1 /*
2 * Copyright (c) 2018, Alliance for Open Media. All rights reserved
3 *
4 * This source code is subject to the terms of the BSD 2 Clause License and
5 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
6 * was not distributed with this source code in the LICENSE file, you can
7 * obtain it at www.aomedia.org/license/software. If the Alliance for Open
8 * Media Patent License 1.0 was not distributed with this source code in the
9 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
10 */
11
12 #ifndef AOM_AOM_DSP_RECENTER_H_
13 #define AOM_AOM_DSP_RECENTER_H_
14
15 #include "config/aom_config.h"
16
17 #include "aom/aom_integer.h"
18
19 // Inverse recenters a non-negative literal v around a reference r
inv_recenter_nonneg(uint16_t r,uint16_t v)20 static INLINE uint16_t inv_recenter_nonneg(uint16_t r, uint16_t v) {
21 if (v > (r << 1))
22 return v;
23 else if ((v & 1) == 0)
24 return (v >> 1) + r;
25 else
26 return r - ((v + 1) >> 1);
27 }
28
29 // Inverse recenters a non-negative literal v in [0, n-1] around a
30 // reference r also in [0, n-1]
inv_recenter_finite_nonneg(uint16_t n,uint16_t r,uint16_t v)31 static INLINE uint16_t inv_recenter_finite_nonneg(uint16_t n, uint16_t r,
32 uint16_t v) {
33 if ((r << 1) <= n) {
34 return inv_recenter_nonneg(r, v);
35 } else {
36 return n - 1 - inv_recenter_nonneg(n - 1 - r, v);
37 }
38 }
39
40 // Recenters a non-negative literal v around a reference r
recenter_nonneg(uint16_t r,uint16_t v)41 static INLINE uint16_t recenter_nonneg(uint16_t r, uint16_t v) {
42 if (v > (r << 1))
43 return v;
44 else if (v >= r)
45 return ((v - r) << 1);
46 else
47 return ((r - v) << 1) - 1;
48 }
49
50 // Recenters a non-negative literal v in [0, n-1] around a
51 // reference r also in [0, n-1]
recenter_finite_nonneg(uint16_t n,uint16_t r,uint16_t v)52 static INLINE uint16_t recenter_finite_nonneg(uint16_t n, uint16_t r,
53 uint16_t v) {
54 if ((r << 1) <= n) {
55 return recenter_nonneg(r, v);
56 } else {
57 return recenter_nonneg(n - 1 - r, n - 1 - v);
58 }
59 }
60
61 #endif // AOM_AOM_DSP_RECENTER_H_
62