Create AudioOutput singleton, from extracted BasebandProcessor code.

firmware/baseband/audio_output.hpp

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+/*
+ * Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
+ *
+ * This file is part of PortaPack.
+ *
+ * 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, 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; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __AUDIO_OUTPUT_H__
+#define __AUDIO_OUTPUT_H__
+
+#include "dsp_types.hpp"
+
+#include "dsp_iir.hpp"
+#include "dsp_squelch.hpp"
+
+#include "audio_stats_collector.hpp"
+
+#include <cstdint>
+
+class AudioOutput {
+public:
+	void configure(
+		const iir_biquad_config_t& hpf_config,
+		const iir_biquad_config_t& deemph_config = iir_config_passthrough,
+		const uint32_t squelch_threshold = 0
+	);
+
+	void write(const buffer_s16_t& audio);
+
+private:
+	IIRBiquadFilter hpf;
+	IIRBiquadFilter deemph;
+	FMSquelch squelch;
+
+	AudioStatsCollector audio_stats;
+
+	void fill_audio_buffer(const buffer_s16_t& audio);
+	void feed_audio_stats(const buffer_s16_t& audio);
+};
+
+extern AudioOutput audio_output;
+
+#endif/*__AUDIO_OUTPUT_H__*/