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- /*
- * 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/core/SkMath.h"
- /**
- * 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) { return SkSqrtBits(n, 15); }
- /**
- * Returns (value < 0 ? 0 : value) efficiently (i.e. no compares or branches)
- */
- static inline int SkClampPos(int value) {
- return value & ~(value >> 31);
- }
- /**
- * 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) {
- #ifdef SK_CPU_ARM32
- // If we wrote this as in the else branch, GCC won't fuse the two into one
- // divmod call, but rather a div call followed by a divmod. Silly! This
- // version is just as fast as calling __aeabi_[u]idivmod manually, but with
- // prettier code.
- //
- // This benches as around 2x faster than the code in the else branch.
- const In d = numer/denom;
- *div = static_cast<Out>(d);
- *mod = static_cast<Out>(numer-d*denom);
- #else
- // On x86 this will just be a single idiv.
- *div = static_cast<Out>(numer/denom);
- *mod = static_cast<Out>(numer%denom);
- #endif
- }
- /** Returns -1 if n < 0, else returns 0
- */
- #define SkExtractSign(n) ((int32_t)(n) >> 31)
- /** 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) {
- SkASSERT(sign == 0 || sign == -1);
- return (n ^ sign) - sign;
- }
- /** Return x with the sign of y */
- static inline int32_t SkCopySign32(int32_t x, int32_t y) {
- return SkApplySign(x, SkExtractSign(x ^ 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 (value > max) {
- value = max;
- }
- return value;
- }
- // 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) {
- #if defined(_MSC_VER)
- #pragma warning(push)
- #pragma warning(disable : 4146) // Thanks MSVC, we know what we're negating an unsigned
- #endif
- return -static_cast<size_t>(value);
- #if defined(_MSC_VER)
- #pragma warning(pop)
- #endif
- }
- ///////////////////////////////////////////////////////////////////////////////
- /** 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) {
- SkASSERT((uint8_t)a == a);
- SkASSERT((uint8_t)b == b);
- unsigned prod = a*b + 1;
- return (prod + (prod >> 8)) >> 8;
- }
- /** 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) {
- SkASSERT((uint8_t)a == a);
- SkASSERT((uint8_t)b == b);
- unsigned prod = a*b + 255;
- return (prod + (prod >> 8)) >> 8;
- }
- /** Just the rounding step in SkDiv255Round: round(value / 255)
- */
- static inline unsigned SkDiv255Round(unsigned prod) {
- prod += 128;
- return (prod + (prod >> 8)) >> 8;
- }
- static inline float SkPinToUnitFloat(float x) {
- return SkTMin(SkTMax(x, 0.0f), 1.0f);
- }
- /**
- * 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) { return __builtin_bswap32(v); }
- #endif
- //! Returns the number of leading zero bits (0...32)
- int SkCLZ_portable(uint32_t);
- #ifndef SkCLZ
- #if defined(SK_BUILD_FOR_WIN)
- #include <intrin.h>
- static inline int SkCLZ(uint32_t mask) {
- if (mask) {
- unsigned long index;
- _BitScanReverse(&index, mask);
- // Suppress this bogus /analyze warning. The check for non-zero
- // guarantees that _BitScanReverse will succeed.
- #pragma warning(suppress : 6102) // Using 'index' from failed function call
- return index ^ 0x1F;
- } else {
- return 32;
- }
- }
- #elif defined(SK_CPU_ARM32) || defined(__GNUC__) || defined(__clang__)
- static inline int SkCLZ(uint32_t mask) {
- // __builtin_clz(0) is undefined, so we have to detect that case.
- return mask ? __builtin_clz(mask) : 32;
- }
- #else
- #define SkCLZ(x) SkCLZ_portable(x)
- #endif
- #endif
- /**
- * 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) {
- SkASSERT(value > 0);
- return 1 << (32 - SkCLZ(value - 1));
- }
- /**
- * 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) {
- SkASSERT(value > 0);
- return 1 << (32 - SkCLZ(value >> 1));
- }
- /**
- * 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) {
- SkASSERT(value != 0);
- return 32 - SkCLZ(value - 1);
- }
- /**
- * 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) {
- SkASSERT(value != 0);
- return 32 - SkCLZ(value >> 1);
- }
- ///////////////////////////////////////////////////////////////////////////////
- /**
- * Return the smallest power-of-2 >= n.
- */
- static inline uint32_t GrNextPow2(uint32_t n) {
- return n ? (1 << (32 - SkCLZ(n - 1))) : 1;
- }
- /**
- * 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) {
- constexpr int kNumSizeTBits = 8 * sizeof(size_t);
- constexpr size_t kHighBitSet = size_t(1) << (kNumSizeTBits - 1);
- if (!n) {
- return 1;
- } else if (n >= kHighBitSet) {
- return n;
- }
- n--;
- uint32_t shift = 1;
- while (shift < kNumSizeTBits) {
- n |= n >> shift;
- shift <<= 1;
- }
- return n + 1;
- }
- // conservative check. will return false for very large values that "could" fit
- template <typename T> static inline bool SkFitsInFixed(T x) {
- return SkTAbs(x) <= 32767.0f;
- }
- #endif
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