generalize xferu64 procs using proc4f

src/core/SkXfermodeU64.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkHalf.h"
 #include "SkPM4fPriv.h"
 #include "SkUtils.h"
@@ skipping 12 matching lines @@
 
 enum DstType {
     kU16_Dst,
     kF16_Dst,
 };
 
 static Sk4f lerp_by_coverage(const Sk4f& src, const Sk4f& dst, uint8_t srcCoverage) {
     return dst + (src - dst) * Sk4f(srcCoverage * (1/255.0f));
 }
 
-template <DstType D> Sk4f unit_to_dst_bias(const Sk4f& x4) {
+template <DstType D> Sk4f unit_to_bias(const Sk4f& x4) {
     return (D == kU16_Dst) ? x4 * Sk4f(65535) : x4;
 }
 
+template <DstType D> Sk4f bias_to_unit(const Sk4f& x4) {
+    return (D == kU16_Dst) ? x4 * Sk4f(1.0f/65535) : x4;
+}
+
 // returns value already biased by 65535
 static Sk4f load_from_u16(uint64_t value) {
     return SkNx_cast<float>(Sk4h::Load(&value));
 }
 
 // takes floats already biased by 65535
 static uint64_t store_to_u16(const Sk4f& x4) {
     uint64_t value;
     SkNx_cast<uint16_t>(x4 + Sk4f(0.5f)).store(&value);
     return value;
@@ skipping 26 matching lines @@
     return (D == kU16_Dst) ? load_from_u16(dst) : load_from_f16(dst);
 }
 
 // Assumes x4 is already in the "natural" bias (either unit-float or 16bit int)
 template <DstType D> uint64_t store_to_dst(const Sk4f& x4) {
     return (D == kU16_Dst) ? store_to_u16(x4) : store_to_f16(x4);
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
+template <DstType D> void src_u64_1(const SkXfermode::U64State& state, uint64_t dst[],

[mtklein, 2016/02/10 16:19:34]

why is this called src_u64_1?  It's not always src mode, is it?

+                                    const SkPM4f& src, int count, const SkAlpha aa[]) {
+    SkXfermodeProc4f proc = state.fXfer->getProc4f();
+    SkPM4f d;
+    if (aa) {
+        for (int i = 0; i < count; ++i) {
+            Sk4f d4 = bias_to_unit<D>(load_from_dst<D>(dst[i]));
+            d4.store(d.fVec);

[mtklein, 2016/02/10 16:19:34]

Do these stores and loads disappear?  Seems like they can't?

We might try next making SkPM4f be or have an Sk4f.

+            Sk4f r4 = unit_to_bias<D>(Sk4f::Load(proc(src, d).fVec));
+            dst[i] = store_to_dst<D>(lerp_by_coverage(r4, d4, aa[i]));
+        }
+    } else {
+        for (int i = 0; i < count; ++i) {
+            bias_to_unit<D>(load_from_dst<D>(dst[i])).store(d.fVec);
+            Sk4f r4 = unit_to_bias<D>(Sk4f::Load(proc(src, d).fVec));
+            dst[i] = store_to_dst<D>(r4);
+        }
+    }
+}
+
+template <DstType D> void xfer_u64_n(const SkXfermode::U64State& state, uint64_t dst[],
+                                     const SkPM4f src[], int count, const SkAlpha aa[]) {
+    SkXfermodeProc4f proc = state.fXfer->getProc4f();
+    SkPM4f d;
+    if (aa) {
+        for (int i = 0; i < count; ++i) {
+            Sk4f d4 = bias_to_unit<D>(load_from_dst<D>(dst[i]));
+            d4.store(d.fVec);
+            Sk4f r4 = unit_to_bias<D>(Sk4f::Load(proc(src[i], d).fVec));
+            dst[i] = store_to_dst<D>(lerp_by_coverage(r4, d4, aa[i]));
+        }
+    } else {
+        for (int i = 0; i < count; ++i) {
+            bias_to_unit<D>(load_from_dst<D>(dst[i])).store(d.fVec);
+            Sk4f r4 = unit_to_bias<D>(Sk4f::Load(proc(src[i], d).fVec));
+            dst[i] = store_to_dst<D>(r4);
+        }
+    }
+}
+
+const U64ProcPair gU64Procs_General[] = {
+    { src_u64_1<kU16_Dst>, xfer_u64_n<kU16_Dst> },   // U16     alpha
+    { src_u64_1<kU16_Dst>, xfer_u64_n<kU16_Dst> },   // U16     opaque
+    { src_u64_1<kF16_Dst>, xfer_u64_n<kF16_Dst> },   // F16     alpha
+    { src_u64_1<kF16_Dst>, xfer_u64_n<kF16_Dst> },   // F16     opaque
+};
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
 template <DstType D> void src_1(const SkXfermode::U64State& state, uint64_t dst[],
                                 const SkPM4f& src, int count, const SkAlpha aa[]) {
-    const Sk4f s4 = unit_to_dst_bias<D>(Sk4f::Load(src.fVec));
+    const Sk4f s4 = unit_to_bias<D>(Sk4f::Load(src.fVec));
     if (aa) {
         for (int i = 0; i < count; ++i) {
             const Sk4f d4 = load_from_dst<D>(dst[i]);
             dst[i] = store_to_dst<D>(lerp_by_coverage(s4, d4, aa[i]));
         }
     } else {
         sk_memset64(dst, store_to_dst<D>(s4), count);
     }
 }
 
