Int 2F Fn 4310  - Extended Memory Specification (xms) V2+ - Get Driver Ad  [m]

   AX = 4310h

Return: ES:BX -> driver entry point

Note:  HIMEM.SYS v2.77 chains to previous handler if AH is not 00h or 10h

See Also: AX=4300h

Perform a FAR call to the driver entry point with AH set to the function code
   AH  function
   00h  Get XMS version number

        Return: AX = XMS version (in BCD, AH=major, AL=minor)
            BX = internal revision number
            DX = 0001h if HMA (1M to 1M + 64K) exists
             0000h if HMA does not exist
   01h  Request High Memory Area (1M to 1M + 64K)
        DX = memory in bytes (for TSR or device drivers)
         FFFFh if application program

        Return: AX = 0001h success
           = 0000h failure
              BL = error code (80h,81h,90h,91h,92h) (see below)
   02h  Release High Memory Area

        Return: AX = 0001h success
           = 0000h failure
              BL = error code (80h,81h,90h,93h) (see below)
   03h  Global enable A20, for using the HMA

        Return: AX = 0001h success
           = 0000h failure
              BL = error code (80h,81h,82h) (see below)
   04h  Global disable A20

        Return: AX = 0001h success
           = 0000h failure
              BL = error code (80h,81h,82h,94h) (see below)
   05h  Local enable A20, for direct access to extended memory

        Return: AX = 0001h success
           = 0000h failure
              BL = error code (80h,81h,82h) (see below)
   06h  Local disable A20

        Return: AX = 0001h success
           = 0000h failure
              BL = error code (80h,81h,82h,94h) (see below)
   07h  Query A20 state

        Return: AX = 0001h enabled
           = 0000h disabled
            BL = error code (00h,80h,81h) (see below)
   08h  Query free extended memory, not counting HMA
        BL = 00h (some implementations leave BL unchanged on success)

        Return: AX = size of largest extended memory block in KB
            DX = total extended memory in KB
            BL = error code (00h,80h,81h,A0h) (see below)
   09h  Allocate extended memory block
        DX = Kbytes needed

        Return: AX = 0001h success
              DX = handle for memory block
           = 0000h failure
              BL = error code (80h,81h,A0h) (see below)
   0Ah  Free extended memory block
        DX = handle of block to free

        Return: AX = 0001h success
           = 0000h failure
              BL = error code (80h,81h,A2h,ABh) (see below)
   0Bh  Move extended memory block
        DS:SI -> EMM structure (see below)

        Note: if either handle is 0000h, the corresponding offset is
          considered to be an absolute segment:offset address in
          directly addressable memory

        Return: AX = 0001h success
           = 0000h failure
              BL = error code (80h-82h,A3h-A9h) (see below)
   0Ch  Lock extended memory block
        DX = handle of block to lock

        Return: AX = 0001h success
              DX:BX = 32-bit linear address of locked block
           = 0000h failure
              BL = error code (80h,81h,A2h,ACh,ADh) (see below)

        Note: MS Windows 3.x rejects this function for handles allocated
           after Windows started
   0Dh  Unlock extended memory block
        DX = handle of block to unlock

        Return: AX = 0001h success
           = 0000h failure
              BL = error code (80h,81h,A2h,AAh) (see below)
   0Eh  Get handle information
        DX = handle for which to get info

        Return: AX = 0001h success
              BH = block's lock count
              BL = number of free handles left
              DX = block size in KB
           = 0000h failure
              BL = error code (80h,81h,A2h) (see below)
        BUG: MS Windows 3.10 acts as though unallocated handles are in use

        Note: MS Windows 3.00 has problems with this call
   0Fh  Reallocate extended memory block
        DX = handle of block
        BX = new size of block in KB

        Return: AX = 0001h success
           = 0000h failure
              BL = error code (80h,81h,A0h-A2h,ABh) (see below)
   10h  Request upper memory block (nonEMS memory above 640K)
        DX = size of block in paragraphs

        Return: AX = 0001h success
              BX = segment address of UMB
              DX = actual size of block
           = 0000h failure
              BL = error code (80h,B0h,B1h) (see below)
              DX = largest available block
   11h  Release upper memory block
        DX = segment address of UMB to release

        Return: AX = 0001h success
           = 0000h failure
              BL = error code (80h,B2h) (see below)
   12h  (XMS v3.0) Reallocate upper memory block
        DX = segment address of UMB to resize
        BX = new size of block in paragraphs

        Return: AX = 0001h success
           = 0000h failure
              BL = error code (80h,B0h,B2h) (see below)
              DX = maximum available size (RM386)
   34h  (QEMM 5.11 only, undocumented) ???
   44h  (QEMM 5.11 only, undocumented) ???
   80h  (Netroom RM386 v6.00) Reallocate upper memory block
        this function is identical to function 12h
   81h  (Netroom RM386 v6.00) re-enable HMA allocation

