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src_sinc.c
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src_sinc.c
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/*
** 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 <math.h>
#include "src_config.h"
#include "common.h"
#define SINC_MAGIC_MARKER MAKE_MAGIC (' ', 's', 'i', 'n', 'c', ' ')
/*========================================================================================
*/
#define MAKE_INCREMENT_T(x) ((increment_t) (x))
#define SHIFT_BITS 12
#define FP_ONE ((double) (((increment_t) 1) << SHIFT_BITS))
#define INV_FP_ONE (1.0 / FP_ONE)
/*========================================================================================
*/
typedef int32_t increment_t ;
typedef float coeff_t ;
#include "fastest_coeffs.h"
#include "mid_qual_coeffs.h"
#include "high_qual_coeffs.h"
typedef struct
{ int sinc_magic_marker ;
int channels ;
long in_count, in_used ;
long out_count, out_gen ;
int coeff_half_len, index_inc ;
double src_ratio, input_index ;
coeff_t const *coeffs ;
int b_current, b_end, b_real_end, b_len ;
/* Sure hope noone does more than 128 channels at once. */
double left_calc [128], right_calc [128] ;
/* C99 struct flexible array. */
float buffer [] ;
} SINC_FILTER ;
static int sinc_multichan_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ;
static int sinc_hex_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ;
static int sinc_quad_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ;
static int sinc_stereo_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ;
static int sinc_mono_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ;
static int prepare_data (SINC_FILTER *filter, SRC_DATA *data, int half_filter_chan_len) WARN_UNUSED ;
static void sinc_reset (SRC_PRIVATE *psrc) ;
static int sinc_copy (SRC_PRIVATE *from, SRC_PRIVATE *to) ;
static inline increment_t
double_to_fp (double x)
{ return (increment_t) (lrint ((x) * FP_ONE)) ;
} /* double_to_fp */
static inline increment_t
int_to_fp (int x)
{ return (((increment_t) (x)) << SHIFT_BITS) ;
} /* int_to_fp */
static inline int
fp_to_int (increment_t x)
{ return (((x) >> SHIFT_BITS)) ;
} /* fp_to_int */
static inline increment_t
fp_fraction_part (increment_t x)
{ return ((x) & ((((increment_t) 1) << SHIFT_BITS) - 1)) ;
} /* fp_fraction_part */
static inline double
fp_to_double (increment_t x)
{ return fp_fraction_part (x) * INV_FP_ONE ;
} /* fp_to_double */
/*----------------------------------------------------------------------------------------
*/
const char*
sinc_get_name (int src_enum)
{
switch (src_enum)
{ case SRC_SINC_BEST_QUALITY :
return "Best Sinc Interpolator" ;
case SRC_SINC_MEDIUM_QUALITY :
return "Medium Sinc Interpolator" ;
case SRC_SINC_FASTEST :
return "Fastest Sinc Interpolator" ;
default: break ;
} ;
return NULL ;
} /* sinc_get_descrition */
const char*
sinc_get_description (int src_enum)
{
switch (src_enum)
{ case SRC_SINC_FASTEST :
return "Band limited sinc interpolation, fastest, 97dB SNR, 80% BW." ;
case SRC_SINC_MEDIUM_QUALITY :
return "Band limited sinc interpolation, medium quality, 121dB SNR, 90% BW." ;
case SRC_SINC_BEST_QUALITY :
return "Band limited sinc interpolation, best quality, 144dB SNR, 96% BW." ;
default :
break ;
} ;
return NULL ;
} /* sinc_get_descrition */
int
sinc_set_converter (SRC_PRIVATE *psrc, int src_enum)
{ SINC_FILTER *filter, temp_filter ;
increment_t count ;
uint32_t bits ;
/* Quick sanity check. */
if (SHIFT_BITS >= sizeof (increment_t) * 8 - 1)
return SRC_ERR_SHIFT_BITS ;
if (psrc->private_data != NULL)
{ free (psrc->private_data) ;
psrc->private_data = NULL ;
} ;
memset (&temp_filter, 0, sizeof (temp_filter)) ;
