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comparison: gfx/skia/trunk/src/core/SkMathPriv.h
gfx/skia/trunk/src/core/SkMathPriv.h
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- TOR_BUG_3246
- changeset 6
- 8bccb770b82d
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| -1:000000000000 | 0:654d0ef8a6c1 |
|---|---|
| 1 /* | |
| 2 * Copyright 2012 Google Inc. | |
| 3 * | |
| 4 * Use of this source code is governed by a BSD-style license that can be | |
| 5 * found in the LICENSE file. | |
| 6 */ | |
| 7 | |
| 8 #ifndef SkMathPriv_DEFINED | |
| 9 #define SkMathPriv_DEFINED | |
| 10 | |
| 11 #include "SkMath.h" | |
| 12 | |
| 13 /** Returns -1 if n < 0, else returns 0 | |
| 14 */ | |
| 15 #define SkExtractSign(n) ((int32_t)(n) >> 31) | |
| 16 | |
| 17 /** If sign == -1, returns -n, else sign must be 0, and returns n. | |
| 18 Typically used in conjunction with SkExtractSign(). | |
| 19 */ | |
| 20 static inline int32_t SkApplySign(int32_t n, int32_t sign) { | |
| 21 SkASSERT(sign == 0 || sign == -1); | |
| 22 return (n ^ sign) - sign; | |
| 23 } | |
| 24 | |
| 25 /** Return x with the sign of y */ | |
| 26 static inline int32_t SkCopySign32(int32_t x, int32_t y) { | |
| 27 return SkApplySign(x, SkExtractSign(x ^ y)); | |
| 28 } | |
| 29 | |
| 30 /** Given a positive value and a positive max, return the value | |
| 31 pinned against max. | |
| 32 Note: only works as long as max - value doesn't wrap around | |
| 33 @return max if value >= max, else value | |
| 34 */ | |
| 35 static inline unsigned SkClampUMax(unsigned value, unsigned max) { | |
| 36 if (value > max) { | |
| 37 value = max; | |
| 38 } | |
| 39 return value; | |
| 40 } | |
| 41 | |
| 42 /////////////////////////////////////////////////////////////////////////////// | |
| 43 | |
| 44 /** Return a*b/255, truncating away any fractional bits. Only valid if both | |
| 45 a and b are 0..255 | |
| 46 */ | |
| 47 static inline U8CPU SkMulDiv255Trunc(U8CPU a, U8CPU b) { | |
| 48 SkASSERT((uint8_t)a == a); | |
| 49 SkASSERT((uint8_t)b == b); | |
| 50 unsigned prod = SkMulS16(a, b) + 1; | |
| 51 return (prod + (prod >> 8)) >> 8; | |
| 52 } | |
| 53 | |
| 54 /** Return (a*b)/255, taking the ceiling of any fractional bits. Only valid if | |
| 55 both a and b are 0..255. The expected result equals (a * b + 254) / 255. | |
| 56 */ | |
| 57 static inline U8CPU SkMulDiv255Ceiling(U8CPU a, U8CPU b) { | |
| 58 SkASSERT((uint8_t)a == a); | |
| 59 SkASSERT((uint8_t)b == b); | |
| 60 unsigned prod = SkMulS16(a, b) + 255; | |
| 61 return (prod + (prod >> 8)) >> 8; | |
| 62 } | |
| 63 | |
| 64 /** Just the rounding step in SkDiv255Round: round(value / 255) | |
| 65 */ | |
| 66 static inline unsigned SkDiv255Round(unsigned prod) { | |
| 67 prod += 128; | |
| 68 return (prod + (prod >> 8)) >> 8; | |
| 69 } | |
| 70 | |
| 71 #endif |
