path: root/src/audio/internal.h

#ifndef AUDIO_INTERNAL_H
#define AUDIO_INTERNAL_H

#include <libultraship.h>
#include "common_structs.h"
#include "port/resource/type/AudioSequence.h"

#define SEQUENCE_PLAYERS 4
#define SEQUENCE_CHANNELS 48
#define SEQUENCE_LAYERS 64

#define LAYERS_MAX 4
#define CHANNELS_MAX 16

#define NO_LAYER ((struct SequenceChannelLayer*) (-1))

#define MUTE_BEHAVIOR_STOP_SCRIPT 0x80 // stop processing sequence/channel scripts
#define MUTE_BEHAVIOR_STOP_NOTES 0x40  // prevent further notes from playing
#define MUTE_BEHAVIOR_SOFTEN 0x20      // lower volume, by default to half

#define SEQUENCE_PLAYER_STATE_0 0
#define SEQUENCE_PLAYER_STATE_FADE_OUT 1
#define SEQUENCE_PLAYER_STATE_2 2
#define SEQUENCE_PLAYER_STATE_3 3
#define SEQUENCE_PLAYER_STATE_4 4

#define NOTE_PRIORITY_DISABLED 0
#define NOTE_PRIORITY_STOPPING 1
#define NOTE_PRIORITY_MIN 2
#define NOTE_PRIORITY_DEFAULT 3

#define TATUMS_PER_BEAT 48

// abi.h contains more details about the ADPCM and S8 codecs, "skip" skips codec processing
#define CODEC_ADPCM 0
#define CODEC_S8 1
#define CODEC_SKIP 2

#define TEMPO_SCALE TATUMS_PER_BEAT

//! @todo US_FLOAT should probably be renamed to JP_DOUBLE since eu seems to use floats too
#define US_FLOAT(x) x##f
#define US_FLOAT2(x) x

// Convert u8 or u16 to f32. On JP, this uses a u32->f32 conversion,
// resulting in more bloated codegen, while on US it goes through s32.
// Since u8 and u16 fit losslessly in both, behavior is the same.
#define FLOAT_CAST(x) (f32)(s32)(x)

// No-op printf macro which leaves string literals in rodata in IDO. IDO
// doesn't support variadic macros, so instead we let the parameter list
// expand to a no-op comma expression. Another possibility is that it might
// have expanded to something with "if (0)". See also goddard/gd_main.h.
// On US/JP, -sopt optimizes away these except for external.c.
#ifdef __sgi
#define stubbed_printf
#else
#define stubbed_printf(...)
#endif

#define eu_stubbed_printf_0(msg) stubbed_printf(msg)
#define eu_stubbed_printf_1(msg, a) stubbed_printf(msg, a)
#define eu_stubbed_printf_2(msg, a, b) stubbed_printf(msg, a, b)
#define eu_stubbed_printf_3(msg, a, b, c) stubbed_printf(msg, a, b, c)

struct NotePool;

struct AudioListItem {
    // A node in a circularly linked list. Each node is either a head or an item:
    // - Items can be either detached (prev = NULL), or attached to a list.
    //   'value' points to something of interest.
    // - List heads are always attached; if a list is empty, its head points
    //   to itself. 'count' contains the size of the list.
    // If the list holds notes, 'pool' points back to the pool where it lives.
    // Otherwise, that member is NULL.
    struct AudioListItem* prev;
    struct AudioListItem* next;
    union {
        void* value; // either Note* or SequenceChannelLayer*
        s32 count;
    } u;
    struct NotePool* pool;
}; // size = 0x10

struct NotePool {
    struct AudioListItem disabled;
    struct AudioListItem decaying;
    struct AudioListItem releasing;
    struct AudioListItem active;
};

struct VibratoState {
    /*0x00, 0x00*/ struct SequenceChannel* seqChannel;
    /*0x04, 0x04*/ u32 time;
    /*    , 0x08*/ s16* curve;
    /*    , 0x0C*/ f32 extent;
    /*    , 0x10*/ f32 rate;
    /*    , 0x14*/ u8 active;
    /*0x12, 0x16*/ u16 rateChangeTimer;
    /*0x14, 0x18*/ u16 extentChangeTimer;
    /*0x16, 0x1A*/ u16 delay;
}; // size = 0x18, 0x1C on EU

