DosGetHugeShift: Difference between revisions
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This call returns a shift count used to derive the selectors that address memory allocated with [[DosAllocHuge]]. | This call returns a shift count used to derive the selectors that address memory allocated with [[DosAllocHuge]]. | ||
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==Return Code== | ==Return Code== | ||
;rc (USHORT) - return:Return code description is: | |||
Return code description is: | *0 NO_ERROR | ||
* 0 | |||
==Remarks== | ==Remarks== | ||
Each segment of a huge memory allocation has a unique selector. To compute the next sequential selector in a huge memory area, take the value 1, shift it left by the number of bits specified in shift count. Use the resulting value as an increment to add to the previous selector (using the selector returned by DosAllocHuge as the first selector). For example: | Each segment of a huge memory allocation has a unique selector. To compute the next sequential selector in a huge memory area, take the value 1, shift it left by the number of bits specified in shift count. Use the resulting value as an increment to add to the previous selector (using the selector returned by DosAllocHuge as the first selector). For example: | ||
* Assume DosAllocHuge is issued with NumSeg equal to 3, and that the number 63 is returned for the selector of the first segment. | * Assume DosAllocHuge is issued with NumSeg equal to 3, and that the number 63 is returned for the selector of the first segment. | ||
* If DosGetHugeShift returns a shift count of 4, shifting the value "1" by this amount results in an increment of 16. | * If DosGetHugeShift returns a shift count of 4, shifting the value "1" by this amount results in an increment of 16. | ||
* Adding this increment to selector number 63 produces 79 for the second selector. Adding the same increment to selector number 79 yields 95 for the third selector. | * Adding this increment to selector number 63 produces 79 for the second selector. Adding the same increment to selector number 79 yields 95 for the third selector. | ||
== | ==Bindings== | ||
===C | ===C=== | ||
<PRE> | <PRE> | ||
#define INCL_DOSMEMMGR | #define INCL_DOSMEMMGR | ||
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USHORT rc = DosGetHugeShift(ShiftCount); | USHORT rc = DosGetHugeShift(ShiftCount); | ||
PUSHORT | PUSHORT ShiftCount; /* Shift Count (returned) */ | ||
USHORT rc; /* return code */ | |||
USHORT | |||
</PRE> | </PRE> | ||
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Returns WORD | Returns WORD | ||
</PRE> | </PRE> | ||
[[Category:Dos]] | [[Category:Dos]] | ||
Revision as of 17:56, 29 November 2019
This call returns a shift count used to derive the selectors that address memory allocated with DosAllocHuge.
Syntax
DosGetHugeShift (ShiftCount)
Parameters
- ShiftCount (PUSHORT) - output
- Address of the shift count.
Return Code
- rc (USHORT) - return
- Return code description is:
- 0 NO_ERROR
Remarks
Each segment of a huge memory allocation has a unique selector. To compute the next sequential selector in a huge memory area, take the value 1, shift it left by the number of bits specified in shift count. Use the resulting value as an increment to add to the previous selector (using the selector returned by DosAllocHuge as the first selector). For example:
- Assume DosAllocHuge is issued with NumSeg equal to 3, and that the number 63 is returned for the selector of the first segment.
- If DosGetHugeShift returns a shift count of 4, shifting the value "1" by this amount results in an increment of 16.
- Adding this increment to selector number 63 produces 79 for the second selector. Adding the same increment to selector number 79 yields 95 for the third selector.
Bindings
C
#define INCL_DOSMEMMGR USHORT rc = DosGetHugeShift(ShiftCount); PUSHORT ShiftCount; /* Shift Count (returned) */ USHORT rc; /* return code */
MASM Binding
EXTRN DosGetHugeShift:FAR INCL_DOSMEMMGR EQU 1 PUSH@ WORD ShiftCount ;Shift Count (returned) CALL DosGetHugeShift Returns WORD