temp_filter.sinc_magic_marker = SINC_MAGIC_MARKER ;
temp_filter.channels = psrc->channels ;
if (psrc->channels > ARRAY_LEN (temp_filter.left_calc))
return SRC_ERR_BAD_CHANNEL_COUNT ;
else if (psrc->channels == 1)
{ psrc->const_process = sinc_mono_vari_process ;
psrc->vari_process = sinc_mono_vari_process ;
}
else
if (psrc->channels == 2)
{ psrc->const_process = sinc_stereo_vari_process ;
psrc->vari_process = sinc_stereo_vari_process ;
}
else
if (psrc->channels == 4)
{ psrc->const_process = sinc_quad_vari_process ;
psrc->vari_process = sinc_quad_vari_process ;
}
else
if (psrc->channels == 6)
{ psrc->const_process = sinc_hex_vari_process ;
psrc->vari_process = sinc_hex_vari_process ;
}
else
{ psrc->const_process = sinc_multichan_vari_process ;
psrc->vari_process = sinc_multichan_vari_process ;
} ;
psrc->reset = sinc_reset ;
psrc->copy = sinc_copy ;
switch (src_enum)
{ case SRC_SINC_FASTEST :
temp_filter.coeffs = fastest_coeffs.coeffs ;
temp_filter.coeff_half_len = ARRAY_LEN (fastest_coeffs.coeffs) - 2 ;
temp_filter.index_inc = fastest_coeffs.increment ;
break ;
case SRC_SINC_MEDIUM_QUALITY :
temp_filter.coeffs = slow_mid_qual_coeffs.coeffs ;
temp_filter.coeff_half_len = ARRAY_LEN (slow_mid_qual_coeffs.coeffs) - 2 ;
temp_filter.index_inc = slow_mid_qual_coeffs.increment ;
break ;
case SRC_SINC_BEST_QUALITY :
temp_filter.coeffs = slow_high_qual_coeffs.coeffs ;
temp_filter.coeff_half_len = ARRAY_LEN (slow_high_qual_coeffs.coeffs) - 2 ;
temp_filter.index_inc = slow_high_qual_coeffs.increment ;
break ;
default :
return SRC_ERR_BAD_CONVERTER ;
} ;
/*
** FIXME : This needs to be looked at more closely to see if there is
** a better way. Need to look at prepare_data () at the same time.
*/
temp_filter.b_len = (int) lrint (2.5 * temp_filter.coeff_half_len / (temp_filter.index_inc * 1.0) * SRC_MAX_RATIO) ;
temp_filter.b_len = MAX (temp_filter.b_len, 4096) ;
temp_filter.b_len *= temp_filter.channels ;
if ((filter = ZERO_ALLOC (SINC_FILTER, sizeof (SINC_FILTER) + sizeof (filter->buffer [0]) * (temp_filter.b_len + temp_filter.channels))) == NULL)
return SRC_ERR_MALLOC_FAILED ;
*filter = temp_filter ;
memset (&temp_filter, 0xEE, sizeof (temp_filter)) ;
psrc->private_data = filter ;
sinc_reset (psrc) ;
count = filter->coeff_half_len ;
for (bits = 0 ; (MAKE_INCREMENT_T (1) << bits) < count ; bits++)
count |= (MAKE_INCREMENT_T (1) << bits) ;
if (bits + SHIFT_BITS - 1 >= (int) (sizeof (increment_t) * 8))
return SRC_ERR_FILTER_LEN ;
return SRC_ERR_NO_ERROR ;
} /* sinc_set_converter */
static void
sinc_reset (SRC_PRIVATE *psrc)
{ SINC_FILTER *filter ;
filter = (SINC_FILTER*) psrc->private_data ;
if (filter == NULL)
return ;
filter->b_current = filter->b_end = 0 ;
filter->b_real_end = -1 ;
filter->src_ratio = filter->input_index = 0.0 ;
memset (filter->buffer, 0, filter->b_len * sizeof (filter->buffer [0])) ;
/* Set this for a sanity check */
memset (filter->buffer + filter->b_len, 0xAA, filter->channels * sizeof (filter->buffer [0])) ;
} /* sinc_reset */
static int
sinc_copy (SRC_PRIVATE *from, SRC_PRIVATE *to)
{
if (from->private_data == NULL)
return SRC_ERR_NO_PRIVATE ;
SINC_FILTER *to_filter = NULL ;
SINC_FILTER* from_filter = (SINC_FILTER*) from->private_data ;
size_t private_length = sizeof (SINC_FILTER) + sizeof (from_filter->buffer [0]) * (from_filter->b_len + from_filter->channels) ;
if ((to_filter = ZERO_ALLOC (SINC_FILTER, private_length)) == NULL)
return SRC_ERR_MALLOC_FAILED ;
memcpy (to_filter, from_filter, private_length) ;
to->private_data = to_filter ;
return SRC_ERR_NO_ERROR ;
} /* sinc_copy */
/*========================================================================================
