DosGetSeg

This call accesses shared memory allocated by a DosAllocSeg or DosAllocHuge call.

Syntax

DosGetSeg (Selector)

Parameters

Selector (SEL) - input

Parameter used to get access to a segment.

Return Code

rc (USHORT) - return

Return code descriptions are:

• 0 NO_ERROR
• 5 ERROR_ACCESS_DENIED

Remarks

A process may issue DosAllocSeg or DosAllocHuge to allocate shareable segments of memory. The segment may be shareable through DosGiveSeg or DosGetSeg. If the segment is shareable through DosGetSeg, then the process that allocated the memory must pass the selector of the segment to the recipient process using some means of interprocess communication.

If at the time the shared segment is allocated, it is also specified as discardable, it is automatically locked for access by the caller. The caller may free the segment for discard by a DosUnlockSeg call. A process that gains access to the discardable shared segment by calling DosGetSeg has to lock the segment with a DosLockSeg request. However, DosLockSeg may return an error, indicating the segment is already locked. In this case, the process calls DosUnlockSeg repetitively, until the segment is fully unlocked. The process then locks the segment for its own use. Locking is an attribute of the segment, not the processes using the segment.

To access named shared memory allocated with a DosAllocShrSeg request, a process issues DosGetShrSeg.

Example Code

C Binding

#define INCL_DOSMEMMGR

USHORT  rc = DosGetSeg(Selector);
SEL     Selector;      /* Selector to access */
USHORT  rc;            /* return code */

MASM Binding

EXTRN  DosGetSeg:FAR
INCL_DOSMEMMGR      EQU 1

PUSH   WORD    Selector      ;Selector to access
CALL   DosGetSeg

Returns WORD