1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/src/core/SkMathPriv.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,71 @@
1.4 +/*
1.5 + * Copyright 2012 Google Inc.
1.6 + *
1.7 + * Use of this source code is governed by a BSD-style license that can be
1.8 + * found in the LICENSE file.
1.9 + */
1.10 +
1.11 +#ifndef SkMathPriv_DEFINED
1.12 +#define SkMathPriv_DEFINED
1.13 +
1.14 +#include "SkMath.h"
1.15 +
1.16 +/** Returns -1 if n < 0, else returns 0
1.17 + */
1.18 +#define SkExtractSign(n) ((int32_t)(n) >> 31)
1.19 +
1.20 +/** If sign == -1, returns -n, else sign must be 0, and returns n.
1.21 + Typically used in conjunction with SkExtractSign().
1.22 + */
1.23 +static inline int32_t SkApplySign(int32_t n, int32_t sign) {
1.24 + SkASSERT(sign == 0 || sign == -1);
1.25 + return (n ^ sign) - sign;
1.26 +}
1.27 +
1.28 +/** Return x with the sign of y */
1.29 +static inline int32_t SkCopySign32(int32_t x, int32_t y) {
1.30 + return SkApplySign(x, SkExtractSign(x ^ y));
1.31 +}
1.32 +
1.33 +/** Given a positive value and a positive max, return the value
1.34 + pinned against max.
1.35 + Note: only works as long as max - value doesn't wrap around
1.36 + @return max if value >= max, else value
1.37 + */
1.38 +static inline unsigned SkClampUMax(unsigned value, unsigned max) {
1.39 + if (value > max) {
1.40 + value = max;
1.41 + }
1.42 + return value;
1.43 +}
1.44 +
1.45 +///////////////////////////////////////////////////////////////////////////////
1.46 +
1.47 +/** Return a*b/255, truncating away any fractional bits. Only valid if both
1.48 + a and b are 0..255
1.49 + */
1.50 +static inline U8CPU SkMulDiv255Trunc(U8CPU a, U8CPU b) {
1.51 + SkASSERT((uint8_t)a == a);
1.52 + SkASSERT((uint8_t)b == b);
1.53 + unsigned prod = SkMulS16(a, b) + 1;
1.54 + return (prod + (prod >> 8)) >> 8;
1.55 +}
1.56 +
1.57 +/** Return (a*b)/255, taking the ceiling of any fractional bits. Only valid if
1.58 + both a and b are 0..255. The expected result equals (a * b + 254) / 255.
1.59 + */
1.60 +static inline U8CPU SkMulDiv255Ceiling(U8CPU a, U8CPU b) {
1.61 + SkASSERT((uint8_t)a == a);
1.62 + SkASSERT((uint8_t)b == b);
1.63 + unsigned prod = SkMulS16(a, b) + 255;
1.64 + return (prod + (prod >> 8)) >> 8;
1.65 +}
1.66 +
1.67 +/** Just the rounding step in SkDiv255Round: round(value / 255)
1.68 + */
1.69 +static inline unsigned SkDiv255Round(unsigned prod) {
1.70 + prod += 128;
1.71 + return (prod + (prod >> 8)) >> 8;
1.72 +}
1.73 +
1.74 +#endif
