Get Free Memory Information

Returns information about the amount of available physical memory, linear address space, and disk space for page swapping. Since DPMI clients will often run in multitasking environments, the information returned by this function should only be considered as advisory. DPMI 1.0 clients should avoid use of this function (see the last note of the call).

Call With

AX = 0500H
ES:(E)DI = selector:offset of 48-byte buffer

Returns

Carry flag = clear (this function always succeeds)
and the buffer is filled in with the following information:

Offset Length Contents

00H 4 Largest available free block in bytes

04H 4 Maximum unlocked page allocation in pages

08H 4 Maximum locked page allocation in pages

0CH 4 Linear address space size in pages

10H 4 Total number of unlocked pages

14H 4 Total number of free pages

18H 4 Total number of physical pages

1CH 4 Free linear address space in pages

20H 4 Size of paging file/partition in pages

24H 0CH Reserved, all bytes set to 0FFH

Offset	Length	Contents
00H	4	Largest available free block in bytes
04H	4	Maximum unlocked page allocation in pages
08H	4	Maximum locked page allocation in pages
0CH	4	Linear address space size in pages
10H	4	Total number of unlocked pages
14H	4	Total number of free pages
18H	4	Total number of physical pages
1CH	4	Free linear address space in pages
20H	4	Size of paging file/partition in pages
24H	0CH	Reserved, all bytes set to 0FFH

Notes

32-bit programs must use ES:EDI to point to the buffer. 16-bit programs should use ES:DI.
Only the first field of the returned structure is guaranteed to contain a valid value. Any fields that are not supported by the DPMI host will be set by the host to -1 (0FFFFFFFFH) to indicate that the information is not available.
The field at buffer offset 00H specifies the largest block of contiguous linear memory in bytes that could be allocated if the memory were to be allocated and left unlocked.
The field at buffer offset 04H specifies the largest number of pages that could be allocated (the value at offset 00H divided by the page size).
The field at buffer offset 08H specifies the largest block of memory in pages that could be allocated and then locked.
The field at buffer offset 0CH specifies the size of the total linear address space in pages. This value includes all linear address space that has already been allocated.
The field at buffer offset 10H specifies the total number of pages that are currently unlocked and could be paged out. This value also contains any free pages.
The field at buffer offset 14H specifies the number of physical pages that currently are not in use.
The field at offset 18H specifies the total number of physical pages that the DPMI host manages. This value includes all free, locked, and unlocked physical pages.
The field at offset 20H specifies the size of the DPMI host's paging partition or file in pages.
The size of the pages used by the DPMI host can be obtained with the Get Page Size function (Int 31H Function 0604H).
DPMI 1.0 clients should use Int 31H Function 050BH in preference to this function. This function is supported in DPMI 1.0 solely for backward compatibility with DPMI 0.9.