        Return: AX = 0001h (success)
   82h  (Netroom RM386 v6.00) Cloaking API
        DX = XMS handle of block containing protected-mode code
        CL = code size (00h 16-bit, else 32-bit)
        ESI, EDI = parameters to pass to protected-mode code

        Return: AX = status
            0001h success
            0000h failed
                BL = error code (A2h,B0h) (see below)

        Note: this calls offset 0 in the XMS memory block with
       EBX = physical address of block's start
       CS = code selector for XMS block at EBX (16-bit or 32-bit)
       DS = data selector for XMS block, starting at EBX
       ES = selector for V86 memory access to full real-mode 1088K
       GS = selector for full flat address space
       ESI, EDI from V86 mode
   83h  (Netroom RM386 v6.00) Create new UMB entry
        BX = segment of high-memory block
        DX = first page of start of block
        CX = number of consecutive pages in block
        DI = start of UMB in block

        Return: AX = 0001h (success)
            DI = segment of first high-DOS block

        Note: the new UMB is not linked into the high-memory chain
   84h  (Netroom RM386 v6.00) Get all XMS handles info
        CX = size of buffer for handle info
        ES:DI -> buffer for handle info (see below)

        Return: AX = 0001h (success)
            DX = current number of allocated XMS handles
   88h  (XMS v3.0) Query free extended memory

        Return: EAX = largest block of extended memory, in KB
            BL = status
            00h success
            80h not implemented (i.e. on a 286 system)
            81h VDISK detected
            A0h all extended memory allocated
            ECX = physical address of highest byte of memory
               (valid even on error codes 81h and A0h)
            EDX = total Kbytes of extended memory (0 if status A0h)
   89h  (XMS v3.0) Allocate any extended memory
        EDX = Kbytes needed

        Return: AX = 0001h success
               DX = handle for allocated block (free with AH=0Ah)
           = 0000h failure
               BL = status (80h,81h,A0h,A1h,A2h) (see below)
   8Eh  (XMS v3.0) Get extended EMB handle information
        DX = handle

        Return: AX = 0001h success
               BH = block's lock count
               CX = number of free handles left
               EDX = block size in KB
           = 0000h failure
               BL = status (80h,81h,A2h) (see below)
        BUG: DOS 6.0 HIMEM.SYS leaves CX unchanged
   8Fh  (XMS v3.0) Reallocate any extended memory block
        DX = unlocked handle
        EBX = new size in KB

        Return: AX = 0001h success
           = 0000h failure
               BL = status (80h,81h,A0h-A2h,ABh) (see below)

Notes: HIMEM.SYS requires at least 256 bytes free stack space
   the XMS driver need not implement functions 10h through 12h to be
     considered compliant with the standard
BUG:   HIMEM v3.03-3.07 crash on an 80286 machine if any of the 8Xh functions
     are called

Error codes returned in BL:
 00h   successful
 80h   function not implemented
 81h   Vdisk was detected
 82h   an A20 error occurred
 8Eh   a general driver error
 8Fh   unrecoverable driver error
 90h   HMA does not exist
 91h   HMA is already in use
 92h   DX is less than the /HMAMIN= parameter
 93h   HMA is not allocated
 94h   A20 line still enabled
 A0h   all extended memory is allocated
 A1h   all available extended memory handles are allocated
 A2h   invalid handle
 A3h   source handle is invalid
 A4h   source offset is invalid
 A5h   destination handle is invalid
 A6h   destination offset is invalid
 A7h   length is invalid
 A8h   move has an invalid overlap
 A9h   parity error occurred
 AAh   block is not locked
 ABh   block is locked
 ACh   block lock count overflowed
 ADh   lock failed
 B0h   only a smaller UMB is available
 B1h   no UMB's are available
 B2h   UMB segment number is invalid

Format of EMM structure:
Offset Size    Description
 00h   DWORD   number of bytes to move (must be even)
 04h   WORD    source handle
 06h   DWORD   offset into source block
 0Ah   WORD    destination handle
 0Ch   DWORD   offset into destination block

Notes: if source and destination overlap, only forward moves (source base
     less than destination base) are guaranteed to work properly
   if either handle is zero, the corresponding offset is interpreted
     as a real-mode address referring to memory directly addressable
     by the processor

Format of XMS handle info [array]:
Offset Size    Description
 00h   BYTE    handle
 01h   BYTE    lock count
 02h   DWORD   handle size
 06h   DWORD   handle physical address (only valid if lock count nonzero)