Function RTReserveVirtualAddress

Function RTReserveVirtualAddress allocates a virtual address range:

int RTReserveVirtualAddress(void ** Virtual, unsigned Bytes, unsigned Flags);

Parameters

Virtual

A pointer to a pointer containing the address of the virtual address space.

*Virtual should be initialized by the application before RTReserveVirtualAddress is called to supply a preferred virtual address. If this address is available, it will be used. Otherwise, if RT_MAP_NO_RELOCATE is not set, RTReserveVirtualAddress scans the virtual address space starting at zero for a free area large enough to satisfy the request. If the original value of *Virtual is not page-aligned, the page offset of *Virtual is always preserved.

When this function succeeds, *Virtual contains the address of the reserved address range.

Bytes

Specifies the size in bytes of the required address range.

Flags

Specifies options. The only flag currently defined is RT_MAP_NO_RELOCATE. It prevents RTReserveVirtualAddress from allocating a different address to *Virtual.

return value

Can be one of the following:

Value	Meaning
RT_MAP_SUCCESS	The function succeeded.
RT_MAP_NO_PAGING	Paging is not enabled. This function requires paging.
RT_MAP_VADDR_NOT_AVAIL	The requested virtual address is not free and RT_MAP_NO_RELOCATE was specified, preventing RTReserveVirtualAddress from searching for a different address.
RT_MAP_OUT_OF_MEM	The function was unable to allocate memory for a larger page table.