** Beware all ye who dare pass this point. There be dragons here.
*/
static inline double
calc_output_single (SINC_FILTER *filter, increment_t increment, increment_t start_filter_index)
{ double fraction, left, right, icoeff ;
increment_t filter_index, max_filter_index ;
int data_index, coeff_count, indx ;
/* Convert input parameters into fixed point. */
max_filter_index = int_to_fp (filter->coeff_half_len) ;
/* First apply the left half of the filter. */
filter_index = start_filter_index ;
coeff_count = (max_filter_index - filter_index) / increment ;
filter_index = filter_index + coeff_count * increment ;
data_index = filter->b_current - coeff_count ;
left = 0.0 ;
do
{ if (data_index >= 0) /* Avoid underflow access to filter->buffer. */
{ fraction = fp_to_double (filter_index) ;
indx = fp_to_int (filter_index) ;
icoeff = filter->coeffs [indx] + fraction * (filter->coeffs [indx + 1] - filter->coeffs [indx]) ;
left += icoeff * filter->buffer [data_index] ;
} ;
filter_index -= increment ;
data_index = data_index + 1 ;
}
while (filter_index >= MAKE_INCREMENT_T (0)) ;
/* Now apply the right half of the filter. */
filter_index = increment - start_filter_index ;
coeff_count = (max_filter_index - filter_index) / increment ;
filter_index = filter_index + coeff_count * increment ;
data_index = filter->b_current + 1 + coeff_count ;
right = 0.0 ;
do
{ fraction = fp_to_double (filter_index) ;
indx = fp_to_int (filter_index) ;
icoeff = filter->coeffs [indx] + fraction * (filter->coeffs [indx + 1] - filter->coeffs [indx]) ;
right += icoeff * filter->buffer [data_index] ;
filter_index -= increment ;
data_index = data_index - 1 ;
}
while (filter_index > MAKE_INCREMENT_T (0)) ;
return (left + right) ;
} /* calc_output_single */
static int
sinc_mono_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data)
{ SINC_FILTER *filter ;
double input_index, src_ratio, count, float_increment, terminate, rem ;
increment_t increment, start_filter_index ;
int half_filter_chan_len, samples_in_hand ;
if (psrc->private_data == NULL)
return SRC_ERR_NO_PRIVATE ;
filter = (SINC_FILTER*) psrc->private_data ;
/* If there is not a problem, this will be optimised out. */
if (sizeof (filter->buffer [0]) != sizeof (data->data_in [0]))
return SRC_ERR_SIZE_INCOMPATIBILITY ;
filter->in_count = data->input_frames * filter->channels ;
filter->out_count = data->output_frames * filter->channels ;
filter->in_used = filter->out_gen = 0 ;
src_ratio = psrc->last_ratio ;
if (is_bad_src_ratio (src_ratio))
return SRC_ERR_BAD_INTERNAL_STATE ;
/* Check the sample rate ratio wrt the buffer len. */
count = (filter->coeff_half_len + 2.0) / filter->index_inc ;
if (MIN (psrc->last_ratio, data->src_ratio) < 1.0)
count /= MIN (psrc->last_ratio, data->src_ratio) ;
/* Maximum coefficientson either side of center point. */
half_filter_chan_len = filter->channels * (int) (lrint (count) + 1) ;
input_index = psrc->last_position ;
rem = fmod_one (input_index) ;
filter->b_current = (filter->b_current + filter->channels * lrint (input_index - rem)) % filter->b_len ;
input_index = rem ;
terminate = 1.0 / src_ratio + 1e-20 ;
/* Main processing loop. */
while (filter->out_gen < filter->out_count)
{
/* Need to reload buffer? */
samples_in_hand = (filter->b_end - filter->b_current + filter->b_len) % filter->b_len ;
if (samples_in_hand <= half_filter_chan_len)
{ if ((psrc->error = prepare_data (filter, data, half_filter_chan_len)) != 0)
return psrc->error ;
samples_in_hand = (filter->b_end - filter->b_current + filter->b_len) % filter->b_len ;
if (samples_in_hand <= half_filter_chan_len)
break ;
} ;
/* This is the termination condition. */
if (filter->b_real_end >= 0)
{ if (filter->b_current + input_index + terminate > filter->b_real_end)
break ;
} ;
if (filter->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > 1e-10)
src_ratio = psrc->last_ratio + filter->out_gen * (data->src_ratio - psrc->last_ratio) / filter->out_count ;
float_increment = filter->index_inc * (src_ratio < 1.0 ? src_ratio : 1.0) ;
