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      1 /*
      2  * Copyright 2015 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 Sk4px_DEFINED
      9 #define Sk4px_DEFINED
     10 
     11 #include "SkNx.h"
     12 #include "SkColor.h"
     13 #include "SkColorData.h"
     14 
     15 // This file may be included multiple times by .cpp files with different flags, leading
     16 // to different definitions.  Usually that doesn't matter because it's all inlined, but
     17 // in Debug modes the compilers may not inline everything.  So wrap everything in an
     18 // anonymous namespace to give each includer their own silo of this code (or the linker
     19 // will probably pick one randomly for us, which is rarely correct).
     20 namespace {
     21 
     22 // 1, 2 or 4 SkPMColors, generally vectorized.
     23 class Sk4px : public Sk16b {
     24 public:
     25     static Sk4px DupAlpha(SkAlpha a) { return Sk16b(a); }  //    a -> aaaa aaaa aaaa aaaa
     26     static Sk4px DupPMColor(SkPMColor c);                  // argb -> argb argb argb argb
     27 
     28     Sk4px(const Sk16b& v) : INHERITED(v) {}
     29 
     30     Sk4px alphas() const;  // ARGB argb XYZW xyzw -> AAAA aaaa XXXX xxxx
     31 
     32     // Mask away color or alpha lanes.
     33     Sk4px zeroColors() const;  // ARGB argb XYZW xyzw -> A000 a000 X000 x000
     34     Sk4px zeroAlphas() const;  // ARGB argb XYZW xyzw -> 0RGB 0rgb 0YZW 0yzw
     35 
     36     Sk4px inv() const { return Sk16b(255) - *this; }
     37 
     38     // When loading or storing fewer than 4 SkPMColors, we use the low lanes.
     39     static Sk4px Load4(const SkPMColor[4]);  // PMColor[4] -> ARGB argb XYZW xyzw
     40     static Sk4px Load2(const SkPMColor[2]);  // PMColor[2] -> ARGB argb ???? ????
     41     static Sk4px Load1(const SkPMColor[1]);  // PMColor[1] -> ARGB ???? ???? ????
     42 
     43     // Ditto for Alphas... Load2Alphas fills the low two lanes of Sk4px.
     44     static Sk4px Load4Alphas(const SkAlpha[4]);  // AaXx -> AAAA aaaa XXXX xxxx
     45     static Sk4px Load2Alphas(const SkAlpha[2]);  // Aa   -> AAAA aaaa ???? ????
     46 
     47     void store4(SkPMColor[4]) const;
     48     void store2(SkPMColor[2]) const;
     49     void store1(SkPMColor[1]) const;
     50 
     51     // 1, 2, or 4 SkPMColors with 16-bit components.
     52     // This is most useful as the result of a multiply, e.g. from mulWiden().
     53     class Wide : public Sk16h {
     54     public:
     55         Wide(const Sk16h& v) : Sk16h(v) {}
     56 
     57         // Pack the top byte of each component back down into 4 SkPMColors.
     58         Sk4px addNarrowHi(const Sk16h&) const;
     59 
     60         // Rounds, i.e. (x+127) / 255.
     61         Sk4px div255() const;
     62 
     63         // These just keep the types as Wide so the user doesn't have to keep casting.
     64         Wide operator * (const Wide& o) const { return INHERITED::operator*(o); }
     65         Wide operator + (const Wide& o) const { return INHERITED::operator+(o); }
     66         Wide operator - (const Wide& o) const { return INHERITED::operator-(o); }
     67         Wide operator >> (int bits) const { return INHERITED::operator>>(bits); }
     68         Wide operator << (int bits) const { return INHERITED::operator<<(bits); }
     69         static Wide Min(const Wide& a, const Wide& b) { return INHERITED::Min(a,b); }
     70         Wide thenElse(const Wide& t, const Wide& e) const { return INHERITED::thenElse(t,e); }
     71 
     72     private:
     73         typedef Sk16h INHERITED;
     74     };
     75 
     76     Wide widenLo() const;               // ARGB -> 0A 0R 0G 0B
     77     Wide widenHi() const;               // ARGB -> A0 R0 G0 B0
     78     Wide widenLoHi() const;             // ARGB -> AA RR GG BB
     79     Wide mulWiden(const Sk16b&) const;  // 8-bit x 8-bit -> 16-bit components.
     80 
     81     // The only 8-bit multiply we use is 8-bit x 8-bit -> 16-bit.  Might as well make it pithy.
