SkRasterPipeline preliminaries

tests/SkRasterPipelineTest.cpp

Index: tests/SkRasterPipelineTest.cpp
diff --git a/tests/SkRasterPipelineTest.cpp b/tests/SkRasterPipelineTest.cpp
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+++ b/tests/SkRasterPipelineTest.cpp
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+/*
+ * 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 "Test.h"
+#include "SkRasterPipeline.h"
+
+// load needs two variants, one to load 4 values...
+static void SK_VECTORCALL load(SkRasterPipeline::Stage* st, size_t x,
+                               Sk4f v0, Sk4f v1, Sk4f v2, Sk4f v3,
+                               Sk4f v4, Sk4f v5, Sk4f v6, Sk4f v7) {
+    auto ptr = st->ctx<const float*>();
+    v0 = Sk4f{ptr[x+0]};
+    v1 = Sk4f{ptr[x+1]};
+    v2 = Sk4f{ptr[x+2]};
+    v3 = Sk4f{ptr[x+3]};
+
+    st->next(x, v0,v1,v2,v3, v4,v5,v6,v7);
+}
+
+// ...and one to load a single value.
+static void SK_VECTORCALL load_tail(SkRasterPipeline::Stage* st, size_t x,
+                                    Sk4f v0, Sk4f v1, Sk4f v2, Sk4f v3,
+                                    Sk4f v4, Sk4f v5, Sk4f v6, Sk4f v7) {
+    auto ptr = st->ctx<const float*>();
+    v0 = Sk4f{ptr[x]};
+
+    st->next(x, v0,v1,v2,v3, v4,v5,v6,v7);
+}
+
+// square doesn't really care how many of its inputs are active, nor does it need a context.
+static void SK_VECTORCALL square(SkRasterPipeline::Stage* st, size_t x,
+                                 Sk4f v0, Sk4f v1, Sk4f v2, Sk4f v3,
+                                 Sk4f v4, Sk4f v5, Sk4f v6, Sk4f v7) {
+    v0 *= v0;
+    v1 *= v1;
+    v2 *= v2;
+    v3 *= v3;
+    st->next(x, v0,v1,v2,v3, v4,v5,v6,v7);
+}
+
+// Like load, store has a _tail variant.  It ends the pipeline by returning.
+static void SK_VECTORCALL store(SkRasterPipeline::Stage* st, size_t x,
+                                Sk4f v0, Sk4f v1, Sk4f v2, Sk4f v3,
+                                Sk4f v4, Sk4f v5, Sk4f v6, Sk4f v7) {
+    auto ptr = st->ctx<float*>();
+    ptr[x+0] = v0[0];
+    ptr[x+1] = v1[0];
+    ptr[x+2] = v2[0];
+    ptr[x+3] = v3[0];
+}
+
+static void SK_VECTORCALL store_tail(SkRasterPipeline::Stage* st, size_t x,
+                                     Sk4f v0, Sk4f v1, Sk4f v2, Sk4f v3,
+                                     Sk4f v4, Sk4f v5, Sk4f v6, Sk4f v7) {
+    auto ptr = st->ctx<float*>();
+    ptr[x+0] = v0[0];
+}
+
+DEF_TEST(SkRasterPipeline, r) {
+    // We'll build up and run a simple pipeline that exercises the salient
+    // mechanics of SkRasterPipeline:
+    //    - context pointers
+    //    - stages sensitive to the number of pixels
+    //    - stages insensitive to the number of pixels
+    //
+    // This pipeline loads up some values, squares them, then writes them back to memory.
+
+    const float src_vals[] = { 1,2,3,4,5 };
+    float       dst_vals[] = { 0,0,0,0,0 };
+
+    SkRasterPipeline p;
+    p.append(load, load_tail, src_vals);
+    p.append(square);
+    p.append(store, store_tail, dst_vals);
+
+    p.run(5);
+
+    REPORTER_ASSERT(r, dst_vals[0] ==  1);
+    REPORTER_ASSERT(r, dst_vals[1] ==  4);
+    REPORTER_ASSERT(r, dst_vals[2] ==  9);
+    REPORTER_ASSERT(r, dst_vals[3] == 16);
+    REPORTER_ASSERT(r, dst_vals[4] == 25);
+}