test/test_pcm: add unit test for pcm_mix()

Makefile.am

@@ -1407,6 +1407,7 @@ test_test_pcm_SOURCES = \
 	test/test_pcm_channels.cxx \
 	test/test_pcm_format.cxx \
 	test/test_pcm_volume.cxx \
+	test/test_pcm_mix.cxx \
 	test/test_pcm_all.hxx \
 	test/test_pcm_main.cxx
 test_test_pcm_LDADD = \

test/test_pcm_all.hxx

@@ -65,4 +65,16 @@ test_pcm_format_16_to_32();
 void
 test_pcm_format_float();
 
+void
+test_pcm_mix_8();
+
+void
+test_pcm_mix_16();
+
+void
+test_pcm_mix_24();
+
+void
+test_pcm_mix_32();
+
 #endif

test/test_pcm_main.cxx

@@ -43,5 +43,10 @@ main(int argc, char **argv)
 	g_test_add_func("/pcm/format/16_to_32", test_pcm_format_16_to_32);
 	g_test_add_func("/pcm/format/float", test_pcm_format_float);
 
+	g_test_add_func("/pcm/mix/8", test_pcm_mix_8);
+	g_test_add_func("/pcm/mix/16", test_pcm_mix_16);
+	g_test_add_func("/pcm/mix/24", test_pcm_mix_24);
+	g_test_add_func("/pcm/mix/32", test_pcm_mix_32);
+
 	g_test_run();
 }

test/test_pcm_mix.cxx

@@ -0,0 +1,84 @@
+/*
+ * 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 "config.h"
+#include "test_pcm_all.hxx"
+#include "test_pcm_util.hxx"
+#include "PcmMix.hxx"
+
+#include <glib.h>
+
+template<typename T, sample_format format, typename G=GlibRandomInt<T>>
+void
+TestPcmMix(G g=G())
+{
+	constexpr unsigned N = 256;
+	const auto src1 = TestDataBuffer<T, N>(g);
+	const auto src2 = TestDataBuffer<T, N>(g);
+
+	/* portion1=1.0: result must be equal to src1 */
+	auto result = src1;
+	bool success = pcm_mix(result.begin(), src2.begin(), sizeof(result),
+			       format, 1.0);
+	g_assert(success);
+	AssertEqualWithTolerance(result, src1, 1);
+
+	/* portion1=0.0: result must be equal to src2 */
+	result = src1;
+	success = pcm_mix(result.begin(), src2.begin(), sizeof(result),
+			  format, 0.0);
+	g_assert(success);
+	AssertEqualWithTolerance(result, src2, 1);
+
+	/* portion1=0.5 */
+	result = src1;
+	success = pcm_mix(result.begin(), src2.begin(), sizeof(result),
+			  format, 0.5);
+	g_assert(success);
+
+	auto expected = src1;
+	for (unsigned i = 0; i < N; ++i)
+		expected[i] = (int64_t(src1[i]) + int64_t(src2[i])) / 2;
+
+	AssertEqualWithTolerance(result, expected, 1);
+}
+
+void
+test_pcm_mix_8()
+{
+	TestPcmMix<int8_t, SAMPLE_FORMAT_S8>();
+}
+
+void
+test_pcm_mix_16()
+{
+	TestPcmMix<int16_t, SAMPLE_FORMAT_S16>();
+}
+
+void
+test_pcm_mix_24()
+{
+	TestPcmMix<int32_t, SAMPLE_FORMAT_S24_P32>(GlibRandomInt24());
+}
+
+void
+test_pcm_mix_32()
+{
+	TestPcmMix<int32_t, SAMPLE_FORMAT_S32>();
+}

test/test_pcm_util.hxx

@@ -51,6 +51,7 @@ template<typename T, size_t N>
 class TestDataBuffer : std::array<T, N> {
 public:
 	using typename std::array<T, N>::const_pointer;
+	using std::array<T, N>::size;
 	using std::array<T, N>::begin;
 	using std::array<T, N>::end;
 	using std::array<T, N>::operator[];
@@ -66,3 +67,19 @@ public:
 		return begin();
 	}
 };
+
+template<typename T>
+bool
+AssertEqualWithTolerance(const T &a, const T &b, unsigned tolerance)
+{
+	g_assert_cmpint(a.size(), ==, b.size());
+
+	for (unsigned i = 0; i < a.size(); ++i) {
+		int64_t x = a[i], y = b[i];
+
+		g_assert_cmpint(x, >=, y - int64_t(tolerance));
+		g_assert_cmpint(x, <=, y + int64_t(tolerance));
+	}
+
+	return true;
+}