     82     Wide operator * (const Sk4px& o) const { return this->mulWiden(o); }
     83 
     84     // These just keep the types as Sk4px so the user doesn't have to keep casting.
     85     Sk4px operator + (const Sk4px& o) const { return INHERITED::operator+(o); }
     86     Sk4px operator - (const Sk4px& o) const { return INHERITED::operator-(o); }
     87     Sk4px operator < (const Sk4px& o) const { return INHERITED::operator<(o); }
     88     Sk4px thenElse(const Sk4px& t, const Sk4px& e) const { return INHERITED::thenElse(t,e); }
     89 
     90     // Generally faster than (*this * o).div255().
     91     // May be incorrect by +-1, but is always exactly correct when *this or o is 0 or 255.
     92     Sk4px approxMulDiv255(const Sk16b& o) const {
     93         // (x*y + x) / 256 meets these criteria.  (As of course does (x*y + y) / 256 by symmetry.)
     94         // FYI: (x*y + 255) / 256 also meets these criteria.  In my brief testing, it was slower.
     95         return this->widenLo().addNarrowHi(*this * o);
     96     }
     97 
     98     // A generic driver that maps fn over a src array into a dst array.
     99     // fn should take an Sk4px (4 src pixels) and return an Sk4px (4 dst pixels).
    100     template <typename Fn>
    101     static void MapSrc(int n, SkPMColor* dst, const SkPMColor* src, const Fn& fn) {
    102         SkASSERT(dst);
    103         SkASSERT(src);
    104         // This looks a bit odd, but it helps loop-invariant hoisting across different calls to fn.
    105         // Basically, we need to make sure we keep things inside a single loop.
    106         while (n > 0) {
    107             if (n >= 8) {
    108                 Sk4px dst0 = fn(Load4(src+0)),
    109                       dst4 = fn(Load4(src+4));
    110                 dst0.store4(dst+0);
    111                 dst4.store4(dst+4);
    112                 dst += 8; src += 8; n -= 8;
    113                 continue;  // Keep our stride at 8 pixels as long as possible.
    114             }
    115             SkASSERT(n <= 7);
    116             if (n >= 4) {
    117                 fn(Load4(src)).store4(dst);
    118                 dst += 4; src += 4; n -= 4;
    119             }
    120             if (n >= 2) {
    121                 fn(Load2(src)).store2(dst);
    122                 dst += 2; src += 2; n -= 2;
    123             }
    124             if (n >= 1) {
    125                 fn(Load1(src)).store1(dst);
    126             }
    127             break;
    128         }
    129     }
    130 
    131     // As above, but with dst4' = fn(dst4, src4).
    132     template <typename Fn>
    133     static void MapDstSrc(int n, SkPMColor* dst, const SkPMColor* src, const Fn& fn) {
    134         SkASSERT(dst);
    135         SkASSERT(src);
    136         while (n > 0) {
    137             if (n >= 8) {
    138                 Sk4px dst0 = fn(Load4(dst+0), Load4(src+0)),
    139                       dst4 = fn(Load4(dst+4), Load4(src+4));
    140                 dst0.store4(dst+0);
    141                 dst4.store4(dst+4);
    142                 dst += 8; src += 8; n -= 8;
    143                 continue;  // Keep our stride at 8 pixels as long as possible.
