/* GStreamer

 * Copyright (C) <2007> Sebastian Dröge <slomo@circular-chaos.org>

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library 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

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <glib.h>

#include <math.h>

#include "_kiss_fft_guts_s32.h"

#include "kiss_fftr_s32.h"

#include "gstfft.h"

#include "gstffts32.h"

/**

 * SECTION:gstffts32

 * @title: GstFFTS32

 * @short_description: FFT functions for signed 32 bit integer samples

 *

 * #GstFFTS32 provides a FFT implementation and related functions for

 * signed 32 bit integer samples. To use this call gst_fft_s32_new() for

 * allocating a #GstFFTS32 instance with the appropriate parameters and

 * then call gst_fft_s32_fft() or gst_fft_s32_inverse_fft() to perform the

 * FFT or inverse FFT on a buffer of samples.

 *

 * After use free the #GstFFTS32 instance with gst_fft_s32_free().

 *

 * For the best performance use gst_fft_next_fast_length() to get a

 * number that is entirely a product of 2, 3 and 5 and use this as the

 * @len parameter for gst_fft_s32_new().

 *

 * The @len parameter specifies the number of samples in the time domain that

 * will be processed or generated. The number of samples in the frequency domain

 * is @len/2 + 1. To get n samples in the frequency domain use 2*n - 2 as @len.

 *

 * Before performing the FFT on time domain data it usually makes sense

 * to apply a window function to it. For this gst_fft_s32_window() can comfortably

 * be used.

 *

 * Be aware, that you can't simply run gst_fft_s32_inverse_fft() on the

 * resulting frequency data of gst_fft_s32_fft() to get the original data back.

 * The relation between them is iFFT (FFT (x)) = x / nfft where nfft is the

 * length of the FFT. This also has to be taken into account when calculation

 * the magnitude of the frequency data.

 */

struct _GstFFTS32

{

  void *cfg;

  gboolean inverse;

  gint len;

};

/**

 * gst_fft_s32_new: (skip)

 * @len: Length of the FFT in the time domain

 * @inverse: %TRUE if the #GstFFTS32 instance should be used for the inverse FFT

 *

 * This returns a new #GstFFTS32 instance with the given parameters. It makes

 * sense to keep one instance for several calls for speed reasons.

 *

 * @len must be even and to get the best performance a product of

 * 2, 3 and 5. To get the next number with this characteristics use

 * gst_fft_next_fast_length().

 *

 * Returns: a new #GstFFTS32 instance.

 */

GstFFTS32 *

gst_fft_s32_new (gint len, gboolean inverse)

{

  GstFFTS32 *self;

  gsize subsize = 0, memneeded;

  g_return_val_if_fail (len > 0, NULL);

  g_return_val_if_fail (len % 2 == 0, NULL);

  kiss_fftr_s32_alloc (len, (inverse) ? 1 : 0, NULL, &subsize);

  memneeded = ALIGN_STRUCT (sizeof (GstFFTS32)) + subsize;

  self = (GstFFTS32 *) g_malloc0 (memneeded);

  self->cfg = (((guint8 *) self) + ALIGN_STRUCT (sizeof (GstFFTS32)));

  self->cfg = kiss_fftr_s32_alloc (len, (inverse) ? 1 : 0, self->cfg, &subsize);

  g_assert (self->cfg);

  self->inverse = inverse;

  self->len = len;

  return self;

}

/**

 * gst_fft_s32_fft:

 * @self: #GstFFTS32 instance for this call

 * @timedata: Buffer of the samples in the time domain

 * @freqdata: Target buffer for the samples in the frequency domain

 *

 * This performs the FFT on @timedata and puts the result in @freqdata.

 *

 * @timedata must have as many samples as specified with the @len parameter while

 * allocating the #GstFFTS32 instance with gst_fft_s32_new().

 *

 * @freqdata must be large enough to hold @len/2 + 1 #GstFFTS32Complex frequency

 * domain samples.

 *

 */

void

gst_fft_s32_fft (GstFFTS32 * self, const gint32 * timedata,

    GstFFTS32Complex * freqdata)

{

  g_return_if_fail (self);

  g_return_if_fail (!self->inverse);

  g_return_if_fail (timedata);

  g_return_if_fail (freqdata);

  kiss_fftr_s32 (self->cfg, timedata, (kiss_fft_s32_cpx *) freqdata);

}

/**

 * gst_fft_s32_inverse_fft:

 * @self: #GstFFTS32 instance for this call

 * @freqdata: Buffer of the samples in the frequency domain

 * @timedata: Target buffer for the samples in the time domain

 *

 * This performs the inverse FFT on @freqdata and puts the result in @timedata.

 *

 * @freqdata must have @len/2 + 1 samples, where @len is the parameter specified

 * while allocating the #GstFFTS32 instance with gst_fft_s32_new().

 *

 * @timedata must be large enough to hold @len time domain samples.

 *

 */

void

gst_fft_s32_inverse_fft (GstFFTS32 * self, const GstFFTS32Complex * freqdata,

    gint32 * timedata)

{

  g_return_if_fail (self);

  g_return_if_fail (self->inverse);

  g_return_if_fail (timedata);

  g_return_if_fail (freqdata);

  kiss_fftri_s32 (self->cfg, (kiss_fft_s32_cpx *) freqdata, timedata);

}

/**

 * gst_fft_s32_free:

 * @self: #GstFFTS32 instance for this call

 *

 * This frees the memory allocated for @self.

 *

 */

void

gst_fft_s32_free (GstFFTS32 * self)

{

  g_free (self);

}

/**

 * gst_fft_s32_window:

 * @self: #GstFFTS32 instance for this call

 * @timedata: Time domain samples

 * @window: Window function to apply

 *

 * This calls the window function @window on the @timedata sample buffer.

 *

 */

void

gst_fft_s32_window (GstFFTS32 * self, gint32 * timedata, GstFFTWindow window)

{

  gint i, len;

  g_return_if_fail (self);

  g_return_if_fail (timedata);

  len = self->len;

  switch (window) {

    case GST_FFT_WINDOW_RECTANGULAR:

      /* do nothing */

      break;

    case GST_FFT_WINDOW_HAMMING:

      for (i = 0; i < len; i++)

        timedata[i] *= (0.53836 - 0.46164 * cos (2.0 * G_PI * i / len));

      break;

    case GST_FFT_WINDOW_HANN:

      for (i = 0; i < len; i++)

        timedata[i] *= (0.5 - 0.5 * cos (2.0 * G_PI * i / len));

      break;

    case GST_FFT_WINDOW_BARTLETT:

      for (i = 0; i < len; i++)

        timedata[i] *= (1.0 - fabs ((2.0 * i - len) / len));

      break;

    case GST_FFT_WINDOW_BLACKMAN:

      for (i = 0; i < len; i++)

        timedata[i] *= (0.42 - 0.5 * cos ((2.0 * i) / len) +

            0.08 * cos ((4.0 * i) / len));

      break;

    default:

      g_assert_not_reached ();

      break;

  }

}