DosFreeSeg

This call deallocates a memory segment.

Syntax

DosFreeSeg (Selector)

Parameters

Selector (SEL) - input : Selector of the segment to be freed.

Return Code

rc (USHORT) - return

Return code descriptions are:

0 NO_ERROR

5 ERROR_ACCESS_DENIED

212 ERROR_LOCKED

Remarks

DosFreeSeg frees selectors to segments returned by allocation calls to DosAllocSeg, DosAllocShrSeg, and DosAllocHuge. In addition, DosFreeSeg frees a selector returned by a call to DosCreateCSAlias. If a CS alias selector has been created for a data segment by a call to DosCreateCSAlias, the CS alias selector is still valid after the segment's data selector has been freed.

When allocated memory is shared, all selectors to the shared memory must be freed before the memory is deallocated. For example, if memory allocated by DosAllocSeg or DosAllocHuge has been given to another process with DosGiveSeg, the giver usually frees its selector by a call to DosFreeSeg. The recipient, in turn, frees the selector passed to it, after it has accessed the shared memory with DosGetSeg.

DosFreeSeg decrements the reference count for named shared segments allocated by DosAllocShrSeg. Access to the segment with DosGetShrSeg increments this count. When the count is 0, the memory is deallocated.

Family API Considerations

Some options operate differently in the DOS mode than in OS/2 mode. Therefore, the following restriction applies to DosFreeSeg when coding for the DOS mode:

If DosFreeSeg is issued on a CSAliased segment it deallocates the associated memory. This is inconsistent with the OS/2 mode, because DosFreeSeg must be performed on both the original and CSAliased selectors.

Example Code

C Binding

#define INCL_DOSMEMMGR
USHORT rc = DosFreeSeg(Selector);
SEL Selector; /* Selector */
USHORT rc; /* return code */

This example allocates a segment of 30,250 bytes and then discards the segment.

#define INCL_DOSMEMMGR
#define NUMBER_OF_BYTES 30250
#define ALLOC_FLAG SEG_GETTABLE
SEL Selector;
USHORT rc;
rc = DosAllocSeg(NUMBER_OF_BYTES, /* # of bytes requested */
&Selector, /* Selector allocated */
ALLOC_FLAG); /* Allocation flags */
rc = DosFreeSeg(Selector); /* Segment selector */

MASM Binding

EXTRN DosFreeSeg:FAR
INCL_DOSMEMMGR EQU 1
PUSH WORD Selector ;Selector
CALL DosFreeSeg

Returns WORD

Note

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

Family API
DOS	Process Manager	DosBeep DosExit DosSleep DosExecPgm
File Manager	DosChDir DosChgFilePtr DosClose DosDelete DosDupHandle DosMkDir DosMove DosQCurDir DosQCurDisk DosSetFileMode DosOpen DosQFileInfo DosRead DosQFileMode DosQFSInfo DosQVerify DosRmDir DosSelectDisk DosFindClose DosFindFirst DosFindNext DosSetFileInfo DosSetVerify DosWrite DosFileLocks DosSetFHandState DosNewSize DosBufReset DosQFHandState DosSetFSinfo DosShutdown
Memory Manager	DosFreeSeg DosSubAlloc DosSubFree DosSubSet DosAllocHuge DosAllocSeg DosReallocHuge DosReallocSeg DosGetHugeShift DosCreateCSAlias
NLS	DosCaseMap DosGetCtryInfo DosGetDBCSEv DosSetCtryCode DosGetCollate DosGetMessage DosInsMessage DosPutMessage
Date and Time	DosSetDateTime DosGetDateTime
Devices	DosDevConfig DosDevIOCtl DosDevIOCtl2
Signals	DosHoldSignal DosSetSigHandler
Misc	BadDynLink DosGetEnv DosGetMachineMode DosGetVersion DosError DosErrClass DosSetVec
KBD	KbdCharIn KbdFlushBuffer KbdGetStatus KbdSetStatus KbdStringIn KbdPeek
VIO	VioGetBuf VioGetConfig VioGetCurPos VioGetCurType VioGetPhysBuf VioReadCellStr VioReadCharStr VioScrollUp VioScrollDn VioScrollLf VioScrollRt VioScrUnLock VioSetCurPos VioSetCurType VioSetMode VioGetMode VioShowBuf VioWrtCellStr VioWrtCharStr VioWrtCharStrAtt VioWrtNAttr VioWrtNCell VioWrtNChar VioWrtTTY VioScrLock VioPopUp
Tools	BIND
Modules	DOSCALLS.DLL VIOCALLS.DLL KBDCALLS.DLL MSG.DLL
Libraries	API.LIB OS2386.LIB FAPI.LIB DOSCALLS.LIB SUBCALLS.LIB