// Pitch sliding by up to one octave in the positive direction. Negative
// direction is "supported" by setting extent to be negative. The code
// extrapolates exponentially in the wrong direction in that case, but that
// doesn't prevent seqplayer from doing it, AFAICT.
struct Portamento {
    u8 mode; // bit 0x80 denotes something; the rest are an index 0-5
    f32 cur;
    f32 speed;
    f32 extent;
}; // size = 0x10

struct AdsrEnvelope {
    s16 delay;
    s16 arg;
}; // size = 0x4

struct AdpcmLoop {
    u32 start;
    u32 end;
    u32 count;
    u32 pad;
    s16* state; // only exists if count != 0. 8-byte aligned
};

struct AdpcmBook {
    s32 order;
    s32 npredictors;
    s16* book; // size 8 * order * npredictors. 8-byte aligned
};

struct AudioBankSample {
    u8 unused;
    u8 loaded;
    u8* sampleAddr;
    struct AdpcmLoop* loop;
    struct AdpcmBook* book;
    u32 sampleSize; // never read. either 0 or 1 mod 9, depending on padding
};

struct AudioBankSound {
    struct AudioBankSample* sample;
    f32 tuning; // frequency scale factor
}; // size = 0x8

struct Instrument {
    /*0x00*/ u8 loaded;
    /*0x01*/ u8 normalRangeLo;
    /*0x02*/ u8 normalRangeHi;
    /*0x03*/ u8 releaseRate;
    /*0x04*/ struct AdsrEnvelope* envelope;
    /*0x08*/ struct AudioBankSound lowNotesSound;
    /*0x10*/ struct AudioBankSound normalNotesSound;
    /*0x18*/ struct AudioBankSound highNotesSound;
}; // size = 0x20

struct Drum {
    /*0x00*/ u8 releaseRate;
    /*0x01*/ u8 pan;
    /*0x02*/ u8 loaded;
    struct AudioBankSound sound;
    struct AdsrEnvelope* envelope;
};

struct AudioBank {
    struct Drum** drums;
    struct Instrument* instruments[1];
}; // dynamic size

struct CtlEntry {
    u8 bankId;
    u8 numInstruments;
    u8 numDrums;
    struct Instrument** instruments;
    struct Drum** drums;
}; // size = 0xC

struct M64ScriptState {
    u8* pc;
    u8* stack[4];
    u8 remLoopIters[4];
    u8 depth;
}; // size = 0x1C

