Resize DOS Memory Block

Call With

AX = 0102H
BX = new block size in (16-byte) paragraphs
DX = selector of block to modify

Returns

if function successful
Carry flag = clear

if function unsuccessful
Carry flag = set
AX = error code

0007H	memory control blocks damaged (also returned by DPMI 0.9 hosts).
0008H	insufficient memory (also returned by DPMI 0.9 hosts).
0009H	incorrect memory segment specified (also returned by DPMI 0.9 hosts).
8011H	descriptor unavailable
8022H	invalid selector

BX = maximum possible block size (paragraphs)

Notes

• Requests to increase the size of an existing DOS memory block may fail due to subsequent DOS memory block allocations causing fragmentation of DOS memory, or insufficient remaining DOS memory. In addition, the function will fail if the block is growing past a 64 KB boundary and the next descriptor in the LDT is not available.

• A request to decrease the size of a DOS memory block may cause some descriptors that were previously allocated to the block to be freed and the limit of the new last descriptor for the block to be changed.

• Under a DPMI 1.0 host, any segment registers which contain a selector being modified are reloaded by this function and any segment registers which contain a selector being freed are zeroed by this function.

• Client programs should never modify or free any descriptors allocated by this function. The Free DOS Memory Block function (Int 31H Function 0101H) will deallocate the descriptors automatically.

• Refer to the rules for descriptor usage in Appendix D.