DosUnlockSeg: Difference between revisions
Created page with "==Description== This call unlocks a discardable segment. ==Syntax== <PRE> DosUnlockSeg (Selector) </PRE> ==Parameters== ; Selector (SEL) - input : Segment selector to ..." |
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This call unlocks a discardable segment. | This call unlocks a discardable segment. | ||
==Syntax== | ==Syntax== | ||
DosUnlockSeg (Selector) | |||
DosUnlockSeg | |||
==Parameters== | ==Parameters== | ||
; | ;Selector (SEL) - input : Segment selector to be unlocked. | ||
==Return Code== | ==Return Code== | ||
;rc (USHORT) - return: Return code descriptions are: | |||
* 0 NO_ERROR | |||
Return code descriptions are: | * 5 ERROR_ACCESS_DENIED | ||
*158 ERROR_NOT_LOCKED | |||
* 0 | |||
* 5 | |||
* 158 | |||
==Remarks== | ==Remarks== | ||
DosUnlockSeg is called to free memory for possible discard by the system in a low memory situation. The memory being freed is originally allocated by a call to DosAllocSeg or DosAllocHuge with AllocFlags bit 2 set. This memory may have been reallocated by a call to DosReallocSeg or DosReallocHuge after discard by the system. | DosUnlockSeg is called to free memory for possible discard by the system in a low memory situation. The memory being freed is originally allocated by a call to [[DosAllocSeg]] or [[DosAllocHuge]] with AllocFlags bit 2 set. This memory may have been reallocated by a call to [[DosReallocSeg]] or [[DosReallocHuge]] after discard by the system. | ||
Allocation and reallocation calls for discardable memory automatically lock the memory for access by the calling process. Thus, to access the segment, the caller does not have to lock the segment with DosLockSeg. Once a discardable segment is unlocked by a DosUnlockSeg request, access to the segment is gained by a successful DosLockSeg request. | Allocation and reallocation calls for discardable memory automatically lock the memory for access by the calling process. Thus, to access the segment, the caller does not have to lock the segment with [[DosLockSeg]]. Once a discardable segment is unlocked by a DosUnlockSeg request, access to the segment is gained by a successful DosLockSeg request. | ||
DosUnlockSeg may also be used on segments that are non-discardable, in which case it has no effect. | DosUnlockSeg may also be used on segments that are non-discardable, in which case it has no effect. | ||
== | ==Bindings== | ||
=== C | ===C=== | ||
<PRE> | <PRE> | ||
#define INCL_DOSMEMMGR | #define INCL_DOSMEMMGR | ||
| Line 34: | Line 27: | ||
USHORT rc = DosUnlockSeg(Selector); | USHORT rc = DosUnlockSeg(Selector); | ||
SEL | SEL Selector; /* Selector to unlock */ | ||
USHORT | USHORT rc; /* return code */ | ||
</PRE> | </PRE> | ||
===MASM | ===MASM=== | ||
<PRE> | <PRE> | ||
EXTRN DosUnlockSeg:FAR | EXTRN DosUnlockSeg:FAR | ||
| Line 48: | Line 41: | ||
Returns WORD | Returns WORD | ||
</PRE> | </PRE> | ||
[[Category: | [[Category:Dos16]] | ||
Latest revision as of 02:36, 26 January 2020
This call unlocks a discardable segment.
Syntax
DosUnlockSeg (Selector)
Parameters
- Selector (SEL) - input
- Segment selector to be unlocked.
Return Code
- rc (USHORT) - return
- Return code descriptions are:
- 0 NO_ERROR
- 5 ERROR_ACCESS_DENIED
- 158 ERROR_NOT_LOCKED
Remarks
DosUnlockSeg is called to free memory for possible discard by the system in a low memory situation. The memory being freed is originally allocated by a call to DosAllocSeg or DosAllocHuge with AllocFlags bit 2 set. This memory may have been reallocated by a call to DosReallocSeg or DosReallocHuge after discard by the system.
Allocation and reallocation calls for discardable memory automatically lock the memory for access by the calling process. Thus, to access the segment, the caller does not have to lock the segment with DosLockSeg. Once a discardable segment is unlocked by a DosUnlockSeg request, access to the segment is gained by a successful DosLockSeg request.
DosUnlockSeg may also be used on segments that are non-discardable, in which case it has no effect.
Bindings
C
#define INCL_DOSMEMMGR USHORT rc = DosUnlockSeg(Selector); SEL Selector; /* Selector to unlock */ USHORT rc; /* return code */
MASM
EXTRN DosUnlockSeg:FAR INCL_DOSMEMMGR EQU 1 PUSH WORD Selector ;Selector to unlock CALL DosUnlockSeg Returns WORD