libvpx: Add VP9 decoder.

source/libvpx/vp9/common/vp9_subpelvar.h

+/*
+ *  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 "vp9/common/vp9_filter.h"
+
+
+
+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;
+  }
+}
+
+/****************************************************************************
+ *
+ *  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  *vp9_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 VP9_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 *vp9_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]          * vp9_filter[0]) +
+                       ((int)src_ptr[pixel_step] * vp9_filter[1]) +
+                       (VP9_FILTER_WEIGHT / 2)) >> VP9_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  *vp9_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 VP9_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 *vp9_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]         * vp9_filter[0]) +
+             ((int)src_ptr[pixel_step] * vp9_filter[1]) +
+             (VP9_FILTER_WEIGHT / 2);
+      output_ptr[j] = (unsigned int)(Temp >> VP9_FILTER_SHIFT);
+      src_ptr++;
+    }
+
+    // Next row...
+    src_ptr    += src_pixels_per_line - output_width;
+    output_ptr += output_width;
+  }
+}
+