gfx/skia/trunk/src/core/SkMathPriv.h@6474c204b198 (annotated)
gfx/skia/trunk/src/core/SkMathPriv.h
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
| michael@0 | 1 | /* |
| michael@0 | 2 | * Copyright 2012 Google Inc. |
| michael@0 | 3 | * |
| michael@0 | 4 | * Use of this source code is governed by a BSD-style license that can be |
| michael@0 | 5 | * found in the LICENSE file. |
| michael@0 | 6 | */ |
| michael@0 | 7 | |
| michael@0 | 8 | #ifndef SkMathPriv_DEFINED |
| michael@0 | 9 | #define SkMathPriv_DEFINED |
| michael@0 | 10 | |
| michael@0 | 11 | #include "SkMath.h" |
| michael@0 | 12 | |
| michael@0 | 13 | /** Returns -1 if n < 0, else returns 0 |
| michael@0 | 14 | */ |
| michael@0 | 15 | #define SkExtractSign(n) ((int32_t)(n) >> 31) |
| michael@0 | 16 | |
| michael@0 | 17 | /** If sign == -1, returns -n, else sign must be 0, and returns n. |
| michael@0 | 18 | Typically used in conjunction with SkExtractSign(). |
| michael@0 | 19 | */ |
| michael@0 | 20 | static inline int32_t SkApplySign(int32_t n, int32_t sign) { |
| michael@0 | 21 | SkASSERT(sign == 0 || sign == -1); |
| michael@0 | 22 | return (n ^ sign) - sign; |
| michael@0 | 23 | } |
| michael@0 | 24 | |
| michael@0 | 25 | /** Return x with the sign of y */ |
| michael@0 | 26 | static inline int32_t SkCopySign32(int32_t x, int32_t y) { |
| michael@0 | 27 | return SkApplySign(x, SkExtractSign(x ^ y)); |
| michael@0 | 28 | } |
| michael@0 | 29 | |
| michael@0 | 30 | /** Given a positive value and a positive max, return the value |
| michael@0 | 31 | pinned against max. |
| michael@0 | 32 | Note: only works as long as max - value doesn't wrap around |
| michael@0 | 33 | @return max if value >= max, else value |
| michael@0 | 34 | */ |
| michael@0 | 35 | static inline unsigned SkClampUMax(unsigned value, unsigned max) { |
| michael@0 | 36 | if (value > max) { |
| michael@0 | 37 | value = max; |
| michael@0 | 38 | } |
| michael@0 | 39 | return value; |
| michael@0 | 40 | } |
| michael@0 | 41 | |
| michael@0 | 42 | /////////////////////////////////////////////////////////////////////////////// |
| michael@0 | 43 | |
| michael@0 | 44 | /** Return a*b/255, truncating away any fractional bits. Only valid if both |
| michael@0 | 45 | a and b are 0..255 |
| michael@0 | 46 | */ |
| michael@0 | 47 | static inline U8CPU SkMulDiv255Trunc(U8CPU a, U8CPU b) { |
| michael@0 | 48 | SkASSERT((uint8_t)a == a); |
| michael@0 | 49 | SkASSERT((uint8_t)b == b); |
| michael@0 | 50 | unsigned prod = SkMulS16(a, b) + 1; |
| michael@0 | 51 | return (prod + (prod >> 8)) >> 8; |
| michael@0 | 52 | } |
| michael@0 | 53 | |
| michael@0 | 54 | /** Return (a*b)/255, taking the ceiling of any fractional bits. Only valid if |
| michael@0 | 55 | both a and b are 0..255. The expected result equals (a * b + 254) / 255. |
| michael@0 | 56 | */ |
| michael@0 | 57 | static inline U8CPU SkMulDiv255Ceiling(U8CPU a, U8CPU b) { |
| michael@0 | 58 | SkASSERT((uint8_t)a == a); |
| michael@0 | 59 | SkASSERT((uint8_t)b == b); |
| michael@0 | 60 | unsigned prod = SkMulS16(a, b) + 255; |
| michael@0 | 61 | return (prod + (prod >> 8)) >> 8; |
| michael@0 | 62 | } |
| michael@0 | 63 | |
| michael@0 | 64 | /** Just the rounding step in SkDiv255Round: round(value / 255) |
| michael@0 | 65 | */ |
| michael@0 | 66 | static inline unsigned SkDiv255Round(unsigned prod) { |
| michael@0 | 67 | prod += 128; |
| michael@0 | 68 | return (prod + (prod >> 8)) >> 8; |
| michael@0 | 69 | } |
| michael@0 | 70 | |
| michael@0 | 71 | #endif |
