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Sourcecode: libsamplerate version File versions

src_linear.c

/*
** Copyright (C) 2002-2004 Erik de Castro Lopo <erikd@mega-nerd.com>
**
** 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "config.h"
#include "float_cast.h"
#include "common.h"

static int linear_process (SRC_PRIVATE *psrc, SRC_DATA *data) ;
static void linear_reset (SRC_PRIVATE *psrc) ;

/*========================================================================================
*/

#define     LINEAR_MAGIC_MARKER     MAKE_MAGIC ('l', 'i', 'n', 'e', 'a', 'r')

#define     SRC_DEBUG   0

typedef struct
{     int         linear_magic_marker ;
      int         channels ;
      long  in_count, in_used ;
      long  out_count, out_gen ;
      float last_value [1] ;
} LINEAR_DATA ;

/*----------------------------------------------------------------------------------------
*/

static int
linear_process (SRC_PRIVATE *psrc, SRC_DATA *data)
{     LINEAR_DATA *linear ;
      double            src_ratio, input_index ;
      int               ch ;

      if (psrc->private_data == NULL)
            return SRC_ERR_NO_PRIVATE ;

      linear = (LINEAR_DATA*) psrc->private_data ;

      linear->in_count = data->input_frames * linear->channels ;
      linear->out_count = data->output_frames * linear->channels ;
      linear->in_used = linear->out_gen = 0 ;

      src_ratio = psrc->last_ratio ;
      input_index = psrc->last_position ;

      /* Calculate samples before first sample in input array. */
      while (input_index < 1.0 && linear->out_gen < linear->out_count)
      {
            if (linear->in_used + linear->channels * input_index > linear->in_count)
                  break ;

            if (fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
                  src_ratio = psrc->last_ratio + linear->out_gen * (data->src_ratio - psrc->last_ratio) / (linear->out_count - 1) ;

            for (ch = 0 ; ch < linear->channels ; ch++)
            {     data->data_out [linear->out_gen] = linear->last_value [ch] + input_index *
                                                            (data->data_in [ch] - linear->last_value [ch]) ;
                  linear->out_gen ++ ;
                  } ;

            /* Figure out the next index. */
            input_index += 1.0 / src_ratio ;
            } ;

      linear->in_used += linear->channels * lrint (floor (input_index)) ;
      input_index -= floor (input_index) ;

      /* Main processing loop. */
      while (linear->out_gen < linear->out_count && linear->in_used + linear->channels * input_index <= linear->in_count)
      {
            if (fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
                  src_ratio = psrc->last_ratio + linear->out_gen * (data->src_ratio - psrc->last_ratio) / (linear->out_count - 1) ;

            if (SRC_DEBUG && linear->in_used < linear->channels && input_index < 1.0)
            {     printf ("Whoops!!!!   in_used : %ld     channels : %d     input_index : %f\n", linear->in_used, linear->channels, input_index) ;
                  exit (1) ;
                  } ;

            for (ch = 0 ; ch < linear->channels ; ch++)
            {     data->data_out [linear->out_gen] = data->data_in [linear->in_used - linear->channels + ch] + input_index *
                                    (data->data_in [linear->in_used + ch] - data->data_in [linear->in_used - linear->channels + ch]) ;
                  linear->out_gen ++ ;
                  } ;

            /* Figure out the next index. */
            input_index += 1.0 / src_ratio ;

            linear->in_used += linear->channels * lrint (floor (input_index)) ;
            input_index -= floor (input_index) ;
            } ;

      if (linear->in_used > linear->in_count)
      {     input_index += linear->in_used - linear->in_count ;
            linear->in_used = linear->in_count ;
            } ;

      psrc->last_position = input_index ;

      if (linear->in_used > 0)
            for (ch = 0 ; ch < linear->channels ; ch++)
                  linear->last_value [ch] = data->data_in [linear->in_used - linear->channels + ch] ;

      /* Save current ratio rather then target ratio. */
      psrc->last_ratio = src_ratio ;

      data->input_frames_used = linear->in_used / linear->channels ;
      data->output_frames_gen = linear->out_gen / linear->channels ;

      return SRC_ERR_NO_ERROR ;
} /* linear_process */

/*------------------------------------------------------------------------------
*/

const char*
linear_get_name (int src_enum)
{
      if (src_enum == SRC_LINEAR)
            return "Linear Interpolator" ;

      return NULL ;
} /* linear_get_name */

const char*
linear_get_description (int src_enum)
{
      if (src_enum == SRC_LINEAR)
            return "Linear interpolator, very fast, poor quality." ;

      return NULL ;
} /* linear_get_descrition */

int
linear_set_converter (SRC_PRIVATE *psrc, int src_enum)
{     LINEAR_DATA *linear = NULL ;

      if (src_enum != SRC_LINEAR)
            return SRC_ERR_BAD_CONVERTER ;

      if (psrc->private_data != NULL)
      {     linear = (LINEAR_DATA*) psrc->private_data ;
            if (linear->linear_magic_marker != LINEAR_MAGIC_MARKER)
            {     free (psrc->private_data) ;
                  psrc->private_data = NULL ;
                  } ;
            } ;

      if (psrc->private_data == NULL)
      {     linear = calloc (1, sizeof (*linear) + psrc->channels * sizeof (float)) ;
            if (linear == NULL)
                  return SRC_ERR_MALLOC_FAILED ;
            psrc->private_data = linear ;
            } ;

      linear->linear_magic_marker = LINEAR_MAGIC_MARKER ;
      linear->channels = psrc->channels ;

      psrc->process = linear_process ;
      psrc->reset = linear_reset ;

      linear_reset (psrc) ;

      return SRC_ERR_NO_ERROR ;
} /* linear_set_converter */

/*===================================================================================
*/

static void
linear_reset (SRC_PRIVATE *psrc)
{     LINEAR_DATA *linear = NULL ;

      linear = (LINEAR_DATA*) psrc->private_data ;
      if (linear == NULL)
            return ;

      memset (linear->last_value, 0, sizeof (linear->last_value [0]) * linear->channels) ;
} /* linear_reset */
/*
** Do not edit or modify anything in this comment block.
** The arch-tag line is a file identity tag for the GNU Arch 
** revision control system.
**
** arch-tag: 7eac3103-3d84-45d3-8bbd-f409c2b2d1a9
*/


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