SkMathPriv.h | Explore in Territory

/*
 * Copyright 2012 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkMathPriv_DEFINED
#define SkMathPriv_DEFINED

#include "include/private/base/SkAssert.h"
#include "include/private/base/SkCPUTypes.h"
#include "include/private/base/SkTemplates.h"

#include <cstddef>
#include <cstdint>

/**
 *  Return the integer square root of value, with a bias of bitBias
 */
int32_t SkSqrtBits(int32_t value, int bitBias);

/** Return the integer square root of n, treated as a SkFixed (16.16)
 */
static inline int32_t SkSqrt32(int32_t n) { … }

/**
 *  Returns (value < 0 ? 0 : value) efficiently (i.e. no compares or branches)
 */
static inline int SkClampPos(int value) { … }

/**
 * Stores numer/denom and numer%denom into div and mod respectively.
 */
template <typename In, typename Out>
inline void SkTDivMod(In numer, In denom, Out* div, Out* mod) { … }

/** Returns -1 if n < 0, else returns 0
 */
#define SkExtractSign(n) …

/** If sign == -1, returns -n, else sign must be 0, and returns n.
 Typically used in conjunction with SkExtractSign().
 */
static inline int32_t SkApplySign(int32_t n, int32_t sign) { … }

/** Return x with the sign of y */
static inline int32_t SkCopySign32(int32_t x, int32_t y) { … }

/** Given a positive value and a positive max, return the value
 pinned against max.
 Note: only works as long as max - value doesn't wrap around
 @return max if value >= max, else value
 */
static inline unsigned SkClampUMax(unsigned value, unsigned max) { … }

// If a signed int holds min_int (e.g. 0x80000000) it is undefined what happens when
// we negate it (even though we *know* we're 2's complement and we'll get the same
// value back). So we create this helper function that casts to size_t (unsigned) first,
// to avoid the complaint.
static inline size_t sk_negate_to_size_t(int32_t value) { … }

///////////////////////////////////////////////////////////////////////////////

/** Return a*b/255, truncating away any fractional bits. Only valid if both
 a and b are 0..255
 */
static inline U8CPU SkMulDiv255Trunc(U8CPU a, U8CPU b) { … }

/** Return (a*b)/255, taking the ceiling of any fractional bits. Only valid if
 both a and b are 0..255. The expected result equals (a * b + 254) / 255.
 */
static inline U8CPU SkMulDiv255Ceiling(U8CPU a, U8CPU b) { … }

/** Just the rounding step in SkDiv255Round: round(value / 255)
 */
static inline unsigned SkDiv255Round(unsigned prod) { … }

/**
 * Swap byte order of a 4-byte value, e.g. 0xaarrggbb -> 0xbbggrraa.
 */
#if defined(_MSC_VER)
    #include <stdlib.h>
    static inline uint32_t SkBSwap32(uint32_t v) { return _byteswap_ulong(v); }
#else
    static inline uint32_t SkBSwap32(uint32_t v) { … }
#endif

/*
 * Return the number of set bits (i.e., the population count) in the provided uint32_t.
 */
int SkPopCount_portable(uint32_t n);

#if defined(__GNUC__) || defined(__clang__)
    static inline int SkPopCount(uint32_t n) { … }
#else
    static inline int SkPopCount(uint32_t n) {
        return SkPopCount_portable(n);
    }
#endif

/*
 * Return the 0-based index of the nth bit set in target
 * Returns 32 if there is no nth bit set.
 */
int SkNthSet(uint32_t target, int n);

//! Returns the number of leading zero bits (0...32)
// From Hacker's Delight 2nd Edition
constexpr int SkCLZ_portable(uint32_t x) { … }

static_assert …;
static_assert …;
static_assert …;
static_assert …;
static_assert …;