increment = double_to_fp (float_increment) ;
start_filter_index = double_to_fp (input_index * float_increment) ;
data->data_out [filter->out_gen] = (float) ((float_increment / filter->index_inc) *
calc_output_single (filter, increment, start_filter_index)) ;
filter->out_gen ++ ;
/* Figure out the next index. */
input_index += 1.0 / src_ratio ;
rem = fmod_one (input_index) ;
filter->b_current = (filter->b_current + filter->channels * lrint (input_index - rem)) % filter->b_len ;
input_index = rem ;
} ;
psrc->last_position = input_index ;
/* Save current ratio rather then target ratio. */
psrc->last_ratio = src_ratio ;
data->input_frames_used = filter->in_used / filter->channels ;
data->output_frames_gen = filter->out_gen / filter->channels ;
return SRC_ERR_NO_ERROR ;
} /* sinc_mono_vari_process */
static inline void
calc_output_stereo (SINC_FILTER *filter, increment_t increment, increment_t start_filter_index, double scale, float * output)
{ double fraction, left [2], right [2], icoeff ;
increment_t filter_index, max_filter_index ;
int data_index, coeff_count, indx ;
/* Convert input parameters into fixed point. */
max_filter_index = int_to_fp (filter->coeff_half_len) ;
/* First apply the left half of the filter. */
filter_index = start_filter_index ;
coeff_count = (max_filter_index - filter_index) / increment ;
filter_index = filter_index + coeff_count * increment ;
data_index = filter->b_current - filter->channels * coeff_count ;
left [0] = left [1] = 0.0 ;
do
{ if (data_index >= 0) /* Avoid underflow access to filter->buffer. */
{ fraction = fp_to_double (filter_index) ;
indx = fp_to_int (filter_index) ;
icoeff = filter->coeffs [indx] + fraction * (filter->coeffs [indx + 1] - filter->coeffs [indx]) ;
left [0] += icoeff * filter->buffer [data_index] ;
left [1] += icoeff * filter->buffer [data_index + 1] ;
} ;
filter_index -= increment ;
data_index = data_index + 2 ;
}
while (filter_index >= MAKE_INCREMENT_T (0)) ;
/* Now apply the right half of the filter. */
filter_index = increment - start_filter_index ;
coeff_count = (max_filter_index - filter_index) / increment ;
filter_index = filter_index + coeff_count * increment ;
data_index = filter->b_current + filter->channels * (1 + coeff_count) ;
right [0] = right [1] = 0.0 ;
do
{ fraction = fp_to_double (filter_index) ;
indx = fp_to_int (filter_index) ;
icoeff = filter->coeffs [indx] + fraction * (filter->coeffs [indx + 1] - filter->coeffs [indx]) ;
right [0] += icoeff * filter->buffer [data_index] ;
right [1] += icoeff * filter->buffer [data_index + 1] ;
filter_index -= increment ;
data_index = data_index - 2 ;
}
while (filter_index > MAKE_INCREMENT_T (0)) ;
output [0] = scale * (left [0] + right [0]) ;
output [1] = scale * (left [1] + right [1]) ;
} /* calc_output_stereo */
static int
sinc_stereo_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data)
{ SINC_FILTER *filter ;
double input_index, src_ratio, count, float_increment, terminate, rem ;
increment_t increment, start_filter_index ;
int half_filter_chan_len, samples_in_hand ;
if (psrc->private_data == NULL)
return SRC_ERR_NO_PRIVATE ;
filter = (SINC_FILTER*) psrc->private_data ;
/* If there is not a problem, this will be optimised out. */
if (sizeof (filter->buffer [0]) != sizeof (data->data_in [0]))
return SRC_ERR_SIZE_INCOMPATIBILITY ;
filter->in_count = data->input_frames * filter->channels ;
filter->out_count = data->output_frames * filter->channels ;
filter->in_used = filter->out_gen = 0 ;
src_ratio = psrc->last_ratio ;
if (is_bad_src_ratio (src_ratio))
return SRC_ERR_BAD_INTERNAL_STATE ;
/* Check the sample rate ratio wrt the buffer len. */
count = (filter->coeff_half_len + 2.0) / filter->index_inc ;
if (MIN (psrc->last_ratio, data->src_ratio) < 1.0)
count /= MIN (psrc->last_ratio, data->src_ratio) ;
/* Maximum coefficientson either side of center point. */
half_filter_chan_len = filter->channels * (int) (lrint (count) + 1) ;
input_index = psrc->last_position ;
rem = fmod_one (input_index) ;
