1/*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef SkMath_DEFINED
9#define SkMath_DEFINED
10
11#include "include/core/SkTypes.h"
12
13// 64bit -> 32bit utilities
14
15// Handy util that can be passed two ints, and will automatically promote to
16// 64bits before the multiply, so the caller doesn't have to remember to cast
17// e.g. (int64_t)a * b;
18static inline int64_t sk_64_mul(int64_t a, int64_t b) {
19 return a * b;
20}
21
22///////////////////////////////////////////////////////////////////////////////
23
24/**
25 * Returns true if value is a power of 2. Does not explicitly check for
26 * value <= 0.
27 */
28template <typename T> constexpr inline bool SkIsPow2(T value) {
29 return (value & (value - 1)) == 0;
30}
31
32///////////////////////////////////////////////////////////////////////////////
33
34/**
35 * Return a*b/((1 << shift) - 1), rounding any fractional bits.
36 * Only valid if a and b are unsigned and <= 32767 and shift is > 0 and <= 8
37 */
38static inline unsigned SkMul16ShiftRound(U16CPU a, U16CPU b, int shift) {
39 SkASSERT(a <= 32767);
40 SkASSERT(b <= 32767);
41 SkASSERT(shift > 0 && shift <= 8);
42 unsigned prod = a*b + (1 << (shift - 1));
43 return (prod + (prod >> shift)) >> shift;
44}
45
46/**
47 * Return a*b/255, rounding any fractional bits.
48 * Only valid if a and b are unsigned and <= 32767.
49 */
50static inline U8CPU SkMulDiv255Round(U16CPU a, U16CPU b) {
51 SkASSERT(a <= 32767);
52 SkASSERT(b <= 32767);
53 unsigned prod = a*b + 128;
54 return (prod + (prod >> 8)) >> 8;
55}
56
57#endif
58