Proof of concept for accessing gmem data from REAPER extensions using eel_gmem_attach

reaper_gmem.cpp

#include "reaper_plugin.h"

#define EEL_F_SIZE WDL_FFT_REALSIZE
#include "WDL/WDL/eel2/nseel-ram.c"

EEL_F *** (*eel_gmem_attach)(const char *nm, bool is_alloc);
void (*eel_enter_mutex)();
void (*eel_leave_mutex)();

void NSEEL_HOSTSTUB_EnterMutex() { eel_enter_mutex(); }
void NSEEL_HOSTSTUB_LeaveMutex() { eel_leave_mutex(); }

class eel_gmem_space {
public:
  eel_gmem_space(const char *name) : m_space{eel_gmem_attach(name, true)} {}

  EEL_F read(const int index) const
  {
    EEL_F *slot = __NSEEL_RAMAllocGMEM(m_space, index);
    return slot ? *slot : 0;
  }

  void write(const int index, const EEL_F value)
  {
    if(EEL_F *slot = __NSEEL_RAMAllocGMEM(m_space, index))
      *slot = value;
  }

private:
  EEL_F ***m_space;
};

extern "C" REAPER_PLUGIN_DLL_EXPORT int REAPER_PLUGIN_ENTRYPOINT(
  REAPER_PLUGIN_HINSTANCE instance, reaper_plugin_info_t *rec)
{
  if(!rec || rec->caller_version != REAPER_PLUGIN_VERSION)
    return 0;

  eel_gmem_attach = (decltype(eel_gmem_attach))rec->GetFunc("eel_gmem_attach");
  eel_enter_mutex = (decltype(eel_enter_mutex))rec->GetFunc("NSEEL_HOSTSTUB_EnterMutex");
  eel_leave_mutex = (decltype(eel_leave_mutex))rec->GetFunc("NSEEL_HOSTSTUB_LeaveMutex");

  eel_gmem_space foobar("foobar");
  foobar.write(42, 4.2);

  return 1;
}

No, because it requires shipping an implementation of EEL's RAMAllocGMEM assuming it perfectly matches the one compiled inside of REAPER, which is inherently unsafe.

Ah good point. I currently write global memory to sliders and read it off there. Not an amazing solution but seems to work.