filter->b_current = (filter->b_current + filter->channels * lrint (input_index - rem)) % filter->b_len ;
input_index = rem ;
terminate = 1.0 / src_ratio + 1e-20 ;
/* Main processing loop. */
while (filter->out_gen < filter->out_count)
{
/* Need to reload buffer? */
samples_in_hand = (filter->b_end - filter->b_current + filter->b_len) % filter->b_len ;
if (samples_in_hand <= half_filter_chan_len)
{ if ((psrc->error = prepare_data (filter, data, half_filter_chan_len)) != 0)
return psrc->error ;
samples_in_hand = (filter->b_end - filter->b_current + filter->b_len) % filter->b_len ;
if (samples_in_hand <= half_filter_chan_len)
break ;
} ;
/* This is the termination condition. */
if (filter->b_real_end >= 0)
{ if (filter->b_current + input_index + terminate >= filter->b_real_end)
break ;
} ;
if (filter->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > 1e-10)
src_ratio = psrc->last_ratio + filter->out_gen * (data->src_ratio - psrc->last_ratio) / filter->out_count ;
float_increment = filter->index_inc * (src_ratio < 1.0 ? src_ratio : 1.0) ;
increment = double_to_fp (float_increment) ;
start_filter_index = double_to_fp (input_index * float_increment) ;
calc_output_stereo (filter, increment, start_filter_index, float_increment / filter->index_inc, data->data_out + filter->out_gen) ;
filter->out_gen += 2 ;
/* Figure out the next index. */
input_index += 1.0 / src_ratio ;
rem = fmod_one (input_index) ;
filter->b_current = (filter->b_current + filter->channels * lrint (input_index - rem)) % filter->b_len ;
input_index = rem ;
} ;
psrc->last_position = input_index ;
/* Save current ratio rather then target ratio. */
psrc->last_ratio = src_ratio ;
data->input_frames_used = filter->in_used / filter->channels ;
data->output_frames_gen = filter->out_gen / filter->channels ;
return SRC_ERR_NO_ERROR ;
} /* sinc_stereo_vari_process */
static inline void
calc_output_quad (SINC_FILTER *filter, increment_t increment, increment_t start_filter_index, double scale, float * output)
{ double fraction, left [4], right [4], icoeff ;
increment_t filter_index, max_filter_index ;
int data_index, coeff_count, indx ;
/* Convert input parameters into fixed point. */
max_filter_index = int_to_fp (filter->coeff_half_len) ;
/* First apply the left half of the filter. */
filter_index = start_filter_index ;
coeff_count = (max_filter_index - filter_index) / increment ;
filter_index = filter_index + coeff_count * increment ;
data_index = filter->b_current - filter->channels * coeff_count ;
left [0] = left [1] = left [2] = left [3] = 0.0 ;
do
{ if (data_index >= 0) /* Avoid underflow access to filter->buffer. */
{ fraction = fp_to_double (filter_index) ;
indx = fp_to_int (filter_index) ;
icoeff = filter->coeffs [indx] + fraction * (filter->coeffs [indx + 1] - filter->coeffs [indx]) ;
left [0] += icoeff * filter->buffer [data_index] ;
left [1] += icoeff * filter->buffer [data_index + 1] ;
left [2] += icoeff * filter->buffer [data_index + 2] ;
left [3] += icoeff * filter->buffer [data_index + 3] ;
} ;
filter_index -= increment ;
data_index = data_index + 4 ;
}
while (filter_index >= MAKE_INCREMENT_T (0)) ;
/* Now apply the right half of the filter. */
filter_index = increment - start_filter_index ;
coeff_count = (max_filter_index - filter_index) / increment ;
filter_index = filter_index + coeff_count * increment ;
data_index = filter->b_current + filter->channels * (1 + coeff_count) ;
right [0] = right [1] = right [2] = right [3] = 0.0 ;
do
{ fraction = fp_to_double (filter_index) ;
indx = fp_to_int (filter_index) ;
icoeff = filter->coeffs [indx] + fraction * (filter->coeffs [indx + 1] - filter->coeffs [indx]) ;
right [0] += icoeff * filter->buffer [data_index] ;
right [1] += icoeff * filter->buffer [data_index + 1] ;
right [2] += icoeff * filter->buffer [data_index + 2] ;
right [3] += icoeff * filter->buffer [data_index + 3] ;
filter_index -= increment ;
data_index = data_index - 4 ;
}
while (filter_index > MAKE_INCREMENT_T (0)) ;
