/*
 *  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 "./vp8_rtcd.h"
#include "filter.h"
#include "variance.h"

/* This is a bad idea.
 * ctz = count trailing zeros */
static int ctz(int a) {
  int b = 0;
  while (a != 1) {
    a >>= 1;
    b++;
  }
  return b;
}

static unsigned int 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 i, j;
    int diff, sum;

    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;
    }

    return (*sse - (((unsigned int)sum * sum) >> (int)((ctz(w) + ctz(h)))));
}

/****************************************************************************
 *
 *  ROUTINE       : filter_block2d_bil_first_pass
 *
 *  INPUTS        : UINT8  *src_ptr          : Pointer to source block.
 *                  UINT32 src_pixels_per_line : Stride of input block.
 *                  UINT32 pixel_step        : Offset between filter input samples (see notes).
 *                  UINT32 output_height     : Input block height.
 *                  UINT32 output_width      : Input block width.
 *                  INT32  *vp8_filter          : Array of 2 bi-linear filter taps.
 *
 *  OUTPUTS       : INT32 *output_ptr        : Pointer to filtered block.
 *
 *  RETURNS       : void
 *
 *  FUNCTION      : Applies a 1-D 2-tap bi-linear filter to the source block in
 *                  either horizontal or vertical direction to produce the
 *                  filtered output block. Used to implement first-pass
 *                  of 2-D separable filter.
 *
 *  SPECIAL NOTES : Produces INT32 output to retain precision for next pass.
 *                  Two filter taps should sum to VP8_FILTER_WEIGHT.
 *                  pixel_step defines whether the filter is applied
 *                  horizontally (pixel_step=1) or vertically (pixel_step=stride).
 *                  It defines the offset required to move from one input
 *                  to the next.
 *
 ****************************************************************************/
static void var_filter_block2d_bil_first_pass
(
    const unsigned char *src_ptr,
    unsigned short *output_ptr,
    unsigned int src_pixels_per_line,
    int pixel_step,
    unsigned int output_height,
    unsigned int output_width,
    const short *vp8_filter
)
{
    unsigned int i, j;

    for (i = 0; i < output_height; i++)
    {
        for (j = 0; j < output_width; j++)
        {
            /* Apply bilinear filter */
            output_ptr[j] = (((int)src_ptr[0]          * vp8_filter[0]) +
                             ((int)src_ptr[pixel_step] * vp8_filter[1]) +
                             (VP8_FILTER_WEIGHT / 2)) >> VP8_FILTER_SHIFT;
            src_ptr++;
        }

        /* Next row... */
        src_ptr    += src_pixels_per_line - output_width;
        output_ptr += output_width;
    }
}

/****************************************************************************
 *
 *  ROUTINE       : filter_block2d_bil_second_pass
 *
 *  INPUTS        : INT32  *src_ptr          : Pointer to source block.
 *                  UINT32 src_pixels_per_line : Stride of input block.
 *                  UINT32 pixel_step        : Offset between filter input samples (see notes).
 *                  UINT32 output_height     : Input block height.
 *                  UINT32 output_width      : Input block width.
 *                  INT32  *vp8_filter          : Array of 2 bi-linear filter taps.
 *
 *  OUTPUTS       : UINT16 *output_ptr       : Pointer to filtered block.
 *
 *  RETURNS       : void
 *
 *  FUNCTION      : Applies a 1-D 2-tap bi-linear filter to the source block in
 *                  either horizontal or vertical direction to produce the
 *                  filtered output block. Used to implement second-pass
 *                  of 2-D separable filter.
 *
 *  SPECIAL NOTES : Requires 32-bit input as produced by filter_block2d_bil_first_pass.
 *                  Two filter taps should sum to VP8_FILTER_WEIGHT.
 *                  pixel_step defines whether the filter is applied
 *                  horizontally (pixel_step=1) or vertically (pixel_step=stride).
 *                  It defines the offset required to move from one input
 *                  to the next.
 *
 ****************************************************************************/
static void var_filter_block2d_bil_second_pass
(
    const unsigned short *src_ptr,
    unsigned char  *output_ptr,
    unsigned int  src_pixels_per_line,
    unsigned int  pixel_step,
    unsigned int  output_height,
    unsigned int  output_width,
    const short *vp8_filter
)
{
    unsigned int  i, j;
    int  Temp;

    for (i = 0; i < output_height; i++)
    {
        for (j = 0; j < output_width; j++)
        {
            /* Apply filter */
            Temp = ((int)src_ptr[0]          * vp8_filter[0]) +
                   ((int)src_ptr[pixel_step] * vp8_filter[1]) +
                   (VP8_FILTER_WEIGHT / 2);
            output_ptr[j] = (unsigned int)(Temp >> VP8_FILTER_SHIFT);
            src_ptr++;
        }

        /* Next row... */
        src_ptr    += src_pixels_per_line - output_width;
        output_ptr += output_width;
    }
}


unsigned int vp8_sub_pixel_variance4x4_c
(
    const unsigned char  *src_ptr,
    int  src_pixels_per_line,
    int  xoffset,
    int  yoffset,
    const unsigned char *dst_ptr,
    int dst_pixels_per_line,
    unsigned int *sse
)
{
    unsigned char  temp2[20*16];
    const short *HFilter, *VFilter;
    unsigned short FData3[5*4]; /* Temp data bufffer used in filtering */

