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Assembly Source File | 1992-01-31 | 21.9 KB | 523 lines

;**************************************************************************** ; XMS.ASM - Extended memory interface for QuickBASIC programs. ; ; (C) Copyright 1992 by Sequential Software. All rights reserved. ; Author: Robin Duffy. ; ; See the headers for each public routine on calling syntax and operating ; notes. Use of extended memory requires HIMEM.SYS to be installed via ; CONFIG.SYS and a 80286 or later processor. Each procedure may be ; called at any time, even if no XMS is installed on the host machine. ; ; Assembled with Turbo Assembler 2.5 ;**************************************************************************** .Model Medium, Basic .Data XError db 80h ;Storage for errors, assumes no XMS XMSThere dw 0 ;XMS available flag, assumes no XMS XMove dw 8 Dup(?) ;Buffer for array move routines .Code XMSDriver dw ?,? ;Local storage for HIMEM entry point Public InitXMS ;**************************************************************************** ; Procedure to check for HIMEM.SYS and initialize a few things. This routine ; must be called prior to calling any of the other procedures. ; ; Syntax: CALL InitXMS(There%, MemSize%) ; Returns: There% = 0 No XMS available ; = -1 XMS available ; ; MemSize% = Size of available XMS in K bytes. ; Valid only if There% is not zero. ;**************************************************************************** Proc InitXMS Uses ES, There:Ptr Word, MemSize:Ptr Word Mov AX,4300h ;Prepare to do installation check Int 2fh ;Use the multiplex interrupt Cmp AL,80h ;Is HIMEM.SYS installed? Jnz InitExit ;Nope, get on out Mov AX,4310h ;Get the driver entry point Int 2fh Mov CS:XMSDriver,BX ;Store the offset of entry point Mov BX,ES Mov CS:XMSDriver[2],BX ;And the segment of entry point Sub BL,BL ;HIMEM does not clear this Mov AX,0800h Call DWord Ptr CS:XMSDriver ;Find available extended memory size Or BL,BL ;Did an error occur? Jnz InitExit ;Yes, so get out now Cmp AX,0 ;Is there any left for us? Jz InitExit ;No, exit now Mov BX,MemSize Mov [BX],AX ;Report the available size Dec XMSThere ;Mark our flag to -1 (XMS is good) Mov XError,0 ;Clear the error variable InitExit: Mov AX,XMSThere Mov BX,There Mov [BX],AX ;Report results to BASIC Ret ;And return InitXMS EndP Public GetXMS ;*************************************************************************** ; Procedure to allocate extended memory for the program. Because this is a ; function, it must be declared before it may be used. ; Syntax: Handle% = GetXMS(Size%) ; where Handle% receives the XMS handle. All further references to ; this block require this handle (much like DOS file handles). A ; handle of 0 means an error allocating the memory. This system ; allows multiple blocks to be managed by the parent program. ; ; Size% is the requested memory size in K bytes. ;*************************************************************************** GetXMS Proc Amount:Ptr Cmp XMSThere,-1 ;Any point in continuing? Jnz GetExit ;Nope. Mov BX,Amount Mov DX,[BX] ;Get the K requested by user Sub BL,BL Mov AX,0900h Call DWord Ptr CS:XMSDriver ;Ask HIMEM for it Mov XError,BL ;Save error code Cmp AL,1 ;Was it allocated? Jz AllOK ;Yes, go return handle Sub DX,DX ;Otherwise return handle of zero AllOK: Mov AX,DX ;Return handle as function output GetExit: Ret ;Return to BASIC GetXMS EndP Public FreeXMS ;*************************************************************************** ; Procedure to release extended memory blocks. ; ; Syntax: CALL FreeXMS(Handle%) ; where Handle% is the block handle assigned by GetXMS. This should ; be called prior to exiting your program. Unlike conventional ; memory, extended memory is not automatically released by DOS ; when the program ends. The memory remains allocated. ;*************************************************************************** FreeXMS Proc Uses SI, Handle:Ptr Word Cmp XMSThere,-1 ;Any point in continuing? Jnz FreeExit ;Nope. Mov SI,Handle Call CheckHandle ;Make sure it is a valid handle Cmp XError,0 ;Error occur? Jnz FreeExit ;Yes, get out now! Mov DX,[SI] ;Place user handle in DX Sub BL,BL Mov AX,0a00h Call DWord Ptr CS:XMSDriver ;Tell HIMEM to release the block Mov XError,BL ;Save error code FreeExit: Ret ;And return to BASIC FreeXMS EndP Public Array2XMS ;**************************************************************************** ; Procedure to move a block of memory from conventional to XMS memory. ; ;Syntax: CALL Array2XMS(BYVAL FromSeg%, BYVAL FromOffset%, Handle%, NumBytes&) ; or ; CALL Array2XMS(SEG Array(1), Handle%, Numbytes&) ; ; FromSeg% = Segment