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 "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; 18 static inline int64_t sk_64_mul(int64_t a, int64_t b) { 19 return a * b; 20 } 21 22 /////////////////////////////////////////////////////////////////////////////// 23 24 /** Given an integer and a positive (max) integer, return the value 25 * pinned against 0 and max, inclusive. 26 * @param value The value we want returned pinned between [0...max] 27 * @param max The positive max value 28 * @return 0 if value < 0, max if value > max, else value 29 */ 30 static inline int SkClampMax(int value, int max) { 31 // ensure that max is positive 32 SkASSERT(max >= 0); 33 if (value < 0) { 34 value = 0; 35 } 36 if (value > max) { 37 value = max; 38 } 39 return value; 40 } 41 42 /** 43 * Returns true if value is a power of 2. Does not explicitly check for 44 * value <= 0. 45 */ 46 template <typename T> constexpr inline bool SkIsPow2(T value) { 47 return (value & (value - 1)) == 0; 48 } 49 50 /////////////////////////////////////////////////////////////////////////////// 51 52 /** 53 * Return a*b/((1 << shift) - 1), rounding any fractional bits. 54 * Only valid if a and b are unsigned and <= 32767 and shift is > 0 and <= 8 55 */ 56 static inline unsigned SkMul16ShiftRound(U16CPU a, U16CPU b, int shift) { 57 SkASSERT(a <= 32767); 58 SkASSERT(b <= 32767); 59 SkASSERT(shift > 0 && shift <= 8); 60 unsigned prod = a*b + (1 << (shift - 1)); 61 return (prod + (prod >> shift)) >> shift; 62 } 63 64 /** 65 * Return a*b/255, rounding any fractional bits. 66 * Only valid if a and b are unsigned and <= 32767. 67 */ 68 static inline U8CPU SkMulDiv255Round(U16CPU a, U16CPU b) { 69 SkASSERT(a <= 32767); 70 SkASSERT(b <= 32767); 71 unsigned prod = a*b + 128; 72 return (prod + (prod >> 8)) >> 8; 73 } 74 75 #endif 76