    HFilter = vp8_bilinear_filters[xoffset];
    VFilter = vp8_bilinear_filters[yoffset];

    /* First filter 1d Horizontal */
    var_filter_block2d_bil_first_pass(src_ptr, FData3, src_pixels_per_line, 1, 5, 4, HFilter);

    /* Now filter Verticaly */
    var_filter_block2d_bil_second_pass(FData3, temp2, 4,  4,  4,  4, VFilter);

    return variance(temp2, 4, dst_ptr, dst_pixels_per_line, 4, 4, sse);
}


unsigned int vp8_sub_pixel_variance8x8_c
(
    const unsigned char  *src_ptr,
    int  src_pixels_per_line,
    int  xoffset,
    int  yoffset,
    const unsigned char *dst_ptr,
    int dst_pixels_per_line,
    unsigned int *sse
)
{
    unsigned short FData3[9*8]; /* Temp data bufffer used in filtering */
    unsigned char  temp2[20*16];
    const short *HFilter, *VFilter;

    HFilter = vp8_bilinear_filters[xoffset];
    VFilter = vp8_bilinear_filters[yoffset];

    var_filter_block2d_bil_first_pass(src_ptr, FData3, src_pixels_per_line, 1, 9, 8, HFilter);
    var_filter_block2d_bil_second_pass(FData3, temp2, 8, 8, 8, 8, VFilter);

    return variance(temp2, 8, dst_ptr, dst_pixels_per_line, 8, 8, sse);
}

unsigned int vp8_sub_pixel_variance16x16_c
(
    const unsigned char  *src_ptr,
    int  src_pixels_per_line,
    int  xoffset,
    int  yoffset,
    const unsigned char *dst_ptr,
    int dst_pixels_per_line,
    unsigned int *sse
)
{
    unsigned short FData3[17*16];   /* Temp data bufffer used in filtering */
    unsigned char  temp2[20*16];
    const short *HFilter, *VFilter;

    HFilter = vp8_bilinear_filters[xoffset];
    VFilter = vp8_bilinear_filters[yoffset];

    var_filter_block2d_bil_first_pass(src_ptr, FData3, src_pixels_per_line, 1, 17, 16, HFilter);
    var_filter_block2d_bil_second_pass(FData3, temp2, 16, 16, 16, 16, VFilter);

    return variance(temp2, 16, dst_ptr, dst_pixels_per_line, 16, 16, sse);
}


unsigned int vp8_variance_halfpixvar16x16_h_c(
    const unsigned char *src_ptr,
    int  source_stride,
    const unsigned char *ref_ptr,
    int  recon_stride,
    unsigned int *sse)
{
    return vp8_sub_pixel_variance16x16_c(src_ptr, source_stride, 4, 0,
                                         ref_ptr, recon_stride, sse);
}


unsigned int vp8_variance_halfpixvar16x16_v_c(
    const unsigned char *src_ptr,
    int  source_stride,
    const unsigned char *ref_ptr,
    int  recon_stride,
    unsigned int *sse)
{
    return vp8_sub_pixel_variance16x16_c(src_ptr, source_stride, 0, 4,
                                         ref_ptr, recon_stride, sse);
}


unsigned int vp8_variance_halfpixvar16x16_hv_c(
    const unsigned char *src_ptr,
    int  source_stride,
    const unsigned char *ref_ptr,
    int  recon_stride,
    unsigned int *sse)
{
    return vp8_sub_pixel_variance16x16_c(src_ptr, source_stride, 4, 4,
                                         ref_ptr, recon_stride, sse);
}


unsigned int vp8_sub_pixel_variance16x8_c
(
    const unsigned char  *src_ptr,
    int  src_pixels_per_line,
    int  xoffset,
    int  yoffset,
    const unsigned char *dst_ptr,
    int dst_pixels_per_line,
    unsigned int *sse
)
{
    unsigned short FData3[16*9];    /* Temp data bufffer used in filtering */
    unsigned char  temp2[20*16];
    const short *HFilter, *VFilter;

    HFilter = vp8_bilinear_filters[xoffset];
    VFilter = vp8_bilinear_filters[yoffset];

    var_filter_block2d_bil_first_pass(src_ptr, FData3, src_pixels_per_line, 1, 9, 16, HFilter);
    var_filter_block2d_bil_second_pass(FData3, temp2, 16, 16, 8, 16, VFilter);

    return variance(temp2, 16, dst_ptr, dst_pixels_per_line, 16, 8, sse);
}

unsigned int vp8_sub_pixel_variance8x16_c
(
    const unsigned char  *src_ptr,
    int  src_pixels_per_line,
    int  xoffset,
    int  yoffset,
    const unsigned char *dst_ptr,
    int dst_pixels_per_line,
    unsigned int *sse
)
{
    unsigned short FData3[9*16];    /* Temp data bufffer used in filtering */
    unsigned char  temp2[20*16];
    const short *HFilter, *VFilter;


    HFilter = vp8_bilinear_filters[xoffset];
    VFilter = vp8_bilinear_filters[yoffset];


    var_filter_block2d_bil_first_pass(src_ptr, FData3, src_pixels_per_line, 1, 17, 8, HFilter);
    var_filter_block2d_bil_second_pass(FData3, temp2, 8, 8, 16, 8, VFilter);

    return variance(temp2, 8, dst_ptr, dst_pixels_per_line, 8, 16, sse);
}