 template <DstType D> void src_n(const SkXfermode::U64State& state, uint64_t dst[],
                                 const SkPM4f src[], int count, const SkAlpha aa[]) {
     if (aa) {
         for (int i = 0; i < count; ++i) {
-            const Sk4f s4 = unit_to_dst_bias<D>(Sk4f::Load(src[i].fVec));
+            const Sk4f s4 = unit_to_bias<D>(Sk4f::Load(src[i].fVec));
             const Sk4f d4 = load_from_dst<D>(dst[i]);
             dst[i] = store_to_dst<D>(lerp_by_coverage(s4, d4, aa[i]));
         }
     } else {
         for (int i = 0; i < count; ++i) {
-            const Sk4f s4 = unit_to_dst_bias<D>(Sk4f::Load(src[i].fVec));
+            const Sk4f s4 = unit_to_bias<D>(Sk4f::Load(src[i].fVec));
             dst[i] = store_to_dst<D>(s4);
         }
     }
 }
 
 const U64ProcPair gU64Procs_Src[] = {
     { src_1<kU16_Dst>, src_n<kU16_Dst>  },   // U16     alpha
     { src_1<kU16_Dst>, src_n<kU16_Dst>  },   // U16     opaque
     { src_1<kF16_Dst>, src_n<kF16_Dst>  },   // F16     alpha
     { src_1<kF16_Dst>, src_n<kF16_Dst>  },   // F16     opaque
 };
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 template <DstType D> void srcover_1(const SkXfermode::U64State& state, uint64_t dst[],
                                     const SkPM4f& src, int count, const SkAlpha aa[]) {
     const Sk4f s4 = Sk4f::Load(src.fVec);
     const Sk4f dst_scale = Sk4f(1 - get_alpha(s4));
-    const Sk4f s4bias = unit_to_dst_bias<D>(s4);
+    const Sk4f s4bias = unit_to_bias<D>(s4);
     for (int i = 0; i < count; ++i) {
         const Sk4f d4bias = load_from_dst<D>(dst[i]);
         const Sk4f r4bias = s4bias + d4bias * dst_scale;
         if (aa) {
             dst[i] = store_to_dst<D>(lerp_by_coverage(r4bias, d4bias, aa[i]));
         } else {
             dst[i] = store_to_dst<D>(r4bias);
         }
     }
 }
 
 template <DstType D> void srcover_n(const SkXfermode::U64State& state, uint64_t dst[],
                                     const SkPM4f src[], int count, const SkAlpha aa[]) {
     for (int i = 0; i < count; ++i) {
         const Sk4f s4 = Sk4f::Load(src[i].fVec);
         const Sk4f dst_scale = Sk4f(1 - get_alpha(s4));
-        const Sk4f s4bias = unit_to_dst_bias<D>(s4);
+        const Sk4f s4bias = unit_to_bias<D>(s4);
         const Sk4f d4bias = load_from_dst<D>(dst[i]);
         const Sk4f r4bias = s4bias + d4bias * dst_scale;
         if (aa) {
             dst[i] = store_to_dst<D>(lerp_by_coverage(r4bias, d4bias, aa[i]));
         } else {
             dst[i] = store_to_dst<D>(r4bias);
         }
     }
 }
 
 const U64ProcPair gU64Procs_SrcOver[] = {
     { srcover_1<kU16_Dst>,  srcover_n<kU16_Dst> },   // U16     alpha
     { src_1<kU16_Dst>,      src_n<kU16_Dst>     },   // U16     opaque
     { srcover_1<kF16_Dst>,  srcover_n<kF16_Dst> },   // F16     alpha
     { src_1<kF16_Dst>,      src_n<kF16_Dst>     },   // F16     opaque
 };
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 static U64ProcPair find_procs(SkXfermode::Mode mode, uint32_t flags) {
     SkASSERT(0 == (flags & ~3));
     flags &= 3;
 
     switch (mode) {
         case SkXfermode::kSrc_Mode:     return gU64Procs_Src[flags];
         case SkXfermode::kSrcOver_Mode: return gU64Procs_SrcOver[flags];
         default:
             break;
     }
-    return { nullptr, nullptr };
+    return gU64Procs_General[flags];
 }
 
 SkXfermode::U64Proc1 SkXfermode::GetU64Proc1(Mode mode, uint32_t flags) {
     return find_procs(mode, flags).fP1;
 }
 
 SkXfermode::U64ProcN SkXfermode::GetU64ProcN(Mode mode, uint32_t flags) {
     return find_procs(mode, flags).fPN;
 }