From 2a99464ef1a35cb97cb94636d99779caa34f3cb7 Mon Sep 17 00:00:00 2001
From: MerryMage <MerryMage@users.noreply.github.com>
Date: Sat, 26 Mar 2016 02:20:34 +0000
Subject: DSP: Implement audio filters (simple, biquad)

---
 src/audio_core/hle/filter.h | 112 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)
 create mode 100644 src/audio_core/hle/filter.h

(limited to 'src/audio_core/hle/filter.h')

diff --git a/src/audio_core/hle/filter.h b/src/audio_core/hle/filter.h
new file mode 100644
index 000000000..75738f600
--- /dev/null
+++ b/src/audio_core/hle/filter.h
@@ -0,0 +1,112 @@
+// Copyright 2016 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <array>
+
+#include "audio_core/hle/common.h"
+#include "audio_core/hle/dsp.h"
+
+#include "common/common_types.h"
+
+namespace DSP {
+namespace HLE {
+
+/// Preprocessing filters. There is an independent set of filters for each Source.
+class SourceFilters final {
+    SourceFilters() { Reset(); }
+
+    /// Reset internal state.
+    void Reset();
+
+    /**
+     * Enable/Disable filters
+     * See also: SourceConfiguration::Configuration::simple_filter_enabled,
+     *           SourceConfiguration::Configuration::biquad_filter_enabled.
+     * @param simple If true, enables the simple filter. If false, disables it.
+     * @param simple If true, enables the biquad filter. If false, disables it.
+     */
+    void Enable(bool simple, bool biquad);
+
+    /**
+     * Configure simple filter.
+     * @param config Configuration from DSP shared memory.
+     */
+    void Configure(SourceConfiguration::Configuration::SimpleFilter config);
+
+    /**
+     * Configure biquad filter.
+     * @param config Configuration from DSP shared memory.
+     */
+    void Configure(SourceConfiguration::Configuration::BiquadFilter config);
+
+    /**
+     * Processes a frame in-place.
+     * @param frame Audio samples to process. Modified in-place.
+     */
+    void ProcessFrame(StereoFrame16& frame);
+
+private:
+    bool simple_filter_enabled;
+    bool biquad_filter_enabled;
+
+    struct SimpleFilter {
+        SimpleFilter() { Reset(); }
+
+        /// Resets internal state.
+        void Reset();
+
+        /**
+         * Configures this filter with application settings.
+         * @param config Configuration from DSP shared memory.
+         */
+        void Configure(SourceConfiguration::Configuration::SimpleFilter config);
+
+        /**
+         * Processes a single stereo PCM16 sample.
+         * @param x0 Input sample
+         * @return Output sample
+         */
+        std::array<s16, 2> ProcessSample(const std::array<s16, 2>& x0);
+
+    private:
+        // Configuration
+        s32 a1, b0;
+        // Internal state
+        std::array<s16, 2> y1;
+    } simple_filter;
+
+    struct BiquadFilter {
+        BiquadFilter() { Reset(); }
+
+        /// Resets internal state.
+        void Reset();
+
+        /**
+         * Configures this filter with application settings.
+         * @param config Configuration from DSP shared memory.
+         */
+        void Configure(SourceConfiguration::Configuration::BiquadFilter config);
+
+        /**
+         * Processes a single stereo PCM16 sample.
+         * @param x0 Input sample
+         * @return Output sample
+         */
+        std::array<s16, 2> ProcessSample(const std::array<s16, 2>& x0);
+
+    private:
+        // Configuration
+        s32 a1, a2, b0, b1, b2;
+        // Internal state
+        std::array<s16, 2> x1;
+        std::array<s16, 2> x2;
+        std::array<s16, 2> y1;
+        std::array<s16, 2> y2;
+    } biquad_filter;
+};
+
+} // namespace HLE
+} // namespace DSP
-- 
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