/**
 *
 * \section COPYRIGHT
 *
 * Copyright 2013-2014 The libLTE Developers. See the
 * COPYRIGHT file at the top-level directory of this distribution.
 *
 * \section LICENSE
 *
 * This file is part of the libLTE library.
 *
 * libLTE is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * libLTE 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 Lesser General Public License for more details.
 *
 * A copy of the GNU Lesser General Public License can be found in
 * the LICENSE file in the top-level directory of this distribution
 * and at http://www.gnu.org/licenses/.
 *
 */


#include <stdlib.h>
#include <string.h>

#include "liblte/phy/utils/dft.h"
#include "liblte/phy/utils/vector.h"
#include "liblte/phy/utils/convolution.h"


int conv_fft_cc_init(conv_fft_cc_t *state, int input_len, int filter_len) {
  state->input_len = input_len;
  state->filter_len = filter_len;
  state->output_len = input_len+filter_len-1;
  state->input_fft = vec_malloc(sizeof(_Complex float)*state->output_len);
  state->filter_fft = vec_malloc(sizeof(_Complex float)*state->output_len);
  state->output_fft = vec_malloc(sizeof(_Complex float)*state->output_len);
  if (!state->input_fft || !state->filter_fft || !state->output_fft) {
    return -1;
  }
  if (dft_plan(&state->input_plan,state->output_len,FORWARD,COMPLEX)) {
    return -2;
  }
  if (dft_plan(&state->filter_plan,state->output_len,FORWARD,COMPLEX)) {
    return -3;
  }
  if (dft_plan(&state->output_plan,state->output_len,BACKWARD,COMPLEX)) {
    return -4;
  }
  return 0;
}

void conv_fft_cc_free(conv_fft_cc_t *state) {
  if (state->input_fft) {
    free(state->input_fft);
  }
  if (state->filter_fft) {
    free(state->filter_fft);
  }
  if (state->output_fft) {
    free(state->output_fft);
  }
  dft_plan_free(&state->input_plan);
  dft_plan_free(&state->filter_plan);
  dft_plan_free(&state->output_plan);
}

int conv_fft_cc_run(conv_fft_cc_t *state, _Complex float *input, _Complex float *filter, _Complex float *output) {

  dft_run_c(&state->input_plan, input, state->input_fft);
  dft_run_c(&state->filter_plan, filter, state->filter_fft);

  vec_prod_ccc(state->input_fft,state->filter_fft,state->output_fft,state->output_len);

  dft_run_c(&state->output_plan, state->output_fft, output);

  return state->output_len;

}

int conv_cc(_Complex float *input, _Complex float *filter, _Complex float *output, int input_len, int filter_len) {
  int i,j;
  int output_len;
  output_len=input_len+filter_len-1;
  memset(output,0,output_len*sizeof(_Complex float));
  for (i=0;i<input_len;i++) {
    for (j=0;j<filter_len;j++) {
      output[i+j]+=input[i]*filter[j];
    }
  }
  return output_len;
}