DosSubAlloc

This call suballocates portions of a segment allocated by DosAllocSeg or DosAllocShrSeg, and initialized by DosSubSet.

Syntax

DosSubAlloc (SegSelector, BlockOffset, Size)

Parameters

SegSelector (SEL) - input

Data segment selector that allocates the memory.

BlockOffset (PUSHORT) - output

Address of the allocated block offset.

Size (USHORT) - input

Memory block size requested in bytes.

Return Code

rc (USHORT) - return

Return code descriptions are:

• 0 NO_ERROR
• 311 ERROR_DOSSUB_NOMEM
• 313 ERROR_DOSSUB_BADSIZE

Remarks

Before a segment allocated by DosAllocSeg or DosAllocShrSeg can be suballocated, it must first be initialized for suballocation by a call to DosSubSet.

Allocation size must be a multiple of four bytes. Otherwise, it is rounded up to a multiple of four bytes. The maximum value for the size parameter is the size that was set with DosSubSet minus 8. Note that no paragraph (16-byte) alignment is required; all requests are serviced on a byte alignment basis.

A suballocated block of memory in a suballocated segment is freed by a call to DosSubFree.

Example Code

C Binding

#define INCL_DOSMEMMGR

USHORT  rc = DosSubAlloc(SegSelector, BlockOffset, Size);

SEL     SegSelector;   /* Segment selector */
PUSHORT BlockOffset;   /* Block Offset (returned) */
USHORT  Size;          /* Size of requested block */

USHORT  rc;            /* return code */

MASM Binding

EXTRN  DosSubAlloc:FAR
INCL_DOSMEMMGR      EQU 1

PUSH   WORD    SegSelector   ;Segment selector
PUSH@  WORD    BlockOffset   ;Block Offset (returned)
PUSH   WORD    Size          ;Size of requested block
CALL   DosSubAlloc

Returns WORD

Related Functions

• DosSubSet