output [0] = scale * (left [0] + right [0]) ;
output [1] = scale * (left [1] + right [1]) ;
output [2] = scale * (left [2] + right [2]) ;
output [3] = scale * (left [3] + right [3]) ;
} /* calc_output_quad */
static int
sinc_quad_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data)
{ SINC_FILTER *filter ;
double input_index, src_ratio, count, float_increment, terminate, rem ;
increment_t increment, start_filter_index ;
int half_filter_chan_len, samples_in_hand ;
if (psrc->private_data == NULL)
return SRC_ERR_NO_PRIVATE ;
filter = (SINC_FILTER*) psrc->private_data ;
/* If there is not a problem, this will be optimised out. */
if (sizeof (filter->buffer [0]) != sizeof (data->data_in [0]))
return SRC_ERR_SIZE_INCOMPATIBILITY ;
filter->in_count = data->input_frames * filter->channels ;
filter->out_count = data->output_frames * filter->channels ;
filter->in_used = filter->out_gen = 0 ;
src_ratio = psrc->last_ratio ;
if (is_bad_src_ratio (src_ratio))
return SRC_ERR_BAD_INTERNAL_STATE ;
/* Check the sample rate ratio wrt the buffer len. */
count = (filter->coeff_half_len + 2.0) / filter->index_inc ;
if (MIN (psrc->last_ratio, data->src_ratio) < 1.0)
count /= MIN (psrc->last_ratio, data->src_ratio) ;
/* Maximum coefficientson either side of center point. */
half_filter_chan_len = filter->channels * (int) (lrint (count) + 1) ;
input_index = psrc->last_position ;
rem = fmod_one (input_index) ;
filter->b_current = (filter->b_current + filter->channels * lrint (input_index - rem)) % filter->b_len ;
input_index = rem ;
terminate = 1.0 / src_ratio + 1e-20 ;
/* Main processing loop. */
while (filter->out_gen < filter->out_count)
{
/* Need to reload buffer? */
samples_in_hand = (filter->b_end - filter->b_current + filter->b_len) % filter->b_len ;
if (samples_in_hand <= half_filter_chan_len)
{ if ((psrc->error = prepare_data (filter, data, half_filter_chan_len)) != 0)
return psrc->error ;
samples_in_hand = (filter->b_end - filter->b_current + filter->b_len) % filter->b_len ;
if (samples_in_hand <= half_filter_chan_len)
break ;
} ;
/* This is the termination condition. */
if (filter->b_real_end >= 0)
{ if (filter->b_current + input_index + terminate >= filter->b_real_end)
break ;
} ;
if (filter->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > 1e-10)
src_ratio = psrc->last_ratio + filter->out_gen * (data->src_ratio - psrc->last_ratio) / filter->out_count ;
float_increment = filter->index_inc * (src_ratio < 1.0 ? src_ratio : 1.0) ;
increment = double_to_fp (float_increment) ;
start_filter_index = double_to_fp (input_index * float_increment) ;
calc_output_quad (filter, increment, start_filter_index, float_increment / filter->index_inc, data->data_out + filter->out_gen) ;
filter->out_gen += 4 ;
/* Figure out the next index. */
input_index += 1.0 / src_ratio ;
rem = fmod_one (input_index) ;
filter->b_current = (filter->b_current + filter->channels * lrint (input_index - rem)) % filter->b_len ;
input_index = rem ;
} ;
psrc->last_position = input_index ;
/* Save current ratio rather then target ratio. */
psrc->last_ratio = src_ratio ;
data->input_frames_used = filter->in_used / filter->channels ;
data->output_frames_gen = filter->out_gen / filter->channels ;
return SRC_ERR_NO_ERROR ;
} /* sinc_quad_vari_process */
static inline void
calc_output_hex (SINC_FILTER *filter, increment_t increment, increment_t start_filter_index, double scale, float * output)
{ double fraction, left [6], right [6], icoeff ;
increment_t filter_index, max_filter_index ;
int data_index, coeff_count, indx ;
/* Convert input parameters into fixed point. */
max_filter_index = int_to_fp (filter->coeff_half_len) ;
/* First apply the left half of the filter. */
filter_index = start_filter_index ;
coeff_count = (max_filter_index - filter_index) / increment ;
filter_index = filter_index + coeff_count * increment ;
data_index = filter->b_current - filter->channels * coeff_count ;
left [0] = left [1] = left [2] = left [3] = left [4] = left [5] = 0.0 ;
do
