--- /dev/null
+/*
+** 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/erikd/libsamplerate/blob/master/COPYING
+*/
+
+#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 ;
+
+ if (is_bad_src_ratio (src_ratio))
+ return SRC_ERR_BAD_INTERNAL_STATE ;
+
+ 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)) ;
+ psrc->private_data = priv ;
+ } ;
+
+ if (priv == NULL)
+ return SRC_ERR_MALLOC_FAILED ;
+
+ 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 */
+
projects / audio-libsamplerate.git / blobdiff