### _umalloc -- Reserve Memory Blocks from User Heap

Format

>     #include <umalloc.h>
>     void *_umalloc(Heap_t heap, size_t size);

Language Level: Extension
_umalloc allocates a memory block of size bytes from the heap you specify. Unlike _ucalloc, _umalloc does not initialize all bits to 0.

_umalloc works just like malloc, except that you specify the heap to use; malloc always allocates from the default heap. A debug version of this function, _debug_umalloc, is also provided.

If the heap does not have enough memory for the request, _umalloc calls the getmore_fn that you specified when you created the heap with _ucreate.

To reallocate or free memory allocated with _umalloc, use the non-heap-specific realloc and free. These functions always check what heap the memory was allocated from.

Return Value
_umalloc returns a pointer to the reserved space. If size was specified as 0, or if your getmore_fn cannot provide enough memory, _umalloc returns NULL. Passing _umalloc a heap that is not valid results in undefined behavior.

Example
This example creates a heap and uses _umalloc to allocate memory from the heap.

    #include <stdlib.h>
    #include <stdio.h>
    #include <umalloc.h>

    int main(void)
    {
       Heap_t  myheap;
       char    *ptr;

       /* Use default heap as user heap */
       myheap = _udefault(NULL);

       if (NULL == (ptr = (char*)_umalloc(myheap, 100))) {
          puts("Cannot allocate memory from user heap.");
          exit(EXIT_FAILURE);
       }
       free(ptr);
       return 0;
    }

Memory Management

calloc -- Reserve and Initialize Storage
_debug_umalloc -- Reserve Memory Blocks from User Heap
free -- Release Storage Blocks
malloc -- Reserve Storage Block
realloc -- Change Reserved Storage Block Size
_ucalloc -- Reserve and Initialize Memory from User Heap
_ucreate -- Create a Memory Heap
<umalloc.h>