1 files changed, 303 insertions, 0 deletions
diff --git a/src_linear.c b/src_linear.c
new file mode 100644
index 000000000000..175be4f5dd1d
--- /dev/null
+++ b/src_linear.c
@@ -0,0 +1,303 @@
+/*
+** Copyright (c) 2002-2021, 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
+*/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+#include "common.h"
+
+static SRC_ERROR linear_vari_process (SRC_STATE *state, SRC_DATA *data) ;
+static void linear_reset (SRC_STATE *state) ;
+static SRC_STATE *linear_copy (SRC_STATE *state) ;
+static void linear_close (SRC_STATE *state) ;
+
+/*========================================================================================
+*/
+
+#define	LINEAR_MAGIC_MARKER	MAKE_MAGIC ('l', 'i', 'n', 'e', 'a', 'r')
+
+#define	SRC_DEBUG	0
+
+typedef struct
+{	int		linear_magic_marker ;
+	bool	dirty ;
+	long	in_count, in_used ;
+	long	out_count, out_gen ;
+	float	*last_value ;
+} LINEAR_DATA ;
+
+static SRC_STATE_VT linear_state_vt =
+{
+	linear_vari_process,
+	linear_vari_process,
+	linear_reset,
+	linear_copy,
+	linear_close
+} ;
+
+/*----------------------------------------------------------------------------------------
+*/
+
+static SRC_ERROR
+linear_vari_process (SRC_STATE *state, SRC_DATA *data)
+{	LINEAR_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 = (LINEAR_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 * (1.0 + 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] = (float) (priv->last_value [ch] + input_index *
+										((double) data->data_in [ch] - 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 ;
+
+#if SRC_DEBUG
+		if (priv->in_used < state->channels && input_index < 1.0)
+		{	printf ("Whoops!!!!   in_used : %ld     channels : %d     input_index : %f\n", priv->in_used, state->channels, input_index) ;
+			exit (1) ;
+			} ;
+#endif
+
+		for (ch = 0 ; ch < state->channels ; ch++)
+		{	data->data_out [priv->out_gen] = (float) (data->data_in [priv->in_used - state->channels + ch] + input_index *
+						((double) data->data_in [priv->in_used + ch] - 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 ;
+} /* linear_vari_process */
+
+/*------------------------------------------------------------------------------
+*/
+
+#if 0
+LIBSAMPLERATE_DLL_PRIVATE const char*
+linear_get_name (int src_enum)
+{
+	if (src_enum == SRC_LINEAR)
+		return "Linear Interpolator" ;
+
+	return NULL ;
+} /* linear_get_name */
+
+LIBSAMPLERATE_DLL_PRIVATE 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 */
+#endif
+
+static LINEAR_DATA *
+linear_data_new (int channels)
+{
+	assert (channels > 0) ;
+
+	LINEAR_DATA *priv = (LINEAR_DATA *) calloc (1, sizeof (LINEAR_DATA)) ;
+	if (priv)
+	{
+		priv->linear_magic_marker = LINEAR_MAGIC_MARKER ;
+		priv->last_value = (float *) calloc (channels, sizeof (float)) ;
+		if (!priv->last_value)
+		{
+			free (priv) ;
+			priv = NULL ;
+		}
+	}
+
+	return priv ;
+}
+
+LIBSAMPLERATE_DLL_PRIVATE SRC_STATE *
+linear_state_new (int channels, SRC_ERROR *error)
+{
+	assert (channels > 0) ;
+	assert (error != NULL) ;
+
+	SRC_STATE *state = (SRC_STATE *) calloc (1, sizeof (SRC_STATE)) ;
+	if (!state)
+	{
+		*error = SRC_ERR_MALLOC_FAILED ;
+		return NULL ;
+	}
+
+	state->channels = channels ;
+	state->mode = SRC_MODE_PROCESS ;
+
+	state->private_data = linear_data_new (state->channels) ;
+	if (!state->private_data)
+	{
+		free (state) ;
+		*error = SRC_ERR_MALLOC_FAILED ;
+		return NULL ;
+	}
+
+	state->vt = &linear_state_vt ;
+
+	linear_reset (state) ;
+
+	*error = SRC_ERR_NO_ERROR ;
+
+	return state ;
+}
+
+/*===================================================================================
+*/
+
+static void
+linear_reset (SRC_STATE *state)
+{	LINEAR_DATA *priv = NULL ;
+
+	priv = (LINEAR_DATA*) state->private_data ;
+	if (priv == NULL)
+		return ;
+
+	priv->dirty = false ;
+	memset (priv->last_value, 0, sizeof (priv->last_value [0]) * state->channels) ;
+
+	return ;
+} /* linear_reset */
+
+SRC_STATE *
+linear_copy (SRC_STATE *state)
+{
+	assert (state != NULL) ;
+
+	if (state->private_data == NULL)
+		return NULL ;
+
+	SRC_STATE *to = (SRC_STATE *) calloc (1, sizeof (SRC_STATE)) ;
+	if (!to)
+		return NULL ;
+	memcpy (to, state, sizeof (SRC_STATE)) ;
+
+	LINEAR_DATA* from_priv = (LINEAR_DATA*) state->private_data ;
+	LINEAR_DATA *to_priv = (LINEAR_DATA *) calloc (1, sizeof (LINEAR_DATA)) ;
+	if (!to_priv)
+	{
+		free (to) ;
+		return NULL ;
+	}
+
+	memcpy (to_priv, from_priv, sizeof (LINEAR_DATA)) ;
+	to_priv->last_value = (float *) malloc (sizeof (float) * state->channels) ;
+	if (!to_priv->last_value)
+	{
+		free (to) ;
+		free (to_priv) ;
+		return NULL ;
+	}
+	memcpy (to_priv->last_value, from_priv->last_value, sizeof (float) * state->channels) ;
+
+	to->private_data = to_priv ;
+
+	return to ;
+} /* linear_copy */
+
+static void
+linear_close (SRC_STATE *state)
+{
+	if (state)
+	{
+		LINEAR_DATA *linear = (LINEAR_DATA *) state->private_data ;
+		if (linear)
+		{
+			if (linear->last_value)
+			{
+				free (linear->last_value) ;
+				linear->last_value = NULL ;
+			}
+			free (linear) ;
+			linear = NULL ;
+		}
+		free (state) ;
+		state = NULL ;
+	}
+} /* linear_close */