DosSubSet

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This call is used to initialize a segment or to reset a reallocated segment for suballocation.

Syntax

DosSubSet (SegSelector, Flags, Size)

Parameters

SegSelector (SEL) - input 
Target data segment selector.
Flags (USHORT) - input
0 = Increasing the size of a segment already initialized.
1 = Initializing a segment.
Size (USHORT) - input 
Segment size in bytes.

Return Code

rc (USHORT) - return
Return code descriptions are:
  • 0 NO_ERROR
  • 310 ERROR_DOSSUB_SHRINK
  • 313 ERROR_DOSSUB_BADSIZE
  • 314 ERROR_DOSSUB_BADFLAG

Remarks

To initialize a segment for suballocation, issue DosSubSet before issuing DosSubAlloc and set Flags = 1. The segment must have been allocated with DosAllocSeg or DosAllocShrSeg.

If a segment allocated by a DosAllocSeg call has already been set for suballocation, and a call to DosSubAlloc returns Error_DOSSUB_NOMEM, the segment's size can be increased by a call to DosReallocSeg. After reallocation, the segment must be reset by a DosSubSet. Failure to reset the segment after changing its size can yield unpredictable results.

The size parameter should be a multiple of four bytes, or it is rounded up to a multiple of four. Note in DosSubSet, a size parameter of 0 indicates the segment is 64KB, while in DosSubAlloc and DosSubFree, a size parameter of 0 is an error. Other than this special case of 0 meaning 64KB, the minimum size that can be set is 12 bytes.

Bindings

C

#define INCL_DOSMEMMGR

USHORT  rc = DosSubSet(SegSelector, Flags, Size);

SEL     SegSelector;   /* Segment selector */
USHORT  Flags;         /* Parameter flags */
USHORT  Size;          /* Size of a block */

USHORT  rc;            /* return code */

MASM

EXTRN  DosSubSet:FAR
INCL_DOSMEMMGR      EQU 1

PUSH   WORD    SegSelector   ;Segment selector
PUSH   WORD    Flags         ;Parameter flags
PUSH   WORD    Size          ;Size of a segment
CALL   DosSubSet

Returns WORD