ref: e7049a7fde1f7646df3dcb5a24a877b54dad59b7
dir: /src/src_zoh.c/
/*
** Copyright (C) 2002-2009 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.
*/
/*
** This code is part of Secret Rabibt Code aka libsamplerate. A commercial
** use license for this code is available, please see:
** http://www.mega-nerd.com/SRC/procedure.html
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "config.h"
#include "float_cast.h"
#include "common.h"
static int zoh_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ;
static void zoh_reset (SRC_PRIVATE *psrc) ;
/*========================================================================================
*/
#define ZOH_MAGIC_MARKER MAKE_MAGIC ('s', 'r', 'c', 'z', 'o', 'h')
typedef struct
{ int zoh_magic_marker ;
int channels ;
int reset ;
long in_count, in_used ;
long out_count, out_gen ;
float last_value [1] ;
} ZOH_DATA ;
/*----------------------------------------------------------------------------------------
*/
static int
zoh_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data)
{ ZOH_DATA *priv ;
double src_ratio, input_index, rem ;
int ch ;
if (data->input_frames <= 0)
return SRC_ERR_NO_ERROR ;
if (psrc->private_data == NULL)
return SRC_ERR_NO_PRIVATE ;
priv = (ZOH_DATA*) psrc->private_data ;
if (priv->reset)
{ /* If we have just been reset, set the last_value data. */
for (ch = 0 ; ch < priv->channels ; ch++)
priv->last_value [ch] = data->data_in [ch] ;
priv->reset = 0 ;
} ;
priv->in_count = data->input_frames * priv->channels ;
priv->out_count = data->output_frames * priv->channels ;
priv->in_used = priv->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 && priv->out_gen < priv->out_count)
{
if (priv->in_used + priv->channels * input_index >= priv->in_count)
break ;
if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ;
for (ch = 0 ; ch < priv->channels ; ch++)
{ data->data_out [priv->out_gen] = priv->last_value [ch] ;
priv->out_gen ++ ;
} ;
/* Figure out the next index. */
input_index += 1.0 / src_ratio ;
} ;
rem = fmod_one (input_index) ;
priv->in_used += priv->channels * lrint (input_index - rem) ;
input_index = rem ;
/* Main processing loop. */
while (priv->out_gen < priv->out_count && priv->in_used + priv->channels * input_index <= priv->in_count)
{
if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ;
for (ch = 0 ; ch < priv->channels ; ch++)
{ data->data_out [priv->out_gen] = data->data_in [priv->in_used - priv->channels + ch] ;
priv->out_gen ++ ;
} ;
/* Figure out the next index. */
input_index += 1.0 / src_ratio ;
rem = fmod_one (input_index) ;
priv->in_used += priv->channels * lrint (input_index - rem) ;
input_index = rem ;
} ;
if (priv->in_used > priv->in_count)
{ input_index += (priv->in_used - priv->in_count) / priv->channels ;
priv->in_used = priv->in_count ;
} ;
psrc->last_position = input_index ;
if (priv->in_used > 0)
for (ch = 0 ; ch < priv->channels ; ch++)
priv->last_value [ch] = data->data_in [priv->in_used - priv->channels + ch] ;
/* Save current ratio rather then target ratio. */
psrc->last_ratio = src_ratio ;
data->input_frames_used = priv->in_used / priv->channels ;
data->output_frames_gen = priv->out_gen / priv->channels ;
return SRC_ERR_NO_ERROR ;
} /* zoh_vari_process */
/*------------------------------------------------------------------------------
*/
const char*
zoh_get_name (int src_enum)
{
if (src_enum == SRC_ZERO_ORDER_HOLD)
return "ZOH Interpolator" ;
return NULL ;
} /* zoh_get_name */
const char*
zoh_get_description (int src_enum)
{
if (src_enum == SRC_ZERO_ORDER_HOLD)
return "Zero order hold interpolator, very fast, poor quality." ;
return NULL ;
} /* zoh_get_descrition */
int
zoh_set_converter (SRC_PRIVATE *psrc, int src_enum)
{ ZOH_DATA *priv = NULL ;
if (src_enum != SRC_ZERO_ORDER_HOLD)
return SRC_ERR_BAD_CONVERTER ;
if (psrc->private_data != NULL)
{ free (psrc->private_data) ;
psrc->private_data = NULL ;
} ;
if (psrc->private_data == NULL)
{ priv = calloc (1, sizeof (*priv) + psrc->channels * sizeof (float)) ;
if (priv == NULL)
return SRC_ERR_MALLOC_FAILED ;
psrc->private_data = priv ;
} ;
priv->zoh_magic_marker = ZOH_MAGIC_MARKER ;
priv->channels = psrc->channels ;
psrc->const_process = zoh_vari_process ;
psrc->vari_process = zoh_vari_process ;
psrc->reset = zoh_reset ;
zoh_reset (psrc) ;
return SRC_ERR_NO_ERROR ;
} /* zoh_set_converter */
/*===================================================================================
*/
static void
zoh_reset (SRC_PRIVATE *psrc)
{ ZOH_DATA *priv ;
priv = (ZOH_DATA*) psrc->private_data ;
if (priv == NULL)
return ;
priv->channels = psrc->channels ;
priv->reset = 1 ;
memset (priv->last_value, 0, sizeof (priv->last_value [0]) * priv->channels) ;
return ;
} /* zoh_reset */