/*

 *  Copyright (c) 2015 The WebM project authors. All Rights Reserved.

 *

 *  Use of this source code is governed by a BSD-style license

 *  that can be found in the LICENSE file in the root of the source

 *  tree. An additional intellectual property rights grant can be found

 *  in the file PATENTS.  All contributing project authors may

 *  be found in the AUTHORS file in the root of the source tree.

 */

#include <math.h>

#include <stdlib.h>

#include "./vpx_config.h"

#include "./vpx_dsp_rtcd.h"

#include "vpx/vpx_integer.h"

#include "vpx_dsp/postproc.h"

#include "vpx_ports/mem.h"

void vpx_plane_add_noise_c(uint8_t *start, const int8_t *noise, int blackclamp,

                           int whiteclamp, int width, int height, int pitch) {

  int i, j;

  int bothclamp = blackclamp + whiteclamp;

  for (i = 0; i < height; ++i) {

    uint8_t *pos = start + i * pitch;

    const int8_t *ref = (const int8_t *)(noise + (rand() & 0xff));  // NOLINT

    for (j = 0; j < width; ++j) {

      int v = pos[j];

      v = clamp(v - blackclamp, 0, 255);

      v = clamp(v + bothclamp, 0, 255);

      v = clamp(v - whiteclamp, 0, 255);

      pos[j] = v + ref[j];

    }

  }

}

static double gaussian(double sigma, double mu, double x) {

  return 1 / (sigma * sqrt(2.0 * 3.14159265)) *

         (exp(-(x - mu) * (x - mu) / (2 * sigma * sigma)));

}

int vpx_setup_noise(double sigma, int8_t *noise, int size) {

  int8_t char_dist[256];

  int next = 0, i, j;

  // set up a 256 entry lookup that matches gaussian distribution

  for (i = -32; i < 32; ++i) {

    const int a_i = (int)(0.5 + 256 * gaussian(sigma, 0, i));

    if (a_i) {

      for (j = 0; j < a_i; ++j) {

        if (next + j >= 256) goto set_noise;

        char_dist[next + j] = (int8_t)i;

      }

      next = next + j;

    }

  }

  // Rounding error - might mean we have less than 256.

  for (; next < 256; ++next) {

    char_dist[next] = 0;

  }

set_noise:

  for (i = 0; i < size; ++i) {

    noise[i] = char_dist[rand() & 0xff];  // NOLINT

  }

  // Returns the highest non 0 value used in distribution.

  return -char_dist[0];

}