{ if (data_index >= 0) /* Avoid underflow access to filter->buffer. */
{ fraction = fp_to_double (filter_index) ;
indx = fp_to_int (filter_index) ;
icoeff = filter->coeffs [indx] + fraction * (filter->coeffs [indx + 1] - filter->coeffs [indx]) ;
left [0] += icoeff * filter->buffer [data_index] ;
left [1] += icoeff * filter->buffer [data_index + 1] ;
left [2] += icoeff * filter->buffer [data_index + 2] ;
left [3] += icoeff * filter->buffer [data_index + 3] ;
left [4] += icoeff * filter->buffer [data_index + 4] ;
left [5] += icoeff * filter->buffer [data_index + 5] ;
} ;
filter_index -= increment ;
data_index = data_index + 6 ;
}
while (filter_index >= MAKE_INCREMENT_T (0)) ;
/* Now apply the right half of the filter. */
filter_index = increment - start_filter_index ;
coeff_count = (max_filter_index - filter_index) / increment ;
filter_index = filter_index + coeff_count * increment ;
data_index = filter->b_current + filter->channels * (1 + coeff_count) ;
right [0] = right [1] = right [2] = right [3] = right [4] = right [5] = 0.0 ;
do
{ fraction = fp_to_double (filter_index) ;
indx = fp_to_int (filter_index) ;
icoeff = filter->coeffs [indx] + fraction * (filter->coeffs [indx + 1] - filter->coeffs [indx]) ;
right [0] += icoeff * filter->buffer [data_index] ;
right [1] += icoeff * filter->buffer [data_index + 1] ;
right [2] += icoeff * filter->buffer [data_index + 2] ;
right [3] += icoeff * filter->buffer [data_index + 3] ;
right [4] += icoeff * filter->buffer [data_index + 4] ;
right [5] += icoeff * filter->buffer [data_index + 5] ;
filter_index -= increment ;
data_index = data_index - 6 ;
}
while (filter_index > MAKE_INCREMENT_T (0)) ;
output [0] = scale * (left [0] + right [0]) ;
output [1] = scale * (left [1] + right [1]) ;
output [2] = scale * (left [2] + right [2]) ;
output [3] = scale * (left [3] + right [3]) ;
output [4] = scale * (left [4] + right [4]) ;
output [5] = scale * (left [5] + right [5]) ;
} /* calc_output_hex */
static int
sinc_hex_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data)
{ SINC_FILTER *filter ;
double input_index, src_ratio, count, float_increment, terminate, rem ;
increment_t increment, start_filter_index ;
int half_filter_chan_len, samples_in_hand ;
if (psrc->private_data == NULL)
return SRC_ERR_NO_PRIVATE ;
filter = (SINC_FILTER*) psrc->private_data ;
/* If there is not a problem, this will be optimised out. */
if (sizeof (filter->buffer [0]) != sizeof (data->data_in [0]))
return SRC_ERR_SIZE_INCOMPATIBILITY ;
filter->in_count = data->input_frames * filter->channels ;
filter->out_count = data->output_frames * filter->channels ;
filter->in_used = filter->out_gen = 0 ;
src_ratio = psrc->last_ratio ;
if (is_bad_src_ratio (src_ratio))
return SRC_ERR_BAD_INTERNAL_STATE ;
/* Check the sample rate ratio wrt the buffer len. */
count = (filter->coeff_half_len + 2.0) / filter->index_inc ;
if (MIN (psrc->last_ratio, data->src_ratio) < 1.0)
count /= MIN (psrc->last_ratio, data->src_ratio) ;
/* Maximum coefficientson either side of center point. */
half_filter_chan_len = filter->channels * (int) (lrint (count) + 1) ;
input_index = psrc->last_position ;
rem = fmod_one (input_index) ;
filter->b_current = (filter->b_current + filter->channels * lrint (input_index - rem)) % filter->b_len ;
input_index = rem ;
terminate = 1.0 / src_ratio + 1e-20 ;
/* Main processing loop. */
while (filter->out_gen < filter->out_count)
{
/* Need to reload buffer? */
samples_in_hand = (filter->b_end - filter->b_current + filter->b_len) % filter->b_len ;
if (samples_in_hand <= half_filter_chan_len)
{ if ((psrc->error = prepare_data (filter, data, half_filter_chan_len)) != 0)
return psrc->error ;
samples_in_hand = (filter->b_end - filter->b_current + filter->b_len) % filter->b_len ;
if (samples_in_hand <= half_filter_chan_len)
break ;
} ;
/* This is the termination condition. */
if (filter->b_real_end >= 0)
{ if (filter->b_current + input_index + terminate >= filter->b_real_end)
break ;
} ;
