audio_core/hle: Refactor Binary Pipe data structures

audio_core\hle\ffmpeg_decoder.cpp: renames

src/audio_core/hle/decoder.h

@@ -14,18 +14,22 @@
 namespace AudioCore::HLE {
 
 enum class DecoderCommand : u16 {
-    Init,
-    Decode,
-    Unknown,
+    Init = 0,
+    EncodeDecode = 1,
+    Unknown = 2, // Probably UnInit
 };
 
 enum class DecoderCodec : u16 {
-    None,
-    AAC,
+    None = 0,
+    DecodeAAC = 1,
+    EncodeAAC = 2,
+};
+
+enum class ResultStatus : u32 {
+    Success = 0,
+    Error = 1,
 };
 
-// TODO(xperia64): I'm guessing that this is a u32 (from when it was an unknown)
-// but it could be a u16 or u8 I suppose
 enum class DecoderSampleRate : u32 {
     Rate48000 = 0,
     Rate44100 = 1,
@@ -38,40 +42,96 @@ enum class DecoderSampleRate : u32 {
     Rate8000 = 8
 };
 
-struct BinaryRequest {
-    enum_le<DecoderCodec> codec =
-        DecoderCodec::None; // this is a guess. until now only 0x1 was observed here
-    enum_le<DecoderCommand> cmd = DecoderCommand::Init;
-    u32_le fixed = 0;
+// The DSP replies with the same contents as the response too.
+struct DecodeAACInitRequest {
+    u32_le unknown1 = 0; // observed 1 here
+    u32_le unknown2 = 0; // observed -1 here
+    u32_le unknown3 = 0; // observed 1 here
+    u32_le unknown4 = 0; // observed 0 here
+    u32_le unknown5 = 0; // unused? observed 1 here
+    u32_le unknown6 = 0; // unused? observed 0x20 here
+};
+
+struct DecodeAACRequest {
     u32_le src_addr = 0;
     u32_le size = 0;
     u32_le dst_addr_ch0 = 0;
     u32_le dst_addr_ch1 = 0;
-    u32_le unknown1 = 0;
-    u32_le unknown2 = 0;
+    u32_le unknown1 = 0; // unused?
+    u32_le unknown2 = 0; // unused?
 };
-static_assert(sizeof(BinaryRequest) == 32, "Unexpected struct size for BinaryRequest");
 
-struct BinaryResponse {
-    enum_le<DecoderCodec> codec =
-        DecoderCodec::None; // this could be something else. until now only 0x1 was observed here
-    enum_le<DecoderCommand> cmd = DecoderCommand::Init;
-    u32_le unknown1 = 0;
+struct DecodeAACResponse {
     enum_le<DecoderSampleRate> sample_rate;
     u32_le num_channels = 0; // this is a guess, so far I only observed 2 here
     u32_le size = 0;
-    u32_le unknown3 = 0;
-    u32_le unknown4 = 0;
+    u32_le unknown1 = 0;
+    u32_le unknown2 = 0;
     u32_le num_samples = 0; // this is a guess, so far I only observed 1024 here
 };
-static_assert(sizeof(BinaryResponse) == 32, "Unexpected struct size for BinaryResponse");
+
+// The DSP replies with the same contents as the response too.
+struct EncodeAACInitRequest {
+    u32_le unknown1 =
+        0; // 0:raw 1:ADTS? less than 2 according to the 3DS Sound app. observed 1 here
+    enum_le<DecoderSampleRate> sample_rate =
+        DecoderSampleRate::Rate16000; // the rate the 3DS Sound app uses
+    u32_le unknown3 =
+        0; // Num channels? less than 3 according to the 3DS Sound app. observed 2 here
+    u32_le unknown4 = 0; // less than 2 according to the 3DS Sound app. observed 0 here
+    u32_le unknown5 = 0; // unused?
+    u32_le unknown6 = 0; // unused?
+};
+
+struct EncodeAACRequest {
+    u32_le src_addr_ch0 = 0;
+    u32_le src_addr_ch1 = 0;
+    u32_le dst_addr = 0;
+    u32_le unknown1 = 0; // the 3DS Sound app explicitly moves 0x003B'4A08, possibly an address
+    u32_le unknown2 = 0; // unused?
+    u32_le unknown3 = 0; // unused?
+};
+
+struct EncodeAACResponse {
+    u32_le unknown1 = 0;
+    u32_le unknown2 = 0;
+    u32_le unknown3 = 0;
+    u32_le unknown4 = 0;
+    u32_le unknown5 = 0; // unused?
+    u32_le unknown6 = 0; // unused?
+};
+
+struct BinaryMessage {
+    struct {
+        enum_le<DecoderCodec> codec =
+            DecoderCodec::None; // this is a guess. until now only 0x1 was observed here
+        enum_le<DecoderCommand> cmd = DecoderCommand::Init;
+        // This is a guess, when tested with Init EncodeAAC, the DSP replies 0x0 for apparently
+        // valid values and 0x1 (regardless of what was passed in the request) for invalid values in
+        // other fields
+        enum_le<ResultStatus> result = ResultStatus::Error;
+    } header;
+    union {
+        std::array<u8, 24> data{};
+
+        DecodeAACInitRequest decode_aac_init;
+        DecodeAACRequest decode_aac_request;
+        DecodeAACResponse decode_aac_response;
+
+        EncodeAACInitRequest encode_aac_init;
+        EncodeAACRequest encode_aac_request;
+        EncodeAACResponse encode_aac_response;
+    };
+};
+
+static_assert(sizeof(BinaryMessage) == 32, "Unexpected struct size for BinaryMessage");
 
 enum_le<DecoderSampleRate> GetSampleRateEnum(u32 sample_rate);
 
 class DecoderBase {
 public:
     virtual ~DecoderBase();
-    virtual std::optional<BinaryResponse> ProcessRequest(const BinaryRequest& request) = 0;
+    virtual std::optional<BinaryMessage> ProcessRequest(const BinaryMessage& request) = 0;
     /// Return true if this Decoder can be loaded. Return false if the system cannot create the
     /// decoder
     virtual bool IsValid() const = 0;
@@ -81,7 +141,7 @@ class NullDecoder final : public DecoderBase {
 public:
     NullDecoder();
     ~NullDecoder() override;
-    std::optional<BinaryResponse> ProcessRequest(const BinaryRequest& request) override;
+    std::optional<BinaryMessage> ProcessRequest(const BinaryMessage& request) override;
     bool IsValid() const override {
         return true;
     }