Dynamic Memory Allocation Glossary

ALLOCATE ( u -- a-addr ior )

Allocate u address units of contiguous data space. The data-space pointer is unaffected by this operation. The initial content of the allocated space is undefined.

If the allocation succeeds, a-addr is the aligned starting address of the allocated space and ior is zero. If the operation fails, a-addr does not represent a valid address and ior is the result code -8 (dictionary overflow).

EMPTY-MEMORY ( addr size -- )

Initialize the dynamic memory allocation system to manage the memory starting at addr and of size u. Before allocating dynamic memory EMPTY-MEMORY has to be invoked with an appropriate available memory region.

FREE ( a-addr -- ior )

Return the contiguous region of data space indicated by a-addr to the system for later allocation. a-addr shall indicate a region of data space that was previously obtained by ALLOCATE or RESIZE. The data-space pointer is unaffected by this operation.

If the operation succeeds, ior is zero. If the operation fails, ior is a result code identfiying the error.

RESIZE ( a-addr1 u -- a-addr2 ior )

Change the allocation of the contiguous data space starting at the address a-addr1, previously allocated by ALLOCATE or RESIZE, to u address units. u may be either larger or smaller than the current size of the region. The data-space pointer is unaffected by this operation.

If the operation succeeds, a-addr2 is the aligned starting address of u address units of allocated memory and ior is zero. a-addr2 may be, but need not be, the same as a-addr1. If they are not the same, the values contained in the region at a-addr1 are copied to a-addr2, up to the minimum size of either of the two regions. If they are the same, the values contained in the region are preserved to the minimum of u or the original size. If a-addr2 is not the same as a-addr1, the region of memory at a-addr1 is returned to the system according to the operation of FREE.

If the operation fails, a-addr2 equals a-addr1, the region of memory at a-addr1 is unaffected, and ior is the result code -8 (dictionary overflow).

SIZE ( mem -- size )

Determine the allocation size of the memory block mem. mem must be previously allocated by ALLOCATE or RESIZE.