test and fix f16<->f32 conversion stages

This refactors from_half() and to_half() a bit, totally
reimplementing the non-hardware cases to be more clearly correct.

CQ_INCLUDE_TRYBOTS=skia.primary:Test-Android-Clang-PixelC-CPU-TegraX1-arm64-Release-Android,Test-Android-Clang-Ci20-CPU-IngenicJZ4780-mipsel-Release-Android,Test-Android-Clang-Nexus10-CPU-Exynos5250-arm-Release-Android,Test-Mac-Clang-MacMini6.2-CPU-AVX-x86_64-Release,Test-Ubuntu-GCC-GCE-CPU-AVX2-x86-Debug,Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Debug

Change-Id: I439463cf90935c5e8fe2369cbcf45e07f3af62c7
Reviewed-on: https://skia-review.googlesource.com/13921
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Matt Sarett <msarett@google.com>

1 files changed, 53 insertions, 0 deletions

diff --git a/tests/F16StagesTest.cpp b/tests/F16StagesTest.cpp
new file mode 100644
index 0000000000..73072e3870
--- /dev/null
+++ b/tests/F16StagesTest.cpp
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkRasterPipeline.h"
+#include "Test.h"
+
+DEF_TEST(F16Stages, r) {
+    // Make sure SkRasterPipeline::load_f16 and store_f16 can handle a range of
+    // ordinary (0<=x<=1) and interesting (x<0, x>1) values.
+    float floats[16] = {
+        0.0f, 0.25f, 0.5f, 1.0f,
+        -1.25f, -0.5f, 1.25f, 2.0f,
+        0,0,0,0, 0,0,0,0,  // pad a bit to make sure we qualify for platform-specific code
+    };
+    uint16_t halfs[16] = {0,0,0,0, 0,0,0,0, 0,0,0,0, 0,0,0,0};
+
+    float*    f32 = floats;
+    uint16_t* f16 = halfs;
+
+    {
+        SkRasterPipeline p;
+        p.append(SkRasterPipeline:: load_f32, &f32);
+        p.append(SkRasterPipeline::store_f16, &f16);
+        p.run(0,16/4);
+    }
+    REPORTER_ASSERT(r, f16[0] == 0x0000);
+    REPORTER_ASSERT(r, f16[1] == 0x3400);
+    REPORTER_ASSERT(r, f16[2] == 0x3800);
+    REPORTER_ASSERT(r, f16[3] == 0x3c00);
+    REPORTER_ASSERT(r, f16[4] == 0xbd00);
+    REPORTER_ASSERT(r, f16[5] == 0xb800);
+    REPORTER_ASSERT(r, f16[6] == 0x3d00);
+    REPORTER_ASSERT(r, f16[7] == 0x4000);
+
+    {
+        SkRasterPipeline p;
+        p.append(SkRasterPipeline:: load_f16, &f16);
+        p.append(SkRasterPipeline::store_f32, &f32);
+        p.run(0,16/4);
+    }
+    REPORTER_ASSERT(r, f32[0] ==  0.00f);
+    REPORTER_ASSERT(r, f32[1] ==  0.25f);
+    REPORTER_ASSERT(r, f32[2] ==  0.50f);
+    REPORTER_ASSERT(r, f32[3] ==  1.00f);
+    REPORTER_ASSERT(r, f32[4] == -1.25f);
+    REPORTER_ASSERT(r, f32[5] == -0.50f);
+    REPORTER_ASSERT(r, f32[6] ==  1.25f);
+    REPORTER_ASSERT(r, f32[7] ==  2.00f);
+}