if (filter->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > 1e-10)
src_ratio = psrc->last_ratio + filter->out_gen * (data->src_ratio - psrc->last_ratio) / filter->out_count ;
float_increment = filter->index_inc * (src_ratio < 1.0 ? src_ratio : 1.0) ;
increment = double_to_fp (float_increment) ;
start_filter_index = double_to_fp (input_index * float_increment) ;
calc_output_hex (filter, increment, start_filter_index, float_increment / filter->index_inc, data->data_out + filter->out_gen) ;
filter->out_gen += 6 ;
/* Figure out the next index. */
input_index += 1.0 / src_ratio ;
rem = fmod_one (input_index) ;
filter->b_current = (filter->b_current + filter->channels * lrint (input_index - rem)) % filter->b_len ;
input_index = rem ;
} ;
psrc->last_position = input_index ;
/* Save current ratio rather then target ratio. */
psrc->last_ratio = src_ratio ;
data->input_frames_used = filter->in_used / filter->channels ;
data->output_frames_gen = filter->out_gen / filter->channels ;
return SRC_ERR_NO_ERROR ;
} /* sinc_hex_vari_process */
static inline void
calc_output_multi (SINC_FILTER *filter, increment_t increment, increment_t start_filter_index, int channels, double scale, float * output)
{ double fraction, icoeff ;
/* The following line is 1999 ISO Standard C. If your compiler complains, get a better compiler. */
double *left, *right ;
increment_t filter_index, max_filter_index ;
int data_index, coeff_count, indx, ch ;
left = filter->left_calc ;
right = filter->right_calc ;
/* Convert input parameters into fixed point. */
max_filter_index = int_to_fp (filter->coeff_half_len) ;
/* First apply the left half of the filter. */
filter_index = start_filter_index ;
coeff_count = (max_filter_index - filter_index) / increment ;
filter_index = filter_index + coeff_count * increment ;
data_index = filter->b_current - channels * coeff_count ;
memset (left, 0, sizeof (left [0]) * channels) ;
do
{ fraction = fp_to_double (filter_index) ;
indx = fp_to_int (filter_index) ;
icoeff = filter->coeffs [indx] + fraction * (filter->coeffs [indx + 1] - filter->coeffs [indx]) ;
if (data_index >= 0) /* Avoid underflow access to filter->buffer. */
{ /*
** Duff's Device.
** See : http://en.wikipedia.org/wiki/Duff's_device
*/
ch = channels ;
do
{ switch (ch % 8)
{ default :
ch -- ;
left [ch] += icoeff * filter->buffer [data_index + ch] ;
/* Falls through. */
case 7 :
ch -- ;
left [ch] += icoeff * filter->buffer [data_index + ch] ;
/* Falls through. */
case 6 :
ch -- ;
left [ch] += icoeff * filter->buffer [data_index + ch] ;
/* Falls through. */
case 5 :
ch -- ;
left [ch] += icoeff * filter->buffer [data_index + ch] ;
/* Falls through. */
case 4 :
ch -- ;
left [ch] += icoeff * filter->buffer [data_index + ch] ;
/* Falls through. */
case 3 :
ch -- ;
left [ch] += icoeff * filter->buffer [data_index + ch] ;
/* Falls through. */
case 2 :
ch -- ;
left [ch] += icoeff * filter->buffer [data_index + ch] ;
/* Falls through. */
case 1 :
ch -- ;
left [ch] += icoeff * filter->buffer [data_index + ch] ;
} ;
}
while (ch > 0) ;
} ;
filter_index -= increment ;
data_index = data_index + channels ;
}
while (filter_index >= MAKE_INCREMENT_T (0)) ;
/* Now apply the right half of the filter. */
filter_index = increment - start_filter_index ;
coeff_count = (max_filter_index - filter_index) / increment ;
filter_index = filter_index + coeff_count * increment ;
data_index = filter->b_current + channels * (1 + coeff_count) ;
memset (right, 0, sizeof (right [0]) * channels) ;
do
{ fraction = fp_to_double (filter_index) ;
indx = fp_to_int (filter_index) ;
icoeff = filter->coeffs [indx] + fraction * (filter->coeffs [indx + 1] - filter->coeffs [indx]) ;
ch = channels ;
do
{
switch (ch % 8)
{ default :
ch -- ;
right [ch] += icoeff * filter->buffer [data_index + ch] ;
/* Falls through. */
case 7 :
ch -- ;
right [ch] += icoeff * filter->buffer [data_index + ch] ;
/* Falls through. */
case 6 :
ch -- ;
right [ch] += icoeff * filter->buffer [data_index + ch] ;
/* Falls through. */
case 5 :
ch -- ;