Using the C Math Library

Replacing Allocation and Deallocation Routines

The MATLAB C Math Library calls mxMalloc to allocate memory and mxFree to free memory. These routines in turn call the standard C runtime library routines malloc and free.

If your application requires a different memory management implementation, you can register your allocation and deallocation routines with the MATLAB C Math Library by calling the function mlfSetLibraryAllocFcns().

void mlfSetLibraryAllocFcns(calloc_proc calloc_fcn,
                            free_proc free_fcn,
                            realloc_proc realloc_fcn,
                            malloc_proc malloc_fcn);

You must write four functions whose addresses you then pass to mlfSetLibraryAllocFcns():

• calloc_fcn is the name of the function that mxCalloc uses to perform memory allocation operations. The function that you write must have the prototype:

void * callocfcn(size_t nmemb, size_t size);

Your function should initialize the memory it allocates to 0 and should return NULL for requests of size 0.

• free_fcn is the name of the function that mxFree uses to perform memory deallocation (freeing) operations. The function that you write must have the prototype:

void freefcn(void *ptr);

Make sure your function handles NULL pointers. free_fcn(0) should do nothing.

• realloc_fcn is the name of the function that mxRealloc uses to perform memory reallocation operations. The function that you write must have the prototype:

void * reallocfcn(void *ptr, size_t size);

This function must grow or shrink memory. It returns a pointer to the requested amount of memory, which contains as much as possible of the previous contents.

• malloc_fcn is the name of the function to be called in place of malloc to perform memory allocation operations. The prototype for your function must match:

void * mallocfcn(size_t n);

Your function should return NULL for requests of size 0.

Refer to the MATLAB Application Program Interface Reference online help for more detailed information about writing these functions.

Restrictions

Indexing into Arrays