1 files changed, 86 insertions, 0 deletions
diff --git a/shiny/driver/internal/swizzle/swizzle_test.go b/shiny/driver/internal/swizzle/swizzle_test.go
new file mode 100644
index 0000000..83a6d0c
--- /dev/null
+++ b/shiny/driver/internal/swizzle/swizzle_test.go
@@ -0,0 +1,86 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package swizzle
+
+import (
+	"bytes"
+	"math/rand"
+	"testing"
+)
+
+func TestBGRAShortInput(t *testing.T) {
+	const s = "012.456.89A.CDE.GHI.KLM.O"
+	testCases := []string{
+		0: "012.456.89A.CDE.GHI.KLM.O",
+		1: "210.456.89A.CDE.GHI.KLM.O",
+		2: "210.654.89A.CDE.GHI.KLM.O",
+		3: "210.654.A98.CDE.GHI.KLM.O",
+		4: "210.654.A98.EDC.GHI.KLM.O",
+		5: "210.654.A98.EDC.IHG.KLM.O",
+		6: "210.654.A98.EDC.IHG.MLK.O",
+	}
+	for i, want := range testCases {
+		b := []byte(s)
+		BGRA(b[:4*i])
+		got := string(b)
+		if got != want {
+			t.Errorf("i=%d: got %q, want %q", i, got, want)
+		}
+		changed := got != s
+		wantChanged := i != 0
+		if changed != wantChanged {
+			t.Errorf("i=%d: changed=%t, want %t", i, changed, wantChanged)
+		}
+	}
+}
+
+func TestBGRARandomInput(t *testing.T) {
+	r := rand.New(rand.NewSource(1))
+	fastBuf := make([]byte, 1024)
+	slowBuf := make([]byte, 1024)
+	for i := range fastBuf {
+		fastBuf[i] = uint8(r.Intn(256))
+	}
+	copy(slowBuf, fastBuf)
+
+	for i := 0; i < 100000; i++ {
+		o := r.Intn(len(fastBuf))
+		n := r.Intn(len(fastBuf)-o) &^ 0x03
+		BGRA(fastBuf[o : o+n])
+		pureGoBGRA(slowBuf[o : o+n])
+		if bytes.Equal(fastBuf, slowBuf) {
+			continue
+		}
+		for j := range fastBuf {
+			x := fastBuf[j]
+			y := slowBuf[j]
+			if x != y {
+				t.Fatalf("iter %d: swizzling [%d:%d+%d]: bytes differ at offset %d (aka %d+%d): %#02x vs %#02x",
+					i, o, o, n, j, o, j-o, x, y)
+			}
+		}
+	}
+}
+
+func pureGoBGRA(p []byte) {
+	if len(p)%4 != 0 {
+		return
+	}
+	for i := 0; i < len(p); i += 4 {
+		p[i+0], p[i+2] = p[i+2], p[i+0]
+	}
+}
+
+func benchmarkBGRA(b *testing.B, f func([]byte)) {
+	const w, h = 1920, 1080 // 1080p RGBA.
+	buf := make([]byte, 4*w*h)
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		f(buf)
+	}
+}
+
+func BenchmarkBGRA(b *testing.B)       { benchmarkBGRA(b, BGRA) }
+func BenchmarkPureGoBGRA(b *testing.B) { benchmarkBGRA(b, pureGoBGRA) }