// Also known as a Group, according to debug strings.
struct SequencePlayer {
    /*US/JP, EU,    SH   */
    /*0x000, 0x000, 0x000*/ u8 enabled : 1;
    /*0x000, 0x000*/ u8 finished : 1; // never read
    /*0x000, 0x000*/ u8 muted : 1;
    /*0x000, 0x000*/ u8 seqDmaInProgress : 1;
    /*0x000, 0x000*/ u8 bankDmaInProgress : 1;
    /*       0x000*/ u8 recalculateVolume : 1;
    /*0x002, 0x001, 0x001*/ u8 state;
    /*0x003, 0x002*/ u8 noteAllocPolicy;
    /*0x004, 0x003*/ u8 muteBehavior;
    /*0x005, 0x004*/ u8 seqId;
    /*0x006, 0x005*/ u8 defaultBank[1]; // must be an array to get a comparison
                                        // to match; other u8's might also be part of that array
    /*0x007, 0x006*/ u8 loadingBankId;
    /*     , 0x007, 0x007*/ s8 seqVariationEu[1];
    /*0x00A, 0x008*/ u16 tempo; // beats per minute in JP, tatums per minute in US/EU
    /*0x00C, 0x00A*/ u16 tempoAcc;
    /*0x010, 0x00C, 0x00E*/ s16 transposition;
    /*0x012, 0x00E, 0x010*/ u16 delay;
    /*0x00E, 0x010, 0x012*/ u16 fadeRemainingFrames;
    /*     , 0x012, 0x014*/ u16 fadeTimerUnkEu;
    /*0x014, 0x014*/ u8* seqData;          // buffer of some sort
    /*0x018, 0x018, 0x1C*/ f32 fadeVolume; // set to 1.0f
    /*0x01C, 0x01C*/ f32 fadeVelocity;     // set to 0.0f
    /*0x020, 0x020, 0x024*/ f32 volume;    // set to 0.0f
    /*0x024, 0x024*/ f32 muteVolumeScale;  // set to 0.5f
    /*     , 0x028, 0x02C*/ f32 fadeVolumeScale;
    /*     , 0x02C*/ f32 appliedFadeVolume;
    /*0x02C, 0x030, 0x034*/ struct SequenceChannel* channels[CHANNELS_MAX];
    /*0x06C, 0x070*/ struct M64ScriptState scriptState;
    /*0x088, 0x08C*/ u8* shortNoteVelocityTable;
    /*0x08C, 0x090*/ u8* shortNoteDurationTable;
    /*0x090, 0x094*/ struct NotePool notePool;
    /*0x0D0, 0x0D4*/ OSMesgQueue seqDmaMesgQueue;
    /*0x0E8, 0x0EC*/ OSMesg seqDmaMesg;
    /*0x0EC, 0x0F0*/ OSIoMesg seqDmaIoMesg;
    /*0x100, 0x108*/ OSMesgQueue bankDmaMesgQueue;
    /*0x118, 0x120*/ OSMesg bankDmaMesg;
    /*0x11C, 0x124*/ OSIoMesg bankDmaIoMesg;
    /*0x130, 0x13C*/ u8* bankDmaCurrMemAddr;
    /*0x138, 0x140*/ uintptr_t bankDmaCurrDevAddr;
    /*0x13C, 0x144*/ size_t bankDmaRemaining;
}; // size = 0x140, 0x148 on EU, 0x14C on SH

struct AdsrSettings {
    u8 releaseRate;
    u8 sustain;
    struct AdsrEnvelope* envelope;
}; // size = 0x8

struct AdsrState {
    /*0x00, 0x00*/ u8 action;
    /*0x01, 0x01*/ u8 state;
    /*0x08, 0x02*/ s16 envIndex;
    /*0x0A, 0x04*/ s16 delay;
    /*    , 0x08*/ f32 sustain;
    /*    , 0x0C*/ f32 velocity;
    /*    , 0x10*/ f32 fadeOutVel;
    /*    , 0x14*/ f32 current;
    /*    , 0x18*/ f32 target;
    s32 pad1C;
    /*0x1C, 0x20*/ struct AdsrEnvelope* envelope;
}; // size = 0x20, 0x24 in EU

struct ReverbBitsData {
    /* 0x00 */ u8 bit0 : 1;
    /* 0x00 */ u8 bit1 : 1;
    /* 0x00 */ u8 bit2 : 1;
    /* 0x00 */ u8 usesHeadsetPanEffects : 1;
    /* 0x00 */ u8 stereoHeadsetEffects : 2;
    /* 0x00 */ u8 strongRight : 1;
    /* 0x00 */ u8 strongLeft : 1;
};

union ReverbBits {
    /* 0x00 */ struct ReverbBitsData s;
    /* 0x00 */ u8 asByte;
};
struct ReverbInfo {
    u8 reverbVol;
    u8 synthesisVolume; // UQ4.4, although 0 <= x < 1 is rounded up to 1
    u8 pan;
    union ReverbBits reverbBits;
    f32 freqScale;
    f32 velocity;
    s32 unused;
    s16* filter;
};

struct NoteAttributes {
    u8 reverbVol;
    u8 pan;
    f32 freqScale;
    f32 velocity;
}; // size = 0x10

