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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 "SkMath.h" /** 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; } /** Computes the 64bit product of a * b, and then shifts the answer down by shift bits, returning the low 32bits. shift must be [0..63] e.g. to perform a fixedmul, call SkMulShift(a, b, 16) */ int32_t SkMulShift(int32_t a, int32_t b, unsigned shift); /** Return the integer cube root of value, with a bias of bitBias */ int32_t SkCubeRootBits(int32_t value, int bitBias); /////////////////////////////////////////////////////////////////////////////// /** 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 = SkMulS16(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 = SkMulS16(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; } #endif