_init_box

#include <rtl.h>

int _init_box  (
    void* box_mem,       /* Start address of the memory pool */
    U32   box_size,      /* Number of bytes in the memory pool */
    U32   blk_size );    /* Number of bytes in each block of the pool */

The _init_box function initializes a fixed block size memory pool. When the memory pool is initialized, the RTX kernel handles memory requests by allocating a block of memory from the memory pool.

The box_mem specifies the start address of the memory pool, and this address must be 4-byte aligned.

The box_size argument specifies the size of the memory pool, in bytes.

The blk_size argument specifies the size, in bytes, of the blocks in the memory pool. You can set the block size to any value from 1 to box_size-12. However, the blk_size is rounded up to the next multiple of 4 to maintain 4-byte address alignment of the blocks. For example if you initialize a memory pool for 10-byte blocks, the _init_box function actually initializes the memory pool for 12-byte blocks.

The _init_box function is in the RL-RTX library. The prototype is defined in rtl.h.

Note

• The first 12 bytes from the memory pool are reserved for storing pointers and size information that can be used by the functions that handle the memory pool. The box_size must therefore be more than 12 bytes long.
• If the start address is not 4-byte aligned, the memory pool handling functions might fail.

#include <rtl.h>

/* Reserve a memory for 32 blocks of 20-bytes. */
_declare_box(mpool,20,32);

void membox_test (void) {
   U8 *box;
   U8 *cbox;

   _init_box (mpool, sizeof (mpool), 20);
   box  = _alloc_box (mpool);
   /* This block is initialized to 0. */
   cbox = _calloc_box (mpool);
    .
    .
   _free_box (mpool, box);
   _free_box (mpool, cbox);
}