Segfault with function in macro - allowed in Max?

Hi there,

Working on bringing another very cool library into Max but have run into a big nasty brick wall. My C++ is even worse than my C, so please take this with a grain of salt.

One of the class files (.cc) I'm working with has this:

void homography_estimator::reset_correspondences(int maximum_number_of_correspondences)
{
  manage_buffer(u_v_up_vp,            4 * maximum_number_of_correspondences, float);
  manage_buffer(normalized_u_v_up_vp, 4 * maximum_number_of_correspondences, float);
  manage_buffer(scores,                   maximum_number_of_correspondences, float); //

Manage_buffer does something I've never seen before. It defines the functions in the macros. I don't think this is a coincidence that it crashes here.

// Macros for the functions defined above:
#define manage_buffer(buffer, required_size, type)            
  if ((buffer) != 0 && ( *(int*)(((char*)(buffer)) - sizeof(void*) - sizeof(int)) < (required_size)) ) { 
    aligned_and_managed_delete(buffer);                    
    (buffer) = 0;                            
  }                                    
  if ((buffer) == 0) {                            
    int size = (required_size) * sizeof(type);                
    buffer = (type*)(aligned_and_managed_new16b(size));            
    if (MANAGED_MEMORY_DEBUGGING)                    
      cout << endl                            
       << "[MANAGED_MEMORY_DEBUGGING: allocating "            
       << (required_size) << " x " << sizeof(type)            
       << " bytes at t" << (void*)(buffer) << "]" << endl;        
    if ((buffer) == 0)                            
      cerr << ">! [buffer_management] MACRO manage_buffer: can't alloc " << size << " bytes." << endl; 
    else                                
      *(int*)(((char*)buffer) - sizeof(void*) - sizeof(int)) = required_size; 
  }

Is it something within the function I'm not understanding that's causing the problem, or is declaring the function in a macro not compatible with the way Max/MSP works?

Any help is appreciated.

Thanks.