DosSubSet

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

DosSubSet (SegSelector, Flags, Size)

• 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.

rc (USHORT) - return

Return code descriptions are:

• 0 NO_ERROR
• 310 ERROR_DOSSUB_SHRINK
• 313 ERROR_DOSSUB_BADSIZE
• 314 ERROR_DOSSUB_BADFLAG

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.

#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 */

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

Text based on http://www.edm2.com/index.php/DosSubSet