util/Clamp: generic Clamp() function

Makefile.am

@@ -248,6 +248,7 @@ endif
 
 libutil_a_SOURCES = \
 	src/util/Macros.hxx \
+	src/util/Clamp.hxx \
 	src/util/Error.cxx src/util/Error.hxx \
 	src/util/Domain.hxx \
 	src/util/ReusableArray.hxx \

src/mixer/AlsaMixerPlugin.cxx

@@ -27,6 +27,7 @@
 #include "event/Call.hxx"
 #include "util/ASCII.hxx"
 #include "util/ReusableArray.hxx"
+#include "util/Clamp.hxx"
 #include "util/Error.hxx"
 #include "util/Domain.hxx"
 #include "Log.hxx"
@@ -372,8 +373,7 @@ AlsaMixer::SetVolume(unsigned volume, Error &error)
 
 	level = (long)(((vol / 100.0) * (volume_max - volume_min) +
 			volume_min) + 0.5);
-	level = level > volume_max ? volume_max : level;
+	level = Clamp(level, volume_min, volume_max);
-	level = level < volume_min ? volume_min : level;
 
 	err = snd_mixer_selem_set_playback_volume_all(elem, level);
 	if (err < 0) {

src/pcm/PcmMix.cxx

@@ -23,6 +23,7 @@
 #include "PcmUtils.hxx"
 #include "AudioFormat.hxx"
 #include "Traits.hxx"
+#include "util/Clamp.hxx"
 
 #include <assert.h>
 #include <math.h>
@@ -215,7 +216,7 @@ pcm_mix(void *buffer1, const void *buffer2, size_t size,
 	s *= s;
 
 	vol1 = s * PCM_VOLUME_1 + 0.5;
-	vol1 = vol1 > PCM_VOLUME_1 ? PCM_VOLUME_1 : (vol1 < 0 ? 0 : vol1);
+	vol1 = Clamp<int>(vol1, 0, PCM_VOLUME_1);
 
 	return pcm_add_vol(buffer1, buffer2, size, vol1, PCM_VOLUME_1 - vol1, format);
 }

src/util/Clamp.hxx

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2012 Max Kellermann <max@duempel.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef CLAMP_HPP
+#define CLAMP_HPP
+
+#include "Compiler.h"
+
+/**
+ * Clamps the specified value in a range.  Returns #min or #max if the
+ * value is outside.
+ */
+template<typename T>
+static inline constexpr const T &
+Clamp(const T &value, const T &min, const T &max)
+{
+	return gcc_unlikely(value < min)
+		? min
+		: (gcc_unlikely(value > max)
+		   ? max : value);
+}
+
+#endif