v_frame/
math.rs

1// Copyright (c) 2017-2020, The rav1e contributors. All rights reserved
2//
3// This source code is subject to the terms of the BSD 2 Clause License and
4// the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
5// was not distributed with this source code in the LICENSE file, you can
6// obtain it at www.aomedia.org/license/software. If the Alliance for Open
7// Media Patent License 1.0 was not distributed with this source code in the
8// PATENTS file, you can obtain it at www.aomedia.org/license/patent.
9
10use num_traits::PrimInt;
11use std::mem::size_of;
12
13pub trait Fixed {
14    fn floor_log2(&self, n: usize) -> usize;
15    fn ceil_log2(&self, n: usize) -> usize;
16    fn align_power_of_two(&self, n: usize) -> usize;
17    fn align_power_of_two_and_shift(&self, n: usize) -> usize;
18}
19
20impl Fixed for usize {
21    #[inline]
22    fn floor_log2(&self, n: usize) -> usize {
23        self & !((1 << n) - 1)
24    }
25    #[inline]
26    fn ceil_log2(&self, n: usize) -> usize {
27        (self + (1 << n) - 1).floor_log2(n)
28    }
29    #[inline]
30    fn align_power_of_two(&self, n: usize) -> usize {
31        self.ceil_log2(n)
32    }
33    #[inline]
34    fn align_power_of_two_and_shift(&self, n: usize) -> usize {
35        (self + (1 << n) - 1) >> n
36    }
37}
38
39pub fn clamp<T: PartialOrd>(input: T, min: T, max: T) -> T {
40    if input < min {
41        min
42    } else if input > max {
43        max
44    } else {
45        input
46    }
47}
48
49pub trait ILog: PrimInt {
50    // Integer binary logarithm of an integer value.
51    // Returns floor(log2(self)) + 1, or 0 if self == 0.
52    // This is the number of bits that would be required to represent self in two's
53    //  complement notation with all of the leading zeros stripped.
54    // TODO: Mark const once trait functions can be constant
55    fn ilog(self) -> usize {
56        size_of::<Self>() * 8 - self.leading_zeros() as usize
57    }
58}
59
60impl<T> ILog for T where T: PrimInt {}
61
62#[inline(always)]
63pub fn msb(x: i32) -> i32 {
64    debug_assert!(x > 0);
65    31 ^ (x.leading_zeros() as i32)
66}
67
68#[inline(always)]
69pub const fn round_shift(value: i32, bit: usize) -> i32 {
70    (value + (1 << bit >> 1)) >> bit
71}
72
73#[cfg(test)]
74mod tests {
75    use super::*;
76
77    #[test]
78    fn test_floor_log2() {
79        assert_eq!(123usize.floor_log2(4), 112);
80        assert_eq!(16usize.floor_log2(4), 16);
81        assert_eq!(0usize.floor_log2(4), 0);
82    }
83
84    #[test]
85    fn test_ceil_log2() {
86        assert_eq!(123usize.ceil_log2(4), 128);
87        assert_eq!(16usize.ceil_log2(4), 16);
88        assert_eq!(0usize.ceil_log2(4), 0);
89    }
90
91    #[test]
92    fn test_align_power_of_two() {
93        assert_eq!(123usize.align_power_of_two(4), 128);
94        assert_eq!(16usize.align_power_of_two(4), 16);
95        assert_eq!(0usize.align_power_of_two(4), 0);
96    }
97
98    #[test]
99    fn test_align_power_of_two_and_shift() {
100        assert_eq!(123usize.align_power_of_two_and_shift(4), 8);
101        assert_eq!(16usize.align_power_of_two_and_shift(4), 1);
102        assert_eq!(0usize.align_power_of_two_and_shift(4), 0);
103    }
104
105    #[test]
106    fn test_clamp() {
107        assert_eq!(clamp(5, 0, 10), 5);
108        assert_eq!(clamp(-1, 0, 10), 0);
109        assert_eq!(clamp(11, 0, 10), 10);
110    }
111
112    #[test]
113    fn test_ilog() {
114        assert_eq!(ILog::ilog(0i32), 0);
115        assert_eq!(ILog::ilog(1i32), 1);
116        assert_eq!(ILog::ilog(2i32), 2);
117        assert_eq!(ILog::ilog(3i32), 2);
118        assert_eq!(ILog::ilog(4i32), 3);
119    }
120
121    #[test]
122    fn test_msb() {
123        assert_eq!(msb(1), 0);
124        assert_eq!(msb(2), 1);
125        assert_eq!(msb(3), 1);
126        assert_eq!(msb(4), 2);
127    }
128
129    #[test]
130    fn test_round_shift() {
131        assert_eq!(round_shift(7, 2), 2);
132        assert_eq!(round_shift(8, 2), 2);
133        assert_eq!(round_shift(9, 2), 2);
134        assert_eq!(round_shift(10, 2), 3);
135    }
136}
v_frame/math.rs

v_frame/
math.rs
