Scroll to navigation

hal_malloc(3hal) HAL hal_malloc(3hal)


hal_malloc - Allocate space in the HAL shared memory area


void *hal_malloc(long int size)


Gives the size, in bytes, of the block.


hal_malloc allocates a block of memory from the main HAL shared memory area. It should be used by all components to allocate memory for HAL pins and parameters. It allocates `size' bytes, and returns a pointer to the allocated space, or NULL (0) on error. The returned pointer will be properly aligned for any type HAL supports. A component should allocate during initialization all the memory it needs.

The allocator is very simple, and there is no `free'. The entire HAL shared memory area is freed when the last component calls hal_exit. This means that if you continuously install and remove one component while other components are present, you eventually will fill up the shared memory and an install will fail. Removing all components completely clears memory and you start fresh.


A pointer to the allocated space, which is properly aligned for any variable HAL supports. Returns NULL on error.

2006-10-12 LinuxCNC Documentation