SonicForgeStudio/native_bridge/include/SharedMemoryIPC.h

// native_bridge/include/SharedMemoryIPC.h
#pragma once
#include <cstdint>
#include <cstddef>

#ifdef _WIN32
#include <windows.h>
#endif

#define AUDIO_BLOCK_SIZE 256

// WARNING: volatile is NOT a sync primitive. Real impl should use an
// interlocked/index-flag pair or a Win32 event (SetEvent) signalled by the
// writer. This struct follows the spec layout so Rust/JS mapping stays in sync.
struct SharedAudioBufferIPC {
    // Synchronization Flags
    volatile uint32_t clientReadIndex;
    volatile uint32_t bridgeWriteIndex;

    // PCM Float32 Audio Buffers
    float masterLeft[AUDIO_BLOCK_SIZE];
    float masterRight[AUDIO_BLOCK_SIZE];

    // Latency probe: bridge stamps every rendered block (QueryPerformanceCounter)
    volatile uint64_t blockTimestamp;

    // MIDI Event Exchange Queue
    struct MidiEventIPC {
        uint8_t command;      // 0x9 note on / 0x8 note off / 0xB CC / 0xC program / 0xE pitch bend
        uint8_t channel;
        uint8_t pitch;        // note number (0x9/0x8) or CC number (0xB)
        uint8_t velocity;     // 0-127 (0x9 + vel=0 == note off)
        uint8_t data2;        // CC value / program number / PB LSB
        uint8_t data3;        // PB MSB (0xE only)
        uint8_t reserved[2];  // reserved[0]: live flag (1 = live input, bypass transportStopped guard); reserved[1]: 0 — keeps C/Rust layout stable
        uint32_t sampleOffset;
    } midiQueue[64];

    volatile uint32_t midiQueueCount;

    // Transport / Control (added vs spec: Stop/Play flush, instrument switch)
    struct ControlEventIPC {
        uint32_t type;        // 0 = NONE, 1 = PANIC/ALL_NOTES_OFF, 2 = LOAD_INSTRUMENT,
                              // 3 = TRANSPORT, 4 = OPEN_GUI
        uint32_t arg0;        // LOAD: instrument type (InstrumentType);
                              // TRANSPORT: 0=STOP, 1=PLAY, 2=SET_POSITION
        uint32_t arg1;        // LOAD: string length (bytes) of path;
                              // TRANSPORT: playheadSamples (for timeline sync)
        uint32_t channel;     // LOAD: MIDI channel to assign instrument to (A10)
        char     arg2[1024];  // LOAD: UTF-8 path
    } controlQueue[8];
    volatile uint32_t controlQueueCount;

    // G0.3: set by the bridge while an openGUI attach job is in flight
    // (reload/attachView on a ChannelWorker). The Tauri watchdog reads this
    // to extend its stall deadline — a long Nexus attach must not look like
    // a dead bridge. Append-only field: existing offsets stay stable.
    volatile uint32_t attachInFlight;

    // G3.1: dedicated heartbeat, incremented every 100ms by a bridge-side
    // thread INDEPENDENT of the audio loop. The Tauri watchdog keys bridge
    // liveness on this, so a slow (but alive) audio loop no longer looks dead.
    // Append-only field: existing offsets stay stable.
    volatile uint32_t heartbeat;

    // VSTi crackle fix: multi-slot audio ring (appended after heartbeat — all
    // offsets above stay stable). The bridge renders block N into slot
    // (bridgeWriteIndex & ringMask), then increments bridgeWriteIndex (publish).
    // The reader drains EVERY slot between its last index and writeIndex, in
    // order, so a delayed reader no longer loses a whole block to single-slot
    // overwrite (the old 1-slot gap). ringMask = slot count - 1 (power of 2);
    // 8 slots ~= 42ms of audio @ 48k — covers a pump/WebView jank window.
    volatile uint32_t ringMask;
    float ringLeft[8][AUDIO_BLOCK_SIZE];
    float ringRight[8][AUDIO_BLOCK_SIZE];

    // A14: MIDI OUT from plugins (VST2 audioMaster opcode=8 VstEvents,
    // VST3 IEventList output bus). The bridge writes events the plugin
    // generated; the Tauri pump drains them to `bridge-midi-out` and the
    // JS routes them to DAW tracks. Append-only field: all offsets above
    // stay stable.
    MidiEventIPC midiOutQueue[64];
    volatile uint32_t midiOutCount;
};

// G4.3: per-plugin sandbox SHM — double-buffered audio handoff.
// The child renders into the slot it is NOT publishing (writeSlot flips),
// then publishes; the bridge reads the published slot. A stale slot is safe
// to read (bridge keeps last block), so a slow child never tears audio.
// G4.5: preset blob round-trip for VST2 sandbox children. jBridge romplers
// like Kong Audio Qin_RV render SILENT from factory state - they need their
// program/bank chunk restored (bridge_state presetBase64). presetIn is
// bridge->child (base64 text; presetInLen>0 = pending, child applies and
// zeroes it). presetOut is child->bridge: the child republishes its chunk
// after load / preset apply / GUI edit, so the bridge can persist it.
#define PRESET_BLOB_SIZE 65536
struct SandboxHostIPC {
    SharedAudioBufferIPC base;            // MIDI/control/heartbeat, offsets unchanged
    volatile uint32_t writeSlot;          // 0 or 1: slot the child finished writing
    float audioLeft[2][AUDIO_BLOCK_SIZE]; // 2 full blocks
    float audioRight[2][AUDIO_BLOCK_SIZE];
    char presetIn[PRESET_BLOB_SIZE];      // bridge -> child (base64 text)
    volatile uint32_t presetInLen;        // >0: pending; child applies + zeroes
    char presetOut[PRESET_BLOB_SIZE];     // child -> bridge (base64 text)
    volatile uint32_t presetOutLen;       // 0 = none published yet
};

// Shared-memory helpers (impl in SharedMemoryIPC.cpp).
struct ShmHandle;
ShmHandle* shm_open(const char* name, size_t size = sizeof(SharedAudioBufferIPC));
ShmHandle* shm_create(const char* name, size_t size = sizeof(SharedAudioBufferIPC));
SharedAudioBufferIPC* shm_ptr(ShmHandle* h);
SandboxHostIPC* shm_sandbox_ptr(ShmHandle* h);
void shm_close(ShmHandle* h);
bool shm_write_midi(ShmHandle* h, uint8_t cmd, uint8_t channel, uint8_t pitch,
                    uint8_t velocity, uint32_t sampleOffset, uint8_t data2 = 0,
                    uint8_t data3 = 0);