of source block ; FromOffset% = Offset of source block ; Handle% = XMS handle assigned by GetXMS ; NumBytes& = number of bytes to move (must be even) ; if a constant is used, it must be declared long ; ;**************************************************************************** Array2XMS Proc Uses SI, SSeg:Ptr Word, SOff:Ptr Word, Handle:Ptr Word,\ Bytes:Ptr Word Cmp XMSThere,-1 ;Any point in continuing? Jnz Mov1Exit ;Nope. Mov SI, Handle ;Pass handle address to CheckHandle Call CheckHandle ;See if the handle is defined Cmp XError,0 ;If error then exit Jnz Mov1Exit ;Exit with error already set Mov SI,Offset XMove ;Get location of our XMS structure Mov BX,Bytes ;Starts with number of bytes to move Mov AX,[BX] ;Read low word Mov DX,[BX+2] ;Read high word (long integer) Test AX,1 ;Is it odd? Jz IsEven ;No, it's OK Dec AX ;Force it even IsEven: Mov [SI],AX ;Load low word of number of bytes Mov [SI+2],DX ;Load the high word Mov Word Ptr [SI+4],0 ;Source handle is conventional memory Mov BX,SOff ;Load source offset Mov [SI+6],BX Mov BX,SSeg ;Load source segment Mov [SI+8],BX Mov BX,Handle ;Load destination XMS handle Mov AX,[BX] Mov [SI+10],AX Mov Word Ptr [SI+12],0 ;Offset 0 into XMS block Mov Word Ptr [SI+14],0 Sub BL,BL Mov AX,0b00h ;Ask HIMEM to do it for us Call DWord Ptr CS:XMSDriver Mov XError,BL ;Save the error code Mov1Exit: Ret ;Back to the BASIC's.... Array2XMS EndP Public XMS2Array ;*************************************************************************** ; Procedure to move a block from XMS to conventional memory. ; ; Syntax: CALL XMS2Array(Handle%, BYVAL ToSeg%, BYVAL ToOffset%, NumBytes&) ; or ; CALL Array2XMS(Handle%, SEG Array(1), Numbytes&) ; ; Handle% = XMS handle assigned by GetXMS ; ToSeg% = Segment of destination block ; ToOff% = Offset of destination block ; NumBytes& = number of bytes to move (must be even) ;**************************************************************************** XMS2Array Proc Uses SI, Handle:Ptr Word, ToSeg:Ptr Word, ToOff:Ptr Word,\ Bytes:Ptr Word Cmp XMSThere,-1 ;Any point in continuing? Jnz Mov2Exit ;Nope. Mov SI, Handle ;Pass handle address to CheckHandle Call CheckHandle ;See if the handle is defined Cmp XError,0 ;If error then exit Jnz Mov2Exit ;Exit with error already set Mov SI,Offset XMove ;Get location of our XMS structure Mov BX,Bytes ;Starts with number of bytes to move Mov AX,[BX] ;Read the low word Mov DX,[BX+2] ;Read the high word (long integer) Test AX,1 ;Is it odd? Jz Is2Even ;They read the manual again! Dec AX ;Force it even Is2Even: Mov [SI],AX ;Load low word Mov [SI+2],DX ;Now the high one Mov BX,Handle ;Load the XMS source block handle Mov AX,[BX] Mov [SI+4],AX Mov Word Ptr [SI+6],0 ;Offset 0 into XMS block Mov Word Ptr [SI+8],0 Mov Word Ptr [SI+10],0 ;Destination is conventional memory Mov BX,ToOff ;Load destination offset Mov [SI+12],BX Mov BX,ToSeg ;Load destination segment Mov [SI+14],BX Sub BL,BL Mov AX,0b00h ;Ask HIMEM to do it for us Call DWord Ptr CS:XMSDriver Mov XError,BL ;Save the error code Mov2Exit: Ret ;Back to the BASIC's.... XMS2Array EndP Public XGetElement ;*************************************************************************** ; Procedure to return any continuous portion of an array stored in XMS. ; ; Syntax: CALL GetElement(Handle%, Variable, EleLen%, EleNum%) ; where Handle% - handle assigned by GetXMS ; Variable - variable (TYPE, fixed string, or integer) to set ; EleLen% - length of the variable in bytes ; EleNum% - element number to retrieve ; ; Variable can be any variable type except a conventional string. It ; should be noted that EleLen% should be even. Also, this procedure ; assumes the first element of the array is element number one. That is, ; assume all arrays are one-based. ;*************************************************************************** XGetElement Proc Uses SI, Handle:Ptr Word, Vari:Ptr Word, EleLen:Ptr Word,\ EleNum:Ptr Word Cmp XMSThere,-1 ;Any point in continuing? Jnz GEExit ;Nope. Mov SI, Handle ;Pass handle address to CheckHandle Call CheckHandle ;See if the handle is defined Cmp XError,0 ;If error then exit Jnz GEExit ;Exit with error already set Mov XError,0a7h ;Assume a syntax error Mov SI,Offset XMove ;Location of our move buffer Sub DX,DX ;Make sure DX is zero (oops!) Mov BX,EleLen ;Get the length of the variable Mov AX,[BX] ;Load into AX Test AX,1 ;Is it odd? Jz Is3Even ;No, it's OK. Dec AX ;Make it even Or AX,AX ;It's not zero, is it? Jnz Is3Even ;No, it's OK. Jmp Short GEExit ;It is zero, leave now Is3Even: Mov BX,EleNum ;Get the element to get Mov CX,[BX] ;into CX Jcxz GEExit ;If element is 0, forget it Mov XError,0 ;We are OK here, clear error status