// Also known as a SubTrack, according to debug strings.
// Confusingly, a SubTrack is a container of Tracks.
struct SequenceChannel {
    /* U/J, EU,   SH  */
    /*0x00, 0x00*/ u8 enabled : 1;
    /*0x00, 0x00*/ u8 finished : 1;
    /*0x00, 0x00*/ u8 stopScript : 1;
    /*0x00, 0x00*/ u8 stopSomething2 : 1; // sets SequenceChannelLayer.stopSomething
    /*0x00, 0x00*/ u8 hasInstrument : 1;
    /*0x00, 0x00*/ u8 stereoHeadsetEffects : 1;
    /*0x00, ????*/ u8 largeNotes : 1; // notes specify duration and velocity
    /*0x00, ????*/ u8 unused : 1;     // never read, set to 0
    /*    , 0x01*/ union {
        struct {
            u8 freqScale : 1;
            u8 volume : 1;
            u8 pan : 1;
        } as_bitfields;
        u8 as_u8;
    } changes;
    /*0x01, 0x02*/ u8 noteAllocPolicy;
    /*0x02, 0x03, 0x03*/ u8 muteBehavior;
    /*0x03, 0x04, 0x04*/ u8 reverbVol; // until EU: Q1.7, after EU: UQ0.8
    /*0x04, ????*/ u8 notePriority;    // 0-3
    /*0x05, 0x06*/ u8 bankId;
    /*    , 0x07*/ u8 reverbIndex;
    /*    , 0x08, 0x09*/ u8 bookOffset;
    /*    , 0x09*/ u8 newPan;
    /*    , 0x0A*/ u8 panChannelWeight;        // proportion of pan that comes from the channel (0..128)
    /*0x08, 0x0C, 0x0E*/ u16 vibratoRateStart; // initially 0x800
    /*0x0A, 0x0E, 0x10*/ u16 vibratoExtentStart;
    /*0x0C, 0x10, 0x12*/ u16 vibratoRateTarget; // initially 0x800
    /*0x0E, 0x12, 0x14*/ u16 vibratoExtentTarget;
    /*0x10, 0x14, 0x16*/ u16 vibratoRateChangeDelay;
    /*0x12, 0x16, 0x18*/ u16 vibratoExtentChangeDelay;
    /*0x14, 0x18, 0x1A*/ u16 vibratoDelay;
    /*0x16, 0x1A, 0x1C*/ u16 delay;
    /*0x18, 0x1C, 0x1E*/ s16 instOrWave; // either 0 (none), instrument index + 1, or
                                         // 0x80..0x83 for sawtooth/triangle/sine/square waves.
    /*0x1A, 0x1E, 0x20*/ s16 transposition;
    /*0x1C, 0x20, 0x24*/ f32 volumeScale;
    /*0x20, 0x24, 0x28*/ f32 volume;
    /*    , 0x28*/ s32 pan;
    /*    , 0x2C*/ f32 appliedVolume;
    /*0x2C, 0x30*/ f32 freqScale;
    /*0x30, 0x34*/ u8 (*dynTable)[][2];
    /*0x34, ????*/ struct Note* noteUnused;                  // never read
    /*0x38, ????*/ struct SequenceChannelLayer* layerUnused; // never read
    /*0x3C, 0x40*/ struct Instrument* instrument;
    /*0x40, 0x44*/ struct SequencePlayer* seqPlayer;
    /*0x44, 0x48*/ struct SequenceChannelLayer* layers[LAYERS_MAX];
    /*0x54, 0x58      */ s8 soundScriptIO[8]; // bridge between sound script and audio lib. For player 2,
    // [0] contains enabled, [4] contains sound ID, [5] contains reverb adjustment
    /*0x5C, 0x60*/ struct M64ScriptState scriptState;
    /*0x78, 0x7C*/ struct AdsrSettings adsr;
    /*0x80, 0x84*/ struct NotePool notePool;
    /*          */ u8 surroundEffectIndex; // Surround depth: 0 = front, 0x7F = behind
}; // size = 0xC0, 0xC4 in EU, 0xD0 in SH

