Resize Linear Memory Block

Call With

AX = 0505H
ESI = memory block handle
ECX = new block size (bytes, must be nonzero)
EDX = flags

Bit	Significance
0	0 = create uncommitted pages
	1 = create committed pages
1	0 = do not update segment descriptors
	1 = segment descriptor update required
2-31	reserved, must be zero

Returns

if function successful
Carry flag = clear
EBX = new linear base address of memory block
ESI = new handle for memory block

if function unsuccessful
Carry flag = set
AX = error code

8001H	unsupported function (16-bit host)
8012H	linear memory unavailable
8013H	physical memory unavailable
8014H	backing store unavailable
8016H	handle unavailable
8021H	invalid value (ECX=0)
8023H	invalid handle (in ESI)

Notes

• A DPMI 1.0 host that is 16-bit only will not support this function.

• A 16-bit client of a 32-bit DPMI 1.0 host can use this function.

• After this function returns, the previous handle for the memory block is invalid and should not be used.

• If this function fails, the block's size and base address are always unmodified.

• If the size of the block is increased, the new pages are committed or uncommitted according to the value of bit 0 of EDX, and the block's linear base address may change. If the size of the block is decreased, pages at the end of the block are freed, and the block's base address is always unchanged.

• If the block's linear base address is changed by this function, and the function was called with bit 1 of EDX set (1), the DPMI host updates the descriptors f or each of the segments in the update list which fall within the memory block. Descriptors for segments which do not fall within the memory block are not modified. Expand-up segments fall within the memory block if the segment base is within the block. Expand-down segments fall within the memory block if the (segment base + the limit - 1) is within the block. In either case, the segment base is modified by the distance the block moves, and the segment limit is not changed. The moving of the memory block and the updating of descriptors is performed atomically; i.e. the host will not deliver any hardware interrupts to the client during the update.

• Int 31H Function 0503H, which also resizes linear memory blocks, does not necessarily page-align blocks and cannot create uncommitted pages or update descriptors.