Implement a high-level emulation of the MP2K audio mixer. (#170)

src/CMakeLists.txt

@@ -20,6 +20,7 @@ set(SOURCES
   emulator/core/hw/apu/channel/noise_channel.cpp
   emulator/core/hw/apu/channel/quad_channel.cpp
   emulator/core/hw/apu/channel/wave_channel.cpp
+  emulator/core/hw/apu/hle/mp2k.cpp
   emulator/core/hw/apu/apu.cpp
   emulator/core/hw/apu/callback.cpp
   emulator/core/hw/apu/registers.cpp
@@ -49,6 +50,7 @@ set(HEADERS
   common/dsp/resampler/windowed-sinc.hpp
   common/dsp/resampler.hpp
   common/compiler.hpp
+  common/crc32.hpp
   common/integer.hpp
   common/compiler.hpp
   common/log.hpp
@@ -89,6 +91,7 @@ set(HEADERS
   emulator/core/hw/apu/channel/quad_channel.hpp
   emulator/core/hw/apu/channel/sweep.hpp
   emulator/core/hw/apu/channel/wave_channel.hpp
+  emulator/core/hw/apu/hle/mp2k.hpp
   emulator/core/hw/apu/apu.hpp
   emulator/core/hw/apu/registers.hpp
   emulator/core/hw/ppu/helper.inl

src/common/crc32.hpp

@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2021 fleroviux
+ *
+ * Licensed under GPLv3 or any later version.
+ * Refer to the included LICENSE file.
+ */
+
+#include <common/integer.hpp>
+
+inline u32 crc32(u8 const* data, int length) {
+  u32 crc32 = 0xFFFFFFFF;
+
+  while (length-- != 0) {
+    u8 byte = *data++;
+
+    // TODO: speed this up using a lookup table.
+    for (int i = 0; i < 8; i++) {
+      if ((crc32 ^ byte) & 1) {
+        crc32 = (crc32 >> 1) ^ 0xEDB88320;
+      } else {
+        crc32 >>= 1;
+      }
+      byte >>= 1;
+    }
+  }
+
+  return ~crc32;
+}

src/common/dsp/resampler/windowed-sinc.hpp

@@ -29,7 +29,7 @@ struct SincResampler : Resampler<T> {
     Resampler<T>::SetSampleRates(samplerate_in, samplerate_out);
 
     float kernelSum = 0.0;
-    float cutoff = 1.0;//0.9;
+    float cutoff = 0.9;
 
     if (this->resample_phase_shift > 1.0) {
       cutoff /= this->resample_phase_shift;

src/emulator/config/config.hpp

@@ -54,7 +54,8 @@ struct Config {
       Sinc_256
     } interpolation = Interpolation::Cosine;
     bool interpolate_fifo = true;
-    bool m4a_xq_enable = false;
+    bool mp2k_hle_enable = false;
+    bool mp2k_hle_cubic = false;
   } audio;
 
   std::shared_ptr<AudioDevice> audio_dev = std::make_shared<NullAudioDevice>();

src/emulator/config/config_toml.cpp

@@ -110,7 +110,8 @@ void config_toml_read(Config& config, std::string const& path) {
       }
 
       config.audio.interpolate_fifo = toml::find_or<toml::boolean>(audio, "interpolate_fifo", true);
-      config.audio.m4a_xq_enable = toml::find_or<toml::boolean>(audio, "m4a_xq_enable", false);
+      config.audio.mp2k_hle_enable = toml::find_or<toml::boolean>(audio, "mp2k_hle_enable", false);
+      config.audio.mp2k_hle_cubic = toml::find_or<toml::boolean>(audio, "mp2k_hle_cubic", false);
     }
   }
 }
@@ -163,7 +164,8 @@ void config_toml_write(Config& config, std::string const& path) {
   }
   data["audio"]["resampler"] = resampler;
   data["audio"]["interpolate_fifo"] = config.audio.interpolate_fifo;
-  data["audio"]["m4a_xq_enable"] = config.audio.m4a_xq_enable;
+  data["audio"]["mp2k_hle_enable"] = config.audio.mp2k_hle_enable;
+  data["audio"]["mp2k_hle_cubic"] = config.audio.mp2k_hle_cubic;
 
   std::ofstream file{ path, std::ios::out };
   file << data;