1 files changed, 82 insertions, 0 deletions
diff --git a/test/test_pcm_dither.cxx b/test/test_pcm_dither.cxx
new file mode 100644
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--- /dev/null
+++ b/test/test_pcm_dither.cxx
@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "test_pcm_all.hxx"
+
+extern "C" {
+#include "pcm_dither.h"
+}
+
+#include <glib.h>
+
+/**
+ * Generate a random 24 bit PCM sample.
+ */
+static int32_t
+random24()
+{
+	int32_t x = g_random_int() & 0xffffff;
+	if (x & 0x800000)
+		x |= 0xff000000;
+	return x;
+}
+
+void
+test_pcm_dither_24()
+{
+	struct pcm_dither dither;
+
+	pcm_dither_24_init(&dither);
+
+	enum { N = 256 };
+	int32_t src[N];
+	for (unsigned i = 0; i < N; ++i)
+		src[i] = random24();
+
+	int16_t dest[N];
+
+	pcm_dither_24_to_16(&dither, dest, src, src + N);
+
+	for (unsigned i = 0; i < N; ++i) {
+		g_assert_cmpint(dest[i], >=, (src[i] >> 8) - 8);
+		g_assert_cmpint(dest[i], <, (src[i] >> 8) + 8);
+	}
+}
+
+void
+test_pcm_dither_32()
+{
+	struct pcm_dither dither;
+
+	pcm_dither_24_init(&dither);
+
+	enum { N = 256 };
+	int32_t src[N];
+	for (unsigned i = 0; i < N; ++i)
+		src[i] = g_random_int();
+
+	int16_t dest[N];
+
+	pcm_dither_32_to_16(&dither, dest, src, src + N);
+
+	for (unsigned i = 0; i < N; ++i) {
+		g_assert_cmpint(dest[i], >=, (src[i] >> 16) - 8);
+		g_assert_cmpint(dest[i], <, (src[i] >> 16) + 8);
+	}
+}