ref: 5f60997fe351d62b1eab9face1fbd9d51655aff3
dir: /src/src_zoh.c/
/*
** Copyright (c) 2002-2016, Erik de Castro Lopo <erikd@mega-nerd.com>
** All rights reserved.
**
** This code is released under 2-clause BSD license. Please see the
** file at : https://github.com/libsndfile/libsamplerate/blob/master/COPYING
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "src_config.h"
#include "common.h"
static SRC_ERROR zoh_vari_process (SRC_STATE *state, SRC_DATA *data) ;
static void zoh_reset (SRC_STATE *state) ;
static SRC_ERROR zoh_copy (SRC_STATE *from, SRC_STATE *to) ;
static void zoh_close (SRC_STATE *state) ;
/*========================================================================================
*/
#define ZOH_MAGIC_MARKER MAKE_MAGIC ('s', 'r', 'c', 'z', 'o', 'h')
typedef struct
{ int zoh_magic_marker ;
bool dirty ;
long in_count, in_used ;
long out_count, out_gen ;
float *last_value ;
} ZOH_DATA ;
/*----------------------------------------------------------------------------------------
*/
static SRC_ERROR
zoh_vari_process (SRC_STATE *state, 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 (state->private_data == NULL)
return SRC_ERR_NO_PRIVATE ;
priv = (ZOH_DATA*) state->private_data ;
if (!priv->dirty)
{ /* If we have just been reset, set the last_value data. */
for (ch = 0 ; ch < state->channels ; ch++)
priv->last_value [ch] = data->data_in [ch] ;
priv->dirty = true ;
} ;
priv->in_count = data->input_frames * state->channels ;
priv->out_count = data->output_frames * state->channels ;
priv->in_used = priv->out_gen = 0 ;
src_ratio = state->last_ratio ;
if (is_bad_src_ratio (src_ratio))
return SRC_ERR_BAD_INTERNAL_STATE ;
input_index = state->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 + state->channels * input_index >= priv->in_count)
break ;
if (priv->out_count > 0 && fabs (state->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
src_ratio = state->last_ratio + priv->out_gen * (data->src_ratio - state->last_ratio) / priv->out_count ;
for (ch = 0 ; ch < state->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 += state->channels * lrint (input_index - rem) ;
input_index = rem ;
/* Main processing loop. */
while (priv->out_gen < priv->out_count && priv->in_used + state->channels * input_index <= priv->in_count)
{
if (priv->out_count > 0 && fabs (state->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
src_ratio = state->last_ratio + priv->out_gen * (data->src_ratio - state->last_ratio) / priv->out_count ;
for (ch = 0 ; ch < state->channels ; ch++)
{ data->data_out [priv->out_gen] = data->data_in [priv->in_used - state->channels + ch] ;
priv->out_gen ++ ;
} ;
/* Figure out the next index. */
input_index += 1.0 / src_ratio ;
rem = fmod_one (input_index) ;
priv->in_used += state->channels * lrint (input_index - rem) ;
input_index = rem ;
} ;
if (priv->in_used > priv->in_count)
{ input_index += (priv->in_used - priv->in_count) / state->channels ;
priv->in_used = priv->in_count ;
} ;
state->last_position = input_index ;
if (priv->in_used > 0)
for (ch = 0 ; ch < state->channels ; ch++)
priv->last_value [ch] = data->data_in [priv->in_used - state->channels + ch] ;
/* Save current ratio rather then target ratio. */
state->last_ratio = src_ratio ;
data->input_frames_used = priv->in_used / state->channels ;
data->output_frames_gen = priv->out_gen / state->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 */
SRC_ERROR
zoh_set_converter (SRC_STATE *state, int src_enum)
{
ZOH_DATA *priv = NULL ;
if (src_enum != SRC_ZERO_ORDER_HOLD)
return SRC_ERR_BAD_CONVERTER ;
zoh_close (state) ;
if (state->private_data == NULL)
{
priv = (ZOH_DATA *) calloc (1, sizeof (ZOH_DATA)) ;
if (priv)
{
priv->last_value = calloc (state->channels, sizeof (float)) ;
if (!priv->last_value)
{
free (priv) ;
priv = NULL ;
}
}
}
if (priv == NULL)
return SRC_ERR_MALLOC_FAILED ;
state->private_data = priv ;
priv->zoh_magic_marker = ZOH_MAGIC_MARKER ;
state->const_process = zoh_vari_process ;
state->vari_process = zoh_vari_process ;
state->reset = zoh_reset ;
state->copy = zoh_copy ;
state->close = zoh_close ;
zoh_reset (state) ;
return SRC_ERR_NO_ERROR ;
} /* zoh_set_converter */
/*===================================================================================
*/
static void
zoh_reset (SRC_STATE *state)
{ ZOH_DATA *priv ;
priv = (ZOH_DATA*) state->private_data ;
if (priv == NULL)
return ;
priv->dirty = false ;
memset (priv->last_value, 0, sizeof (float) * state->channels) ;
return ;
} /* zoh_reset */
static SRC_ERROR
zoh_copy (SRC_STATE *from, SRC_STATE *to)
{
if (from->private_data == NULL)
return SRC_ERR_NO_PRIVATE ;
ZOH_DATA *to_priv = NULL ;
ZOH_DATA* from_priv = (ZOH_DATA*) from->private_data ;
if ((to_priv = (ZOH_DATA *) calloc (1, sizeof (ZOH_DATA))) == NULL)
return SRC_ERR_MALLOC_FAILED ;
memcpy (to_priv, from_priv, sizeof (ZOH_DATA)) ;
to_priv->last_value = malloc (sizeof (float) * from->channels) ;
if (!to_priv->last_value)
{ free (to_priv) ;
return SRC_ERR_MALLOC_FAILED ;
} ;
memcpy (to_priv->last_value, from_priv->last_value, sizeof (float) * from->channels) ;
to->private_data = to_priv ;
return SRC_ERR_NO_ERROR ;
} /* zoh_copy */
static void
zoh_close (SRC_STATE *state)
{
if (state)
{
ZOH_DATA *zoh = (ZOH_DATA *) state->private_data ;
if (zoh)
{
if (zoh->last_value)
{ free (zoh->last_value) ;
zoh->last_value = NULL ;
} ;
free (zoh) ;
zoh = NULL ;
}
}
} /* zoh_close */