#if defined(SK_BUILD_FOR_WIN)
    #include <intrin.h>

    static inline int SkCLZ(uint32_t mask) {
        if (mask) {
            unsigned long index = 0;
            _BitScanReverse(&index, mask);
            // Suppress this bogus /analyze warning. The check for non-zero
            // guarantees that _BitScanReverse will succeed.
            #pragma warning(push)
            #pragma warning(suppress : 6102) // Using 'index' from failed function call
            return static_cast<int>(index ^ 0x1F);
            #pragma warning(pop)
        } else {
            return 32;
        }
    }
#elif defined(SK_CPU_ARM32) || defined(__GNUC__) || defined(__clang__)
    static inline int SkCLZ(uint32_t mask) { … }
#else
    static inline int SkCLZ(uint32_t mask) {
        return SkCLZ_portable(mask);
    }
#endif

//! Returns the number of trailing zero bits (0...32)
// From Hacker's Delight 2nd Edition
constexpr int SkCTZ_portable(uint32_t x) { … }

static_assert …;
static_assert …;
static_assert …;
static_assert …;
static_assert …;

#if defined(SK_BUILD_FOR_WIN)
    #include <intrin.h>

    static inline int SkCTZ(uint32_t mask) {
        if (mask) {
            unsigned long index = 0;
            _BitScanForward(&index, mask);
            // Suppress this bogus /analyze warning. The check for non-zero
            // guarantees that _BitScanReverse will succeed.
            #pragma warning(push)
            #pragma warning(suppress : 6102) // Using 'index' from failed function call
            return static_cast<int>(index);
            #pragma warning(pop)
        } else {
            return 32;
        }
    }
#elif defined(SK_CPU_ARM32) || defined(__GNUC__) || defined(__clang__)
    static inline int SkCTZ(uint32_t mask) { … }
#else
    static inline int SkCTZ(uint32_t mask) {
        return SkCTZ_portable(mask);
    }
#endif

/**
 *  Returns the log2 of the specified value, were that value to be rounded up
 *  to the next power of 2. It is undefined to pass 0. Examples:
 *  SkNextLog2(1) -> 0
 *  SkNextLog2(2) -> 1
 *  SkNextLog2(3) -> 2
 *  SkNextLog2(4) -> 2
 *  SkNextLog2(5) -> 3
 */
static inline int SkNextLog2(uint32_t value) { … }

constexpr int SkNextLog2_portable(uint32_t value) { … }

/**
*  Returns the log2 of the specified value, were that value to be rounded down
*  to the previous power of 2. It is undefined to pass 0. Examples:
*  SkPrevLog2(1) -> 0
*  SkPrevLog2(2) -> 1
*  SkPrevLog2(3) -> 1
*  SkPrevLog2(4) -> 2
*  SkPrevLog2(5) -> 2
*/
static inline int SkPrevLog2(uint32_t value) { … }

constexpr int SkPrevLog2_portable(uint32_t value) { … }

/**
 *  Returns the smallest power-of-2 that is >= the specified value. If value
 *  is already a power of 2, then it is returned unchanged. It is undefined
 *  if value is <= 0.
 */
static inline int SkNextPow2(int value) { … }

constexpr int SkNextPow2_portable(int value) { … }

/**
*  Returns the largest power-of-2 that is <= the specified value. If value
*  is already a power of 2, then it is returned unchanged. It is undefined
*  if value is <= 0.
*/
static inline int SkPrevPow2(int value) { … }

constexpr int SkPrevPow2_portable(int value) { … }

///////////////////////////////////////////////////////////////////////////////

/**
 *  Return the smallest power-of-2 >= n.
 */
static inline uint32_t GrNextPow2(uint32_t n) { … }

/**
 * Returns the next power of 2 >= n or n if the next power of 2 can't be represented by size_t.
 */
static inline size_t GrNextSizePow2(size_t n) { … }

// conservative check. will return false for very large values that "could" fit
template <typename T> static inline bool SkFitsInFixed(T x) { … }

#endif
chromium/third_party/skia/src/base/SkMathPriv.h
