DosSubAlloc: Difference between revisions
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This call suballocates portions of a segment allocated by DosAllocSeg or DosAllocShrSeg, and initialized by [[DosSubSet]]. | |||
This call suballocates portions of a segment allocated by DosAllocSeg or DosAllocShrSeg, and initialized by DosSubSet. | |||
==Syntax== | ==Syntax== | ||
DosSubAlloc (SegSelector, BlockOffset, Size) | |||
DosSubAlloc | |||
==Parameters== | ==Parameters== | ||
; SegSelector (SEL) - input : Data segment selector that allocates the memory. | ;SegSelector (SEL) - input : Data segment selector that allocates the memory. | ||
;BlockOffset (PUSHORT) - output : Address of the allocated block offset. | |||
; BlockOffset (PUSHORT) - output : Address of the allocated block offset. | ;Size (USHORT) - input : Memory block size requested in bytes. | ||
; Size (USHORT) - input : Memory block size requested in bytes. | |||
==Return Code== | ==Return Code== | ||
;rc (USHORT) - return:Return code descriptions are: | |||
* 0 NO_ERROR | |||
Return code descriptions are: | *311 ERROR_DOSSUB_NOMEM | ||
*313 ERROR_DOSSUB_BADSIZE | |||
* 0 | |||
* 311 | |||
* 313 | |||
==Remarks== | ==Remarks== | ||
Before a segment allocated by DosAllocSeg or DosAllocShrSeg can be suballocated, it must first be initialized for suballocation by a call to DosSubSet. | Before a segment allocated by [[DosAllocSeg]] or [[DosAllocShrSeg]] can be suballocated, it must first be initialized for suballocation by a call to [[DosSubSet]]. | ||
Allocation size must be a multiple of four bytes. Otherwise, it is rounded up to a multiple of four bytes. The maximum value for the size parameter is the size that was set with DosSubSet minus 8. Note that no paragraph (16-byte) alignment is required; all requests are serviced on a byte alignment basis. | Allocation size must be a multiple of four bytes. Otherwise, it is rounded up to a multiple of four bytes. The maximum value for the size parameter is the size that was set with DosSubSet minus 8. Note that no paragraph (16-byte) alignment is required; all requests are serviced on a byte alignment basis. | ||
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A suballocated block of memory in a suballocated segment is freed by a call to DosSubFree. | A suballocated block of memory in a suballocated segment is freed by a call to DosSubFree. | ||
== | ==Binding== | ||
===C | ===C=== | ||
<PRE> | <PRE> | ||
#define INCL_DOSMEMMGR | #define INCL_DOSMEMMGR | ||
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USHORT rc = DosSubAlloc(SegSelector, BlockOffset, Size); | USHORT rc = DosSubAlloc(SegSelector, BlockOffset, Size); | ||
SEL | SEL SegSelector; /* Segment selector */ | ||
PUSHORT | PUSHORT BlockOffset; /* Block Offset (returned) */ | ||
USHORT | USHORT Size; /* Size of requested block */ | ||
USHORT | USHORT rc; /* return code */ | ||
</PRE> | </PRE> | ||
===MASM | ===MASM=== | ||
<PRE> | <PRE> | ||
EXTRN DosSubAlloc:FAR | EXTRN DosSubAlloc:FAR | ||
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Returns WORD | Returns WORD | ||
</PRE> | </PRE> | ||
[[Category: | [[Category:Dos16]] | ||
Latest revision as of 08:08, 26 January 2020
This call suballocates portions of a segment allocated by DosAllocSeg or DosAllocShrSeg, and initialized by DosSubSet.
Syntax
DosSubAlloc (SegSelector, BlockOffset, Size)
Parameters
- SegSelector (SEL) - input
- Data segment selector that allocates the memory.
- BlockOffset (PUSHORT) - output
- Address of the allocated block offset.
- Size (USHORT) - input
- Memory block size requested in bytes.
Return Code
- rc (USHORT) - return
- Return code descriptions are:
- 0 NO_ERROR
- 311 ERROR_DOSSUB_NOMEM
- 313 ERROR_DOSSUB_BADSIZE
Remarks
Before a segment allocated by DosAllocSeg or DosAllocShrSeg can be suballocated, it must first be initialized for suballocation by a call to DosSubSet.
Allocation size must be a multiple of four bytes. Otherwise, it is rounded up to a multiple of four bytes. The maximum value for the size parameter is the size that was set with DosSubSet minus 8. Note that no paragraph (16-byte) alignment is required; all requests are serviced on a byte alignment basis.
A suballocated block of memory in a suballocated segment is freed by a call to DosSubFree.
Binding
C
#define INCL_DOSMEMMGR USHORT rc = DosSubAlloc(SegSelector, BlockOffset, Size); SEL SegSelector; /* Segment selector */ PUSHORT BlockOffset; /* Block Offset (returned) */ USHORT Size; /* Size of requested block */ USHORT rc; /* return code */
MASM
EXTRN DosSubAlloc:FAR INCL_DOSMEMMGR EQU 1 PUSH WORD SegSelector ;Segment selector PUSH@ WORD BlockOffset ;Block Offset (returned) PUSH WORD Size ;Size of requested block CALL DosSubAlloc Returns WORD