variance_c.c

/*
 *  Copyright (c) 2010 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 "variance.h"
#include "vp8/common/filter.h"


unsigned int vp8_get_mb_ss_c
(
  const short *src_ptr
) {
  unsigned int i = 0, sum = 0;

  do {
    sum += (src_ptr[i] * src_ptr[i]);
    i++;
  } while (i < 256);

  return sum;
}


static void variance(
  const unsigned char *src_ptr,
  int  source_stride,
  const unsigned char *ref_ptr,
  int  recon_stride,
  int  w,
  int  h,
  unsigned int *sse,
  int *sum) {
  int i, j;
  int diff;

  *sum = 0;
  *sse = 0;

  for (i = 0; i < h; i++) {
    for (j = 0; j < w; j++) {
      diff = src_ptr[j] - ref_ptr[j];
      *sum += diff;
      *sse += diff * diff;
    }

    src_ptr += source_stride;
    ref_ptr += recon_stride;
  }
}

#if CONFIG_SUPERBLOCKS
unsigned int vp8_variance32x32_c(const unsigned char *src_ptr,
                                 int  source_stride,
                                 const unsigned char *ref_ptr,
                                 int  recon_stride,
                                 unsigned int *sse) {
  unsigned int var;
  int avg;

  variance(src_ptr, source_stride, ref_ptr, recon_stride, 32, 32, &var, &avg);
  *sse = var;
  return (var - ((avg * avg) >> 10));
}