline.fpp;
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int end = (X + 1) * timeline.fpp;
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downsample( start, end, hi, lo );
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}
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/* virtual array. Index is a Pixel value, and it returns the
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* (resampled) peaks for that pixel based on the current timeline
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* zoom. */
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Peak &
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Peaks::operator[] ( int X ) const
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{
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/* Is there a better way to return this? */
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static Peak p;
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int start = X * timeline.fpp;
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int end = (X + 1) * timeline.fpp;
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downsample( start, end, &p.max, &p.min );
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return p;
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}
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bool
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Peaks::open ( const char *filename )
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{
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char file[512];
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snprintf( file, 512, "%s.peak", filename );
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int fd;
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if ( ( fd = ::open( file, O_RDONLY ) ) < 0 )
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{
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/* generate peaks here */
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}
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{
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struct stat st;
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fstat( fd, &st );
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_len = st.st_size;
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}
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_peaks = (peaks*)mmap( NULL, _len, PROT_READ, MAP_SHARED, fd, 0 );
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::close( fd );
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if ( _peaks == MAP_FAILED )
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printf( "failed to create mapping! " );
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_len = (_len - sizeof( int )) / sizeof( Peak );
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return true;
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}
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