    144             }
    145             SkASSERT(n <= 7);
    146             if (n >= 4) {
    147                 fn(Load4(dst), Load4(src)).store4(dst);
    148                 dst += 4; src += 4; n -= 4;
    149             }
    150             if (n >= 2) {
    151                 fn(Load2(dst), Load2(src)).store2(dst);
    152                 dst += 2; src += 2; n -= 2;
    153             }
    154             if (n >= 1) {
    155                 fn(Load1(dst), Load1(src)).store1(dst);
    156             }
    157             break;
    158         }
    159     }
    160 
    161     // As above, but with dst4' = fn(dst4, alpha4).
    162     template <typename Fn>
    163     static void MapDstAlpha(int n, SkPMColor* dst, const SkAlpha* a, const Fn& fn) {
    164         SkASSERT(dst);
    165         SkASSERT(a);
    166         while (n > 0) {
    167             if (n >= 8) {
    168                 Sk4px dst0 = fn(Load4(dst+0), Load4Alphas(a+0)),
    169                       dst4 = fn(Load4(dst+4), Load4Alphas(a+4));
    170                 dst0.store4(dst+0);
    171                 dst4.store4(dst+4);
    172                 dst += 8; a += 8; n -= 8;
    173                 continue;  // Keep our stride at 8 pixels as long as possible.
    174             }
    175             SkASSERT(n <= 7);
    176             if (n >= 4) {
    177                 fn(Load4(dst), Load4Alphas(a)).store4(dst);
    178                 dst += 4; a += 4; n -= 4;
    179             }
    180             if (n >= 2) {
    181                 fn(Load2(dst), Load2Alphas(a)).store2(dst);
    182                 dst += 2; a += 2; n -= 2;
    183             }
    184             if (n >= 1) {
    185                 fn(Load1(dst), DupAlpha(*a)).store1(dst);
    186             }
    187             break;
    188         }
    189     }
    190 
    191     // As above, but with dst4' = fn(dst4, src4, alpha4).
    192     template <typename Fn>
    193     static void MapDstSrcAlpha(int n, SkPMColor* dst, const SkPMColor* src, const SkAlpha* a,
    194                                const Fn& fn) {
    195         SkASSERT(dst);
    196         SkASSERT(src);
    197         SkASSERT(a);
    198         while (n > 0) {
    199             if (n >= 8) {
    200                 Sk4px dst0 = fn(Load4(dst+0), Load4(src+0), Load4Alphas(a+0)),
    201                       dst4 = fn(Load4(dst+4), Load4(src+4), Load4Alphas(a+4));
    202                 dst0.store4(dst+0);
    203                 dst4.store4(dst+4);
    204                 dst += 8; src += 8; a += 8; n -= 8;
    205                 continue;  // Keep our stride at 8 pixels as long as possible.
    206             }
    207             SkASSERT(n <= 7);
    208             if (n >= 4) {
    209                 fn(Load4(dst), Load4(src), Load4Alphas(a)).store4(dst);
    210                 dst += 4; src += 4; a += 4; n -= 4;
    211             }
    212             if (n >= 2) {
    213                 fn(Load2(dst), Load2(src), Load2Alphas(a)).store2(dst);
    214                 dst += 2; src += 2; a += 2; n -= 2;
    215             }
    216             if (n >= 1) {
    217                 fn(Load1(dst), Load1(src), DupAlpha(*a)).store1(dst);
    218             }
    219             break;
    220         }
    221     }
    222 
    223 private:
    224     typedef Sk16b INHERITED;
    225 };
    226 
    227 }  // namespace
    228 
    229 #ifdef SKNX_NO_SIMD
    230     #include "../opts/Sk4px_none.h"
    231 #else
    232     #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
    233         #include "../opts/Sk4px_SSE2.h"
    234     #elif defined(SK_ARM_HAS_NEON)
    235         #include "../opts/Sk4px_NEON.h"
    236     #else
    237         #include "../opts/Sk4px_none.h"
    238     #endif
    239 #endif
    240 
    241 #endif//Sk4px_DEFINED
    242