An implementation of ALLOCATE FREE RESIZE in Forth-94
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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
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
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
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
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