Revert of Add specialized sRGB blitter for SkOpts

src/opts/SkBlend_opts.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
-/*
-ninja -C out/Release dm nanobench ; and ./out/Release/dm --match Blend_opts ; and ./out/Release/nanobench  --samples 300 --nompd --match LinearSrcOver -q
- */
-
 #ifndef SkBlend_opts_DEFINED
 #define SkBlend_opts_DEFINED
 
-#include "SkNx.h"
-#include "SkPM4fPriv.h"
-
 namespace SK_OPTS_NS {
 
-// An implementation of SrcOver from bytes to bytes in linear space that takes advantage of the
-// observation that the 255's cancel.
-//    invA = 1 - (As / 255);
-//
-//    R = 255 * sqrt((Rs/255)^2 + (Rd/255)^2 * invA)
-// => R = 255 * sqrt((Rs^2 + Rd^2 * invA)/255^2)
-// => R = sqrt(Rs^2 + Rd^2 * invA)
-static inline void blend_srgb_srgb_1(uint32_t* dst, const uint32_t pixel) {
-    Sk4f s = srgb_to_linear(to_4f(pixel));
-    Sk4f d = srgb_to_linear(to_4f(*dst));
-    Sk4f invAlpha = 1.0f - Sk4f{s[SkPM4f::A]} * (1.0f / 255.0f);
-    Sk4f r = linear_to_srgb(s + d * invAlpha) + 0.5f;
-    *dst = to_4b(r);
-}
+#if 0
 
-static inline void srcover_srgb_srgb_1(uint32_t* dst, const uint32_t pixel) {
-    if ((~pixel & 0xFF000000) == 0) {
-        *dst = pixel;
-    } else if ((pixel & 0xFF000000) != 0) {
-        blend_srgb_srgb_1(dst, pixel);
+#else
+
+    static inline void srcover_srgb_srgb_1(uint32_t* dst, uint32_t src) {
+        switch (src >> 24) {
+            case 0x00:             return; 
+            case 0xff: *dst = src; return;
+        }
+
+        Sk4f d = SkNx_cast<float>(Sk4b::Load( dst)),
+             s = SkNx_cast<float>(Sk4b::Load(&src));
+
+        // Approximate sRGB gamma as 2.0.
+        Sk4f d_sq = d*d,
+             s_sq = s*s;
+        d = Sk4f{d_sq[0], d_sq[1], d_sq[2], d[3]};
+        s = Sk4f{s_sq[0], s_sq[1], s_sq[2], s[3]};
+
+        // SrcOver.
+        Sk4f invA = 1.0f - s[3]*(1/255.0f);
+        d = s + d * invA;
+
+        // Re-apply approximate sRGB gamma.
+        Sk4f d_sqrt = d.sqrt();
+        d = Sk4f{d_sqrt[0], d_sqrt[1], d_sqrt[2], d[3]};
+
+        SkNx_cast<uint8_t>(d).store(dst);
     }
-}
 
-static inline void srcover_srgb_srgb_2(uint32_t* dst, const uint32_t* src) {
-    srcover_srgb_srgb_1(dst++, *src++);
-    srcover_srgb_srgb_1(dst, *src);
-}
+    static inline void srcover_srgb_srgb(uint32_t* dst, const uint32_t* const src, int ndst, const int nsrc) {
+        while (ndst > 0) {
+            int n = SkTMin(ndst, nsrc);
 