// Also known as a Track, according to debug strings.
struct SequenceChannelLayer {
    /* U/J, EU,  SH */
    /*0x00, 0x00*/ u8 enabled : 1;
    /*0x00, 0x00*/ u8 finished : 1;
    /*0x00, 0x00*/ u8 stopSomething : 1;   // ?
    /*0x00, 0x00*/ u8 continuousNotes : 1; // keep the same note for consecutive notes with the same sound
    /*    , 0x00*/ u8 unusedEu0b8 : 1;
    /*    , 0x00*/ u8 notePropertiesNeedInit : 1;
    /*    , 0x00*/ u8 ignoreDrumPan : 1;
    /*    , 0x01, 0x02*/ u8 instOrWave;
    /*0x01, 0x02, 0x03*/ u8 status; // 0x03 in SH
    /*0x02, 0x03*/ u8 noteDuration; // set to 0x80
    /*0x03, 0x04*/ u8 portamentoTargetNote;
    /*    , 0x05*/ u8 pan; // 0..128
    /*    , 0x06, 0x07*/ u8 notePan;
    /*0x04, 0x08*/ struct Portamento portamento;
    /*0x14, 0x18*/ struct AdsrSettings adsr;
    /*0x1C, 0x20*/ u16 portamentoTime;
    /*0x1E, 0x22*/ s16 transposition; // #semitones added to play commands
                                      // (m64 instruction encoding only allows referring to the limited range
                                      // 0..0x3f; this makes 0x40..0x7f accessible as well)
    /*0x20, 0x24, 0x24*/ f32 freqScale;
    /*0x24, 0x28, 0x2C*/ f32 velocitySquare;
    /*0x2C, 0x2C, 0x30*/ f32 noteVelocity;
    /*0x34, 0x30, 0x34*/ f32 noteFreqScale;
    /*0x38, 0x34*/ s16 shortNoteDefaultPlayPercentage;
    /*0x3A, 0x36*/ s16 playPercentage; // it's not really a percentage...
    /*0x3C, 0x38*/ s16 delay;
    /*0x3E, 0x3A*/ s16 duration;
    /*0x40, 0x3C*/ s16 delayUnused; // set to 'delay', never read
    /*0x44, 0x40, 0x44*/ struct Note* note;
    /*0x48, 0x44*/ struct Instrument* instrument;
    /*0x4C, 0x48*/ struct AudioBankSound* sound;
    /*0x50, 0x4C, 0x50*/ struct SequenceChannel* seqChannel;
    /*0x54, 0x50*/ struct M64ScriptState scriptState;
    /*0x70, 0x6C*/ struct AudioListItem listItem;
    u8 pad2[4];
}; // size = 0x80

