[ Home |
Alpha index |
Topic index |
The OS/2 API Project
[ Syntax |
rc = DosAllocMem( pBaseAddress,
- PPVOID pBaseAddress (output)
- This is a pointer to the variable which will recieve the base address of the allocated
private memory object.
- ULONG ulObjectSize (input)
- The size in bytes of the memory block you want to allocate. This will, by the system,
be rounded up to the next page-size boundary.
- ULONG ulAllocationFlags (input)
- Flags used to describe allocation attributes, as well as access protection of the
private memory block.
- Setting PAG_COMMIT (0x00000010) makes all private memory blocks initially
- Setting OBJ_TILE (0x00000040) forces the memory block to be allocated in the
first 512MB of virtual-address space. Mapping the memory block is done with the 16-bit
selectors. The following table shows how a 32-bit memory block is mapped using 16-bit
+ HugeInc * 2|
|. . .||. . .|
- HugeInc is the same huge increment that is used by DosAllocHuge.
- Setting PAG_EXECUTE (0x00000004) tells the system that 'execute access' to the
commited pages is desired in the memory block.
- Setting PAG_READ (0x00000001) tells the system that 'read access' is desired.
- Setting PAG_WRITE (0x00000002) tells the system that 'write access' is desired.
- Setting PAG_GUARD (0x00000008) tells the system that an access to the committed
pages should cause a guard page exception to be raised.
- At least one of PAG_EXECUTE,PAG_WRITE or PAG_READ must be set.
- APIRET rc
- The following values can be returned
DosAllocMem is used to allocate a private memory object, within the boundaries of the
#include /* This will get the memory managment flags */
PVOID BaseAddress; /* Pointer to the allocated memory block */
ULONG ObjectSize; /* The requested size of the memory block */
ULONG AllocationFlags; /* Flags */
APIRET rc; /* Will recieve the return code */
ObjectSize = 9000; /* Asking for 9000 bytes, this will */
/* rounded up to 12KB. */
AllocationFlags = PAG_WRITE | PAG_EXECUTE;
/* Allows read/write to the memory block, but */
/* the block isn't committed within memory */
/* yet. */
rc = DosAllocMem(&BaseAddress, ObjectSize, AllocationFlags);
if ( rc != 0)
/* We have an error we must take care of. */
Stefan Mars -
Last modified March 16/1996
Please send all errors, comments, and suggestions to:
The OS/2 API Project