-static inline void srcover_srgb_srgb_4(uint32_t* dst, const uint32_t* src) {
-    srcover_srgb_srgb_1(dst++, *src++);
-    srcover_srgb_srgb_1(dst++, *src++);
-    srcover_srgb_srgb_1(dst++, *src++);
-    srcover_srgb_srgb_1(dst, *src);
-}
-
-void best_non_simd_srcover_srgb_srgb(
-    uint32_t* dst, const uint32_t* const src, int ndst, const int nsrc) {
-    uint64_t* ddst = reinterpret_cast<uint64_t*>(dst);
-
-    while (ndst >0) {
-        int count = SkTMin(ndst, nsrc);
-        ndst -= count;
-        const uint64_t* dsrc = reinterpret_cast<const uint64_t*>(src);
-        const uint64_t* end = dsrc + (count >> 1);
-        do {
-            if ((~*dsrc & 0xFF000000FF000000) == 0) {
-                do {
-                    *ddst++ = *dsrc++;
-                } while (dsrc < end && (~*dsrc & 0xFF000000FF000000) == 0);
-            } else if ((*dsrc & 0xFF000000FF000000) == 0) {
-                do {
-                    dsrc++;
-                    ddst++;
-                } while (dsrc < end && (*dsrc & 0xFF000000FF000000) == 0);
-            } else {
-                srcover_srgb_srgb_2(reinterpret_cast<uint32_t*>(ddst++),
-                                    reinterpret_cast<const uint32_t*>(dsrc++));
+            for (int i = 0; i < n; i++) {
+                srcover_srgb_srgb_1(dst++, src[i]);
             }
-        } while (dsrc < end);
-
-        if ((count & 1) != 0) {
-            srcover_srgb_srgb_1(reinterpret_cast<uint32_t*>(ddst),
-                                *reinterpret_cast<const uint32_t*>(dsrc));
+            ndst -= n;
         }
     }
-}
-
-void brute_force_srcover_srgb_srgb(
-    uint32_t* dst, const uint32_t* const src, int ndst, const int nsrc) {
-    while (ndst > 0) {
-        int n = SkTMin(ndst, nsrc);
-
-        for (int i = 0; i < n; i++) {
-            blend_srgb_srgb_1(dst++, src[i]);
-        }
-        ndst -= n;
-    }
-}
-
-void trivial_srcover_srgb_srgb(
-    uint32_t* dst, const uint32_t* const src, int ndst, const int nsrc) {
-    while (ndst > 0) {
-        int n = SkTMin(ndst, nsrc);
-
-        for (int i = 0; i < n; i++) {
-            srcover_srgb_srgb_1(dst++, src[i]);
-        }
-        ndst -= n;
-    }
-}
-
-#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
-
-    static inline __m128i load(const uint32_t* p) {
-        return _mm_loadu_si128(reinterpret_cast<const __m128i*>(p));
-    }
-
-    static inline void store(uint32_t* p, __m128i v) {
-        _mm_storeu_si128(reinterpret_cast<__m128i*>(p), v);
-    }
-
-    #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE41
-
-        void srcover_srgb_srgb(
-            uint32_t* dst, const uint32_t* const srcStart, int ndst, const int nsrc) {
-            const __m128i alphaMask = _mm_set1_epi32(0xFF000000);
-            while (ndst > 0) {
-                int count = SkTMin(ndst, nsrc);
-                ndst -= count;
-                const uint32_t* src = srcStart;
-                const uint32_t* end = src + (count & ~3);
-
-                while (src < end) {
-                    __m128i pixels = load(src);
-                    if (_mm_testc_si128(pixels, alphaMask)) {
-                        do {
-                            store(dst, pixels);
-                            dst += 4;
-                            src += 4;
-                        } while (src < end && _mm_testc_si128(pixels = load(src), alphaMask));
-                    } else if (_mm_testz_si128(pixels, alphaMask)) {
-                        do {
-                            dst += 4;
-                            src += 4;
-                        } while (src < end && _mm_testz_si128(pixels = load(src), alphaMask));
-                    } else {
-                        do {
-                            srcover_srgb_srgb_4(dst, src);
-                            dst += 4;
-                            src += 4;
-                        } while (src < end && _mm_testnzc_si128(pixels = load(src), alphaMask));
-                    }
-                }
-
-                count = count & 3;
-                while (count-- > 0) {
-                    srcover_srgb_srgb_1(dst++, *src++);
-                }
-            }
-        }
-    #else
-    // SSE2 versions
-        static inline bool check_opaque_alphas(__m128i pixels) {
-            int mask =
-                _mm_movemask_epi8(
-                    _mm_cmpeq_epi32(
-                        _mm_andnot_si128(pixels, _mm_set1_epi32(0xFF000000)),
-                        _mm_setzero_si128()));
-            return mask == 0xFFFF;
-        }
-
-        static inline bool check_transparent_alphas(__m128i pixels) {
-            int mask =
-                _mm_movemask_epi8(
-                    _mm_cmpeq_epi32(
-                        _mm_and_si128(pixels, _mm_set1_epi32(0xFF000000)),
-                        _mm_setzero_si128()));
-            return mask == 0xFFFF;
-        }
-
-        static inline bool check_partial_alphas(__m128i pixels) {
-            __m128i alphas = _mm_and_si128(pixels, _mm_set1_epi32(0xFF000000));
-            int mask =
-                _mm_movemask_epi8(
-                    _mm_cmpeq_epi8(
-                        _mm_srai_epi32(alphas, 8),
-                        alphas));
-            return mask == 0xFFFF;
-        }
-
-        void srcover_srgb_srgb(
-            uint32_t* dst, const uint32_t* const srcStart, int ndst, const int nsrc) {
-            while (ndst > 0) {
-                int count = SkTMin(ndst, nsrc);
-                ndst -= count;
-                const uint32_t* src = srcStart;
-                const uint32_t* end = src + (count & ~3);
-
-                __m128i pixels = load(src);
-                do {
-                    if (check_opaque_alphas(pixels)) {
-                        do {
-                            store(dst, pixels);
-                            dst += 4;
-                            src += 4;
-                        } while (src < end && check_opaque_alphas(pixels = load(src)));
-                    } else if (check_transparent_alphas(pixels)) {
-                        const uint32_t* start = src;
-                        do {
-                            src += 4;
-                        } while (src < end && check_transparent_alphas(pixels = load(src)));
-                        dst += src - start;
-                    } else {
-                        do {
-                            srcover_srgb_srgb_4(dst, src);
-                            dst += 4;
-                            src += 4;
-                        } while (src < end && check_partial_alphas(pixels = load(src)));
-                    }
-                } while (src < end);
-
-                count = count & 3;
-                while (count-- > 0) {
-                    srcover_srgb_srgb_1(dst++, *src++);
-                }
-            }
-        }
-    #endif
-#else
-
-    void srcover_srgb_srgb(
-        uint32_t* dst, const uint32_t* const src, int ndst, const int nsrc) {
-        trivial_srcover_srgb_srgb(dst, src, ndst, nsrc);
-    }
-
+    
 #endif
 
 }  // namespace SK_OPTS_NS
 
 #endif//SkBlend_opts_DEFINED