struct NoteSynthesisState {
    /*0x00*/ u8 restart;
    /*0x01*/ u8 sampleDmaIndex;
    /*0x02*/ u8 prevHeadsetPanRight;
    /*0x03*/ u8 prevHeadsetPanLeft;
    /*0x04, 0x06*/ u16 samplePosFrac;
    /*0x08*/ s32 samplePosInt;
    /*0x0C*/ struct NoteSynthesisBuffers* synthesisBuffers;
    /*0x10*/ s16 curVolLeft;  // UQ0.16 (EU Q1.15)
    /*0x12*/ s16 curVolRight; // UQ0.16 (EU Q1.15)
};
struct NotePlaybackState {
    /* U/J, EU,   SH  */
    /*0x04, 0x00, 0x00*/ u8 priority;
    /*      0x01, 0x01*/ u8 waveId;
    /*      0x02, 0x02*/ u8 sampleCountIndex;
    /*0x08, 0x04, 0x06*/ s16 adsrVolScale;
    /*0x18, 0x08, 0x08*/ f32 portamentoFreqScale;
    /*0x1C, 0x0C, 0x0C*/ f32 vibratoFreqScale;
    /*0x28, 0x10,     */ struct SequenceChannelLayer* prevParentLayer;
    /*0x2C, 0x14, 0x14*/ struct SequenceChannelLayer* parentLayer;
    /*0x30, 0x18, 0x18*/ struct SequenceChannelLayer* wantedParentLayer;
    /*    , 0x1C, 0x1C*/ struct NoteAttributes attributes;
    /*0x54, 0x28, 0x2C*/ struct AdsrState adsr;
    /*0x74, 0x4C,     */ struct Portamento portamento;
    /*0x84, 0x5C,     */ struct VibratoState vibratoState;
};
struct NoteSubEu {
    /*0x00*/ volatile u8 enabled : 1;
    /*0x00*/ u8 needsInit : 1;
    /*0x00*/ u8 finished : 1;
    /*0x00*/ u8 envMixerNeedsInit : 1;
    /*0x00*/ u8 stereoStrongRight : 1;
    /*0x00*/ u8 stereoStrongLeft : 1;
    /*0x00*/ u8 stereoHeadsetEffects : 1;
    /*0x00*/ u8 usesHeadsetPanEffects : 1;
    /*0x01*/ u8 reverbIndex : 3;
    /*0x01*/ u8 bookOffset : 3;
    /*0x01*/ u8 isSyntheticWave : 1;
    /*0x01*/ u8 hasTwoAdpcmParts : 1;
    /*0x02*/ u8 bankId;
    /*0x03*/ u8 headsetPanRight;
    /*0x04*/ u8 headsetPanLeft;
    /*0x05*/ u8 reverbVol;                 // UQ0.7 (EU Q1.7)
    /*0x06*/ u16 targetVolLeft;            // UQ0.12 (EU UQ0.10)
    /*0x08*/ u16 targetVolRight;           // UQ0.12 (EU UQ0.10)
    /*0x0A*/ u16 resamplingRateFixedPoint; // stored as signed but loaded as u16
    /*0x0C*/ union {
        s16* samples;
        struct AudioBankSound* audioBankSound;
    } sound;
};
struct Note {
    /* U/J,  EU,  SH  */
    /*0xA4, 0x00, 0x00*/ struct AudioListItem listItem;
    /*      0x10, 0x10*/ struct NoteSynthesisState synthesisState;
    // The next members are actually part of a struct (NotePlaybackState), but
    // that results in messy US/EU ifdefs. Instead we cast to a struct pointer
    // when needed... This breaks alignment on non-N64 platforms, which we hack
    // around by skipping the padding in that case.
    //! @todo use macros or something instead.
#ifdef TARGET_N64
    u8 pad0[12];
#endif

    /*0x04, 0x30, 0x30*/ u8 priority;
    /*      0x31, 0x31*/ u8 waveId;
    /*      0x32, 0x32*/ u8 sampleCountIndex;
    /*0x08, 0x34, 0x36*/ s16 adsrVolScale;
    /*0x18, 0x38,     */ f32 portamentoFreqScale;
    /*0x1C, 0x3C,     */ f32 vibratoFreqScale;
    /*0x28, 0x40,     */ struct SequenceChannelLayer* prevParentLayer;
    /*0x2C, 0x44, 0x44*/ struct SequenceChannelLayer* parentLayer;
    /*0x30, 0x48, 0x48*/ struct SequenceChannelLayer* wantedParentLayer;
    /*    , 0x4C, 0x4C*/ struct NoteAttributes attributes;
    /*0x54, 0x58, 0x5C*/ struct AdsrState adsr;
    /*0x74, 0x7C*/ struct Portamento portamento;
    /*0x84, 0x8C*/ struct VibratoState vibratoState;
    u8 pad3[8];
    /*    , 0xB0, 0xB4*/ struct NoteSubEu noteSubEu;
    /*          */ u8 surroundEffectIndex; // Surround depth: 0 = front, 0x7F = behind
    /*          */ u8 notePan;             // Pan position for surround effect (0=left, 128=center, 255=right)
}; // size = 0xC0, known to be 0xC8 on SH

// While this struct needs to be size 0xA0, its not clear
// what innards are necessary. All the possible options from
// SM64 are sized incorrectly so we're probably looking at some
// MK64 weirdness
struct NoteSynthesisBuffers {
    s16 adpcmdecState[0x10];
    s16 finalResampleState[0x10];
    s16 panResampleState[0x10];
    s16 panSamplesBuffer[0x20];
}; // size = 0xA0

