pcm_*: move to src/pcm/

src/pcm/PcmMix.hxx

@@ -0,0 +1,49 @@
+/*
+ * 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.
+ */
+
+#ifndef MPD_PCM_MIX_HXX
+#define MPD_PCM_MIX_HXX
+
+#include "audio_format.h"
+#include "gcc.h"
+
+#include <stddef.h>
+
+/*
+ * Linearly mixes two PCM buffers.  Both must have the same length and
+ * the same audio format.  The formula is:
+ *
+ *   s1 := s1 * portion1 + s2 * (1 - portion1)
+ *
+ * @param buffer1 the first PCM buffer, and the destination buffer
+ * @param buffer2 the second PCM buffer
+ * @param size the size of both buffers in bytes
+ * @param format the sample format of both buffers
+ * @param portion1 a number between 0.0 and 1.0 specifying the portion
+ * of the first buffer in the mix; portion2 = (1.0 - portion1). The value
+ * NaN is used by the MixRamp code to specify that simple addition is required.
+ *
+ * @return true on success, false if the format is not supported
+ */
+gcc_warn_unused_result
+bool
+pcm_mix(void *buffer1, const void *buffer2, size_t size,
+	enum sample_format format, float portion1);
+
+#endif