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76 lines
2.1 KiB
76 lines
2.1 KiB
4 months ago
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/*
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* Copyright 2006 The Android Open Source Project
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkMath_DEFINED
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#define SkMath_DEFINED
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#include "SkTypes.h"
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// 64bit -> 32bit utilities
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// Handy util that can be passed two ints, and will automatically promote to
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// 64bits before the multiply, so the caller doesn't have to remember to cast
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// e.g. (int64_t)a * b;
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static inline int64_t sk_64_mul(int64_t a, int64_t b) {
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return a * b;
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}
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///////////////////////////////////////////////////////////////////////////////
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/** Given an integer and a positive (max) integer, return the value
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* pinned against 0 and max, inclusive.
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* @param value The value we want returned pinned between [0...max]
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* @param max The positive max value
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* @return 0 if value < 0, max if value > max, else value
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*/
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static inline int SkClampMax(int value, int max) {
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// ensure that max is positive
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SkASSERT(max >= 0);
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if (value < 0) {
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value = 0;
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}
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if (value > max) {
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value = max;
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}
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return value;
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}
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/**
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* Returns true if value is a power of 2. Does not explicitly check for
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* value <= 0.
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*/
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template <typename T> constexpr inline bool SkIsPow2(T value) {
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return (value & (value - 1)) == 0;
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}
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///////////////////////////////////////////////////////////////////////////////
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/**
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* Return a*b/((1 << shift) - 1), rounding any fractional bits.
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* Only valid if a and b are unsigned and <= 32767 and shift is > 0 and <= 8
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*/
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static inline unsigned SkMul16ShiftRound(U16CPU a, U16CPU b, int shift) {
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SkASSERT(a <= 32767);
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SkASSERT(b <= 32767);
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SkASSERT(shift > 0 && shift <= 8);
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unsigned prod = a*b + (1 << (shift - 1));
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return (prod + (prod >> shift)) >> shift;
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}
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/**
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* Return a*b/255, rounding any fractional bits.
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* Only valid if a and b are unsigned and <= 32767.
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*/
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static inline U8CPU SkMulDiv255Round(U16CPU a, U16CPU b) {
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SkASSERT(a <= 32767);
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SkASSERT(b <= 32767);
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unsigned prod = a*b + 128;
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return (prod + (prod >> 8)) >> 8;
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}
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#endif
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