/*
SM64 NoteSynthesisBuffers, kept here because I'm not sure our current
version is correct
struct NoteSynthesisBuffers {
    s16 adpcmdecState[0x10];
    s16 finalResampleState[0x10];
#ifdef VERSION_SH
    s16 unk[0x10];
    s16 filterBuffer[0x20];
    s16 panSamplesBuffer[0x20];
#else
    s16 mixEnvelopeState[0x28];
    s16 panResampleState[0x10];
    s16 panSamplesBuffer[0x20];
    s16 dummyResampleState[0x10];
#if defined(VERSION_JP) || defined(VERSION_US)
    s16 samples[0x40];
#endif
#endif
};
*/

struct ReverbSettingsEU {
    u8 downsampleRate;
    u8 windowSize; // To be multiplied by 64
    u16 gain;
};

struct AudioSessionSettingsEU {
    /* 0x00 */ u32 frequency;
    /* 0x04 */ u8 unk1; // always 1
    /* 0x05 */ u8 maxSimultaneousNotes;
    /* 0x06 */ u8 numReverbs; // always 1
    /* 0x07 */ u8 unk2;       // always 0
    /* 0x08 */ struct ReverbSettingsEU* reverbSettings;
    /* 0x0C */ u16 volume;
    /* 0x0E */ u16 unk3; // always 0
    /* 0x10 */ u32 persistentSeqMem;
    /* 0x14 */ u32 persistentBankMem;
    /* 0x18 */ u32 unk_18;
    /* 0x1C */ u32 temporarySeqMem;
    /* 0x20 */ u32 temporaryBankMem;
    /* 0x24 */ u32 unk_24;
}; // 0x30 on shindou

struct AudioSessionSettings {
    /*0x00*/ u32 frequency;
    /*0x04*/ u8 maxSimultaneousNotes;
    /*0x05*/ u8 reverbDownsampleRate; // always 1
    /*0x06*/ u16 reverbWindowSize;
    /*0x08*/ u16 reverbGain;
    /*0x0A*/ u16 volume;
    /*0x0C*/ u32 persistentSeqMem;
    /*0x10*/ u32 persistentBankMem;
    /*0x14*/ u32 temporarySeqMem;
    /*0x18*/ u32 temporaryBankMem;
}; // size = 0x1C

struct AudioBufferParametersEU {
    /*0x00*/ s16 presetUnk4; // audio frames per vsync?
    /*0x02*/ u16 frequency;
    /*0x04*/ u16 aiFrequency; // ?16
    /*0x06*/ s16 samplesPerFrameTarget;
    /*0x08*/ s16 maxAiBufferLength;
    /*0x0A*/ s16 minAiBufferLength;
    /*0x0C*/ s16 updatesPerFrame;
    /*0x0E*/ s16 samplesPerUpdate;
    /*0x10*/ s16 samplesPerUpdateMax;
    /*0x12*/ s16 samplesPerUpdateMin;
    /*0x14*/ f32 resampleRate;             // contains 32000.0f / frequency
    /*0x18*/ f32 updatesPerFrameInv;       // 1.0f / updatesPerFrame
    /*0x1C*/ f32 unkUpdatesPerFrameScaled; // 3.0f / (1280.0f * updatesPerFrame)
};

/**
 * This definition comes from SM64. For reasons not fully understood
 * eu_process_audio_cmd does not match properly if this definition
 * is used.
 * We're either:
 *     Missing a compiler -D for IS_BIG_ENDIAN
 *     or
 *     The version of that function in MK64 is significantly different
 *     from its SM64 counterpart
 * Or we just have a poor understanding of this part of the system.
**/

struct EuAudioCmd {
    union {
#if IS_BIG_ENDIAN
        struct {
            u8 op;
            u8 bankId;
            u8 arg2;
            u8 arg3;
        } s;
#else
        struct {
            u8 arg3;
            u8 arg2;
            u8 bankId;
            u8 op;
        } s;
#endif
        s32 first;
    } u;
    union {
        s32 as_s32;
        u32 as_u32;
        f32 as_f32;
#if IS_BIG_ENDIAN
        u8 as_u8;
        s8 as_s8;
#else
        struct {
            u8 pad0[3];
            u8 as_u8;
        };
        struct {
            u8 pad1[3];
            s8 as_s8;
        };
#endif
    } u2;
};

extern void create_next_audio_buffer(s16* samples, u32 num_samples);

#endif // AUDIO_INTERNAL_H