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      1 /*
      2  *  Copyright (c) 2011 The WebM project authors. All Rights Reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #ifndef VP9_COMMON_VP9_FILTER_H_
     12 #define VP9_COMMON_VP9_FILTER_H_
     13 
     14 #include "./vpx_config.h"
     15 #include "vpx/vpx_integer.h"
     16 
     17 #define FILTER_BITS 7
     18 
     19 #define SUBPEL_BITS 4
     20 #define SUBPEL_MASK ((1 << SUBPEL_BITS) - 1)
     21 #define SUBPEL_SHIFTS (1 << SUBPEL_BITS)
     22 #define SUBPEL_TAPS 8
     23 
     24 typedef enum {
     25   EIGHTTAP = 0,
     26   EIGHTTAP_SMOOTH = 1,
     27   EIGHTTAP_SHARP = 2,
     28   BILINEAR = 3,
     29   SWITCHABLE = 4  /* should be the last one */
     30 } INTERPOLATION_TYPE;
     31 
     32 typedef int16_t subpel_kernel[SUBPEL_TAPS];
     33 
     34 struct subpix_fn_table {
     35   const subpel_kernel *filter_x;
     36   const subpel_kernel *filter_y;
     37 };
     38 
     39 const subpel_kernel *vp9_get_filter_kernel(INTERPOLATION_TYPE type);
     40 
     41 extern const subpel_kernel vp9_bilinear_filters[SUBPEL_SHIFTS];
     42 extern const subpel_kernel vp9_sub_pel_filters_8[SUBPEL_SHIFTS];
     43 extern const subpel_kernel vp9_sub_pel_filters_8s[SUBPEL_SHIFTS];
     44 extern const subpel_kernel vp9_sub_pel_filters_8lp[SUBPEL_SHIFTS];
     45 
     46 // The VP9_BILINEAR_FILTERS_2TAP macro returns a pointer to the bilinear
     47 // filter kernel as a 2 tap filter.
     48 #define BILINEAR_FILTERS_2TAP(x) \
     49   (vp9_bilinear_filters[(x)] + SUBPEL_TAPS/2 - 1)
     50 
     51 #endif  // VP9_COMMON_VP9_FILTER_H_
     52