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Pascal/Delphi Source File | 1992-07-05 | 44.1 KB | 927 lines

{-------------------------------------------------------------------------- UNIT : XMM INITIAL : 19891127 v 1.00 AUTHOR : Jeroen W. Pluimers UPDATE : 19920705 v 1.20 DESCRIPTION : eXpanded Memory Manager HISTORY : 19891127 - 1.00 - jwp initial translation from XMS 2.0 specification 19909322 - 1.11 - jwp final XMS 2.0 implementation 19920705 - 1.20 - jwp incorporation of XMS 3.0 specification COMPUTER : NEAT-AT, ERC 386/25 COMPILER : TURBO PASCAL 5.0, 5.5 and 6.0 COPYRIGHT : (c) 1989-1992 Pluimers Software Ontwikkeling. --------------------------------------------------------------------------} Unit XMM; {$I Directive.Inc } Interface Type XMMMoveRec = Record Case Boolean of False : (Length : Longint; { 32-bit number of bytes to transfer } SourceHandle : Word; { Handle of source block } SourceOffset : Longint; { 32-bit offset into source } DestHandle : Word; { Handle of destination block } DestOffset : Longint; { 32-bit offset into destination block } ); True : (TheLenght : Longint; { note that the lenght must be even ! } ZeroSource : Word; { zero sourcehandle means a seg:ofs } SourcePtr : Pointer; { pointer to "normal" memory } ZeroDest : Word; { zero dest handle means a seg:ofs } DestPtr : Pointer; { pointer to "normal" memory } ); End; { XMMMoveRec } Const XMMOk = $00;{ function succeeded. } XMMNotImplemented = $80;{ the function is not implemented. } XMMVDiskFound = $81;{ a VDISK device is detected. } XMMA20Err = $82;{ an A20 error occurs. } XMMGenErr = $8E;{ a general driver error occurs. } XMMUnrecovErr = $8F;{ an unrecoverable driver error occurs. } XMMHMAnotExist = $90;{ the HMA does not exist. } XMMHMAInUse = $91;{ the HMA is already in use. } XMMHMAminSize = $92;{ DX is less than the /HMAMIN= parameter. } XMMHMANotAlloced = $93;{ the HMA is not allocated. } XMMA20StillEnabled = $94;{ the A20 line is still enabled. } XMMOutOfMemory = $A0;{ all extended memory is allocated. } XMMOutOfHandles = $A1;{ all available extended memory handles are in use.} XMMInvalidHandle = $A2;{ the handle is invalid. } XMMSourceHanldeInv = $A3;{ the SourceHandle is invalid. } XMMSourceOffsetInv = $A4;{ the SourceOffset is invalid. } XMMDestHanleInv = $A5;{ the DestHandle is invalid. } XMMDestOffset = $A6;{ the DestOffset is invalid. } XMMLenInv = $A7;{ the Length is invalid. } XMMOverlap = $A8;{ the move has an invalid overlap. } XMMParity = $A9;{ a parity error occurs. } XMMEMBUnlocked = $AA;{ the block is not locked. } XMMEMBLocked = $AB;{ the block is locked. } XMMLockOverflow = $AC;{ the block's lock count overflows. } XMMLockFail = $AD;{ the lock fails. } Function XMMInstalled : Boolean; {--------------------------------------------------------------------------- ROUTINE : XMMInstalled DESCRIPTION : THIS ROUTINE MUST BE CALLED BEFORE ANY OTHER ROUTINE OR ALL THE OTHER ROUTINES WILL FAIL WITH ERROR CODE $80. RETURNS : False - No XMM driver found. True - An XMM driver has been found. POST : Internal pointer to XMM driver is established. ---------------------------------------------------------------------------} Function XMMVersion(Var XMSversion, XMSrevision : Word; Var HMAAvailable : Boolean) : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMVersion DESCRIPTION : Get version numbers. Both the XMS version number and the driver internal revision number are encoded as follows : Low byte = minor part. High byte = major part. e.g. XMSversion $0277 would mean version 2.77. The HMAAvailable indicates the existence of the HMA (not its availability) and is intended mainly for installation programs. OUT : XMSversion - XMS version number. XMSrevision - Driver internal revision number. HMAAvailable - False - no HMA detected. True - HMA has been detected. RETURNS : XMMOk - Always if XMMInstalled has been called. XMMNotImplemented - XMMInstalled has not been called. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMRequestHMA (SpaceNeeded : Word) : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMRequestHMA DESCRIPTION : Attempts to reserve the whole 64K-16 byte high memory area for the caller. If the HMA is currently unused, the caller's size parameter is compared to the /HMAMIN= parameter on the driver's command line. If the value passed by the caller is greater than or equal to the amount specified by the driver's parameter, the request succeeds. This provides the ability to ensure that programs which use the HMA efficiently have priority over those which do not. NOTE: See the sections "Prioritizing HMA Usage" and "High Memory Area Restrictions" in the documentation for more information. IN : SpaceNeeded - Number of bytes in the HMA needed by caller. It is recommended that if the caller is an application program this value is set to 65535 and if the caller is a TSR the real number of bytes is used. RETURNS : XMMOk - the HMA is assigned to the caller. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMHMANotExist - the HMA does not exist. XMMHAMInUse - the HMA is already in use. XMMHAMMinSize - SpaceNeeded is less than the /HMAMIN= environment parameter. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMReleaseHMA : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMReleaseHMA DESCRIPTION : Releases the high memory area and allows other programs to use it. Programs which allocate the HMA must release it before exiting. When the HMA has been released, any code or data stored in it becomes invalid and should not be accessed. RETURNS : XMMOk - the HMA is successfully released. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMHMANotExist - the HMA does not exist. XMMNotAllocated - the HMA was not allocated. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMGlobalEnableA20 : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMGlobalEnableA20 DESCRIPTION : Attempts to enable the A20 line. It should only be used by programs which have control of the HMA. The A20 line should be turned off via XMMGlobalDisableA20 before a program releases control of the system. NOTE: On many machines, toggling the A20 line is a relatively slow operation. RETURNS : XMMOk - the A20 line is enabled. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMA20Err - and A20 error occurs. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMGlobalDisableA20 : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMGlobalDisableA20 DESCRIPTION : Attempts to disable the A20 line. It should only be used by programs which have control of the HMA. The A20 line should be disabled before a program releases control of the system. NOTE: On many machines, toggling the A20 line is a relatively slow operation. RETURNS : XMMOk - the A20 line is disabled. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMA20Err - and A20 error occurs. XMMA20StillEnabled - the A20 line is still enabled. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMLocalEnableA20 : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMLocalEnableA20 DESCRIPTION : Attempts to enable the A20 line. It should only be used by programs which need direct access to extended memory. Programs which use this function should call XMMLocalDisableA20 before releasing control of the system. NOTE: On many machines, toggling the A20 line is a relatively slow operation. RETURNS : XMMOk - the A20 line is enabled. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMA20Err - and A20 error occurs. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMLocalDisableA20 : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMLocalDisableA20 DESCRIPTION : Cancels a previous call to XMMLocalEnableA20. It should only be used by programs which need direct access to extended memory. Previous calls to XMMLocalEnableA20 must be canceled before releasing control of the system. NOTE: On many machines, toggling the A20 line is a relatively slow operation. RETURNS : XMMOk - the A20 line is disabled. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMA20Err - and A20 error occurs. XMMA20StillEnabled - the A20 line is still enabled. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMQueryA20 (Var A20IsOn : Boolean) : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMQueryA20 DESCRIPTION : Checks to see if the A20 line is physically enabled. It does this in a hardware independent manner by seeing if "memory wrap" occurs. OUT : A20IsOn - False - the A20 line is not physically enabled. True - the A20 line us physically enabled. RETURNS : XMMOk - the function succeeds. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMQueryFree (Var LargestFree, TotalFree : Word): Byte; {--------------------------------------------------------------------------- ROUTINE : XMMQueryFree DESCRIPTION : Returns the size of the largest available extended memory block and total free memory in the system. NOTE: The 64K HMA is not included in the returned value even if it is not in use. OUT : LargestFree - Size of the largest free extended memory block in K-bytes. TotalFree - Total amount of free extended memory in K-bytes. RETURNS : XMMOk - the function succeeds. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMOutOfMemory - all available extended memory is allocated. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMAllocateEMB ( BlockSize : Word; Var Handle : Word) : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMAllocateEMB DESCRIPTION : Attempts to allocate a block of the given size out of the pool of free extended memory. If a block is available, it is reserved for the caller and a 16-bit handle to that block is returned. The handle should be used in all subsequent extended memory calls. If no memory was allocated, the returned handle is null. NOTE: Extended memory handles are scarce resources. Programs should try to allocate as few as possible at any one time. When all of a driver's handles are in use, any free extended memory is unavailable. IN : BlockSize - Amount of extended memory being requested in K-bytes. OUT : Handle - 16-bit handle to the allocated block. RETURNS : XMMOk - the block is allocated. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMOutOfMemory - all available extended memory is allocated. XMMOutOfHandles - all available extended memory handles are in use. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMFreeEMB (Handle : Word) : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMFreeEMB DESCRIPTION : This function frees a block of extended memory which was previously allocated using XMMAllocateEMB. Programs which allocate extended memory should free their memory blocks before exiting. When an extended memory buffer is freed, its handle and all data stored in it become invalid and should not be accessed. IN : Handle - 16-bit handle to the allocated block which should be freed. RETURNS : XMMOk - the block is allocated. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMInvalidHandle - the handle is invalid. XMMEMBLocked - the block is locked. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMMoveEMB (MoveRec : XMMMoveRec) : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMMoveEMB DESCRIPTION : This function attempts to transfer a block of data from one location to another. It is primarily intended for moving blocks of data between conventional memory and extended memory, however it can be used for moving blocks within conventional memory and within extended memory. NOTE: If SourceHandle is set to 0000h, the SourceOffset is interpreted as a standard segment:offset pair which refers to memory that is directly accessible by the processor. The segment:offset pair is stored in Intel DWORD notation. The same is true for DestHandle and DestOffset. SourceHandle and DestHandle do not have to refer to locked memory blocks. Length must be even. Although not required, WORD-aligned moves can be significantly faster on most machines. DWORD aligned move can be even faster on 80386 machines. If the source and destination blocks overlap, only forward moves (i.e. where the source base is greater ???? than the destination base) are guaranteed to work properly. Programs should not enable the A20 line before calling this function. The state of the A20 line is preserved. This function is guaranteed to provide a reasonable number of interrupt windows during long transfers. The MoveStruc is a structure of type ExtMemMoveRec which is defined as follows : ExtMemMoveRec = Record Case Boolean of False : (Length : Longint; number of bytes to transfer SourceHandle : Word; Handle of source block SourceOffset : Longint; offset into source DestHandle : Word; Handle of destination block DestOffset : Longint; offset into dest block ); True : (TheLenght : Longint; lenght must be even ! ZeroSource : Word; zero sourcehandle means a SourcePtr : Pointer; ptr to "normal" memory ZeroDest : Word; zero dest handle means a DestPtr : Pointer; ptr to "normal" memory ); End; (* ExtMemMoveRec *) IN : MoveStruc - Pointer to an Extended Memory Move Structure (see above). RETURNS : XMMOk - the move is successful. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMA20Err - an A20 error occurs. XMMSourceHanldeInv - the SourceHandle is invalid. XMMSourceOffsetInv - the SourceOffset is invalid. XMMDestHanleInv - the DestHandle is invalid. XMMDestOffset - the DestOffset is invalid. XMMLenInv - the Length is invalid. XMMOverlap - the move has an invalid overlap. XMMParity - a parity error occurs. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMLockEMB ( Handle : Word; Var Linear : Longint) : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMLockEMB DESCRIPTION : Locks an extended memory block and returns its base address as a 32-bit linear address. Locked memory blocks are guaranteed not to move. The 32-bit pointer is only valid while the block is locked because unlocked blocks may be moved by the XMS driver. Locked blocks should be unlocked as soon as possible. NOTE: A block does not have to be locked before using XMMMoveEMB. "Lock counts" are maintained for EMBs. IN : Handle - Extended memory block handle to lock. OUT : Linear - 32-bit linear address of the locked block. RETURNS : XMMOk - the block is locked. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMInvalidHandle - the handle is invalid. XMMLockOverflow - the block's lock count overflows. XMMLockFail - the lock fails. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMUnLockEMB (Handle : Word) : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMUnLockEMB DESCRIPTION : Unlocks a locked extended memory block. Any 32-bit pointers into the block become invalid and should no longer be used. IN : Handle - Extended memory block handle to unlock. RETURNS : XMMOk - the block is unlocked. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMInvalidHandle - the handle is invalid. XMMEMBUnlocked - the block is not locked. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMGetHandleInfo ( Handle : Word; Var LockCount, FreeHandles : Byte; Var BlockLength : Word) : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMGetHandleInfo DESCRIPTION : Returns additional information about an extended memory block to the caller. NOTE: To get the block's base address, use XMMLockEMB. IN : Handle - Extended memory block handle. OUT : LockCount - The block's lock count. FreeHandles - Number of free EMB handles in the system. BlockLength - The block's length in K-bytes. RETURNS : XMMOk - the block's information is found. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMInvalidHandle - the handle is invalid. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMReallocateEMB (Handle, NewSize : Word) : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMReallocateEMB DESCRIPTION : Attempts to reallocate an unlocked extended memory block so that it becomes the newly specified size. If the new size is smaller than the old block's size, all data at the upper end of the old block is lost. IN : Handle - Unlocked extended memory block handle to reallocate. NewSize - New size for the extended memory block in K-bytes. RETURNS : XMMOk - the block is reallocated. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMOutOfMemory - all available extended memory is allocated. XMMOutOfHandles - all available extended memory handles are in use. XMMInvalidHandle - the handle is invalid. XMMEMBLocked - the block is locked. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMRequestUMB ( RequestSize : Word; Var UMBSeg, BlockSize : Word) : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMRequestUMB DESCRIPTION : Attempts to allocate an upper memory block to the caller. If the function fails, the size of the largest free UMB is returned in DX. NOTE: By definition UMBs are located below the 1MB address boundary. The A20 Line does not need to be enabled before accessing an allocated UMB. This function does not need to be implemented by an XMS driver. UMBs are paragraph aligned. To determine the size of the largest available UMB, attempt to allocate one with a size of FFFFh. UMBs are unaffected by EMS calls. IN : RequestSize - Size of requested memory block in paragraphs (one paragraph is 16 bytes). OUT : UMBSeg - Segment number of the upper memory block. BlockSize - If the request is granted, actual size in paragraphs of the allocated block in paragraphs. Otherwise, size of the largest available UMB in paragraphs. RETURNS : XMMOk - the request is granted. XMMNotImplemented - the function is not implemented. XMMUMBSizeTooBig - a smaller UMB is available. XMMNoUMBs - no UMBs are available. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMReleaseUMB (UMBSeg : Word) : Byte; {--------------------------------------------------------------------------- ROUTINE : XMMReleaseUMB DESCRIPTION : This function frees a previously allocated upper memory block. When an UMB has been released, any code or data stored in it becomes invalid and should not be accessed. NOTE: This function does not need to be implemented by an XMS driver. IN : UMBSeg - Segment number of the upper memory block. RETURNS : XMMOk - the block was released. XMMNotImplemented - the function is not implemented. XMMInvalidUMB - the UMB segment number is invalid. PRE : XMMInstalled must have been called first. ---------------------------------------------------------------------------} Function XMMReallocateUMB (RequestSize : Word; UMBSeg : Word) : Byte; { --------------------------------------------------------------------------- ROUTINE : XMMReallocateUMB DESCRIPTION : This function attempts to reallocate an Upper Memory Block to a newly specified size. If the new size is smaller than the old block's size, all data at the upper end of the block is lost. NOTE: This function does not need to be implemented by an XMS driver. IN : UMBSeg - Segment number of the upper memory block. RETURNS : XMMOk - the block was released. XMMNotImplemented - the function is not implemented. XMMUMBSizeTooBig - a smaller UMB is available. XMMInvalidUMB - the UMB segment number is invalid. PRE : XMMInstalled must have been called first. --------------------------------------------------------------------------- } Function XMMQueryAnyFree (Var LargestFree, LastByte, TotalFree : LongInt): Byte; { --------------------------------------------------------------------------- ROUTINE : XMMQueryAnyFree DESCRIPTION : This function uses 32-bit values to return the size of available memory, thus allowing returns up to 4GByte. Additionally, it returns the highest known physical memory address, that is, the physical address of the last byte of memory. There may be discontinuities in the memory map below this address. The memory pool reported on is the same as that reported on by the existing Query Free Extended Memory function 08h. If the highest memory address is not more than 64 Mb, then these two functions will return the same results. Because of its reliance on 32-bit registers, this function is only available on 80386 and higher processors. XMS drivers on 80286 machines should return error code 80h if this function is called. If error code 81h is returned, the value in ECX will still be valid. If error code A0h is returned, EAX and EDX will be 0, and ECX will still be valid. OUT : LargestFree - Size of the largest free extended memory block in K-bytes. LastByte - Physical address of the last byte in memory. TotalFree - Total amount of free extended memory in K-bytes. RETURNS : XMMOk - the function succeeds. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMOutOfMemory - all available extended memory is allocated. PRE : XMMInstalled must have been called first. --------------------------------------------------------------------------- } Function XMMAllocateAnyEMB ( BlockSize : Longint; Var Handle : Word) : Byte; { --------------------------------------------------------------------------- ROUTINE : XMMAllocateAnyEMB DESCRIPTION : This function is similar to the existing Allocate Extended Memory 09h, except that it uses a 32-bit instead of a 16-bit value to specify the amount of memory requested. It allocates from the same memory and handle pool as the current function. Since it requires a 32-bit register, this function can be supported only on 80386 and higher processors, and XMS drivers on 80286 machines should return error code 80h. IN : BlockSize - Amount of extended memory being requested in K-bytes. OUT : Handle - 16-bit handle to the allocated block. RETURNS : XMMOk - the block is allocated. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMOutOfMemory - all available extended memory is allocated. XMMOutOfHandles - all available extended memory handles are in use. PRE : XMMInstalled must have been called first. --------------------------------------------------------------------------- } Function XMMGetExtendedHandleInfo ( Handle : Word; Var LockCount : Byte; Var FreeHandles : Word; Var BlockLength : Longint) : Byte; { --------------------------------------------------------------------------- ROUTINE : XMMGetExtendedHandleInfo DESCRIPTION : This function is similar to the Get EMB Handle Information function. Since it uses a 32-bit register to report the block size, it can be used to get information on blocks larger than 64 Mb. It also uses a 16-bit instead of 8-bit register to report the number of free handles, allowing the handle pool to be extended beyond 256 entries. Because of its reliance on a 32-bit register, this function is available on 80386 and higher processors. XMS drivers on 80286 machines should return error code 80h if this function is called. IN : Handle - Extended memory block handle. OUT : LockCount - The block's lock count. FreeHandles - Number of free EMB handles in the system. BlockLength - The block's length in K-bytes. RETURNS : XMMOk - the block's information is found. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMInvalidHandle - the handle is invalid. PRE : XMMInstalled must have been called first. --------------------------------------------------------------------------- } Function XMMReallocateAnyEMB (Handle, NewSize : Longint) : Byte; { --------------------------------------------------------------------------- ROUTINE : XMMReallocateAnyEMB DESCRIPTION : This function is similar to the existing Reallocate Extended Memory, except that it uses a 32-bit instead of a 16-bit value to specify the amount of memory requested. It allocates from the same memory and handle pool as the current function. Since it requires a 32-bit register, this function can be supported only on 80386 and higher processors, and XMS drivers on 80286 machines should return error code 80h. IN : Handle - Unlocked extended memory block handle to reallocate. NewSize - New size for the extended memory block in K-bytes. RETURNS : XMMOk - the block is reallocated. XMMNotImplemented - the function is not implemented. XMMVDiskFound - a VDISK device is detected. XMMOutOfMemory - all available extended memory is allocated. XMMOutOfHandles - all available extended memory handles are in use. XMMInvalidHandle - the handle is invalid. XMMEMBLocked - the block is locked. PRE : XMMInstalled must have been called first. --------------------------------------------------------------------------- } {-----------------------------------------------------------------------------} { } { Implementation } { } {-----------------------------------------------------------------------------} Implementation {$L XMM.OBJ } { Link in the assembler part } Function XMMInstalled; External; Function XMMVersion; External; Function XMMRequestHMA; External; Function XMMReleaseHMA; External; Function XMMGlobalEnableA20; External; Function XMMGlobalDisableA20; External; Function XMMLocalEnableA20; External; Function XMMLocalDisableA20; External; Function XMMQueryA20; External; Function XMMQueryFree; External; Function XMMAllocateEMB; External; Function XMMFreeEMB; External; Function XMMMoveEMB; External; Function XMMLockEMB; External; Function XMMUnLockEMB; External; Function XMMGetHandleInfo; External; Function XMMReallocateEMB; External; Function XMMRequestUMB; External; Function XMMReleaseUMB; External; Function XMMReallocateUMB; External; Function XMMQueryAnyFree; External; Function XMMAllocateAnyEMB; External; Function XMMGetExtendedHandleInfo; External; Function XMMReallocateAnyEMB; External; End. ---------------------------------------------------------------------------- Some notes about HMA usage from the official Microsoft documentation. ---------------------------------------------------------------------------- PRIORITIZING HMA USAGE: ----------------------- For DOS users to receive the maximum benefit from the High Memory Area, programs which use the HMA must store as much of their resident code in it as is possible. It is very important that developers realize that the HMA is allocated as a single unit. For example, a TSR program which grabs the HMA and puts 10K of code into it may prevent a later TSR from putting 62K into the HMA. Obviously, regular DOS programs would have more memory available to them below the 640K line if the 62K TSR was moved into the HMA instead of the 10K one. The first method for dealing with conflicts such as this is to require programs which use the HMA to provide a command line option for disabling this feature. It is crucial that TSRs which do not make full use of the HMA provide such a switch on their own command line (suggested name "/NOHMA"). The second method for optimizing HMA usage is through the /HMAMIN= parameter on the XMS device driver line. The number after the parameter is defined to be the minimum amount of HMA space (in K-bytes) used by any driver or TSR. For example, if "DEVICE=HIMEM.SYS /HMAMIN=48" is in a user's CONFIG.SYS file, only programs which request at least 48K would be allowed to allocate the HMA. This number can be adjusted either by installation programs or by the user himself. If this parameter is not specified, the default value of 0 is used causing the HMA to be allocated on a first come, first served basis. Note that this problem does not impact application programs. If the HMA is available when an application program starts, the application is free to use as much or as little of the HMA as it wants. For this reason, applications should pass FFFFh in DX when calling Function 01h. HIGH MEMORY AREA RESTRICTIONS: ------------------------------ - Far pointers to data located in the HMA cannot be passed to DOS. DOS normalizes any pointer which is passed into it. This will cause data addresses in the HMA to be invalidated. - Disk I/O directly into the HMA (via DOS, INT 13h, or otherwise) is not recommended. - Programs, especially drivers and TSRs, which use the HMA *MUST* use as much of it as possible. If a driver or TSR is unable to use at least 90% of the available HMA (typically ~58K), they must provide a command line switch for overriding HMA usage. This will allow the user to configure his machine for optimum use of the HMA. - Device drivers and TSRs cannot leave the A20 line permanently turned on. Several applications rely on 1MB memory wrap and will overwrite the HMA if the A20 line is left enabled potentially causing a system crash. - Interrupt vectors must not point into the HMA. This is a result of the previous restriction. Note that interrupt vectors can point into any allocated upper memory blocks however. The description of all functions and the notes about HMA usage are Copyright (c) 1988-1992 Microsoft Corporation. Because this XMM is public domain (as is HIMEM) I am so free to use that text and I won't accept any claims from anyone for it. Furthermore I also use the same disclaimer as in XMS.TXT on the HIMEM distribution disk : Disclaimer of Warranty: ----------------------- I, JEROEN W. PLUIMERS, FURTHER CALLED "THE AUTHOR" AND MY COMPANY EXCLUDE ANY AND ALL IMPLIED WARRANTIES, INCLUDING WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. NEITHER THE AUTHOR NOR HIS COMPANY MAKE ANY WARRANTY OF REPRESENTATION, EITHER EXPRESS OR IMPLIED, WITH RESPECT TO THIS EXTENDED MEMORY MANAGER, ITS QUALITY, PERFORMANCE, MERCHANTABILITY, OR FITNESS FOR A PARTICULAR PURPOSE. NEITHER THE AUTHOR NOR HIS COMPANY SHALL HAVE ANY LIABILITY FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF OR RESULTING FROM THE USE OR MODIFICATION OF THIS EXTENDED MEMORY MANAGER.