DosAllocMem - Parameters

ppb (PPVOID) - output

A pointer to a variable that will receive the base address of the allocated private memory object.

cb (ULONG) - input

Size, in bytes, of the private memory object to allocate.

The size is rounded up to the next page-size boundary. The size of a page is 4KB.

flag (ULONG) - input

Allocate attribute and desired access protection flags.

A set of flags describing the allocation attributes and desired access protection for the private memory object. Possible values are shown in the lists below:

Allocation Attributes

PAG_COMMIT (0x00000010)

All pages in the private memory object are initially committed.
OBJ_TILE (0x00000040)
The private memory object must be allocated in the first 512MB of virtual-address space, with 16-bit selectors mapping the memory object.
The 16-bit selectors are allocated to map the 32-bit object at 64KB boundaries. The figure below shows how the 16-bit alias selectors map the 32-bit object.

    32-bit             32-bit               16-bit alias
    Offset             Object               Selectors

   BaseAddress+000KB┌──────────────┐ ───── Sel
                    │              │
   BaseAddress+064KB├──────────────┤ ───── Sel+HugeInc
                    │              │
   BaseAddress+128KB├──────────────┤ ───── Sel+HugeInc*2
                    │              │
   BaseAddress+192KB├──────────────┤ ───── Sel+HugeInc*3
                    │              │

HugeInc is the huge increment used for DosAllocHuge.

Desired Access Protection

PAG_EXECUTE (0x00000004)

Execute access to the committed pages in the private memory object
PAG_READ (0x00000001)
Read access
PAG_WRITE (0x00000002)
Write access
PAG_GUARD (0x00000008)
Access to the committed pages in the private memory object causes a "guard page entered" condition to be raised in the subject process.
At least one of the bits PAG_READ, PAG_WRITE, or PAG_EXECUTE must be set.

ulrc (APIRET) - returns

Return Code.

DosAllocMem returns one of the following values:

• NO_ERROR 8
  ERROR_NOT_ENOUGH_MEMORY
  87
  ERROR_INVALID_PARAMETER
  95
  ERROR_INTERRUPT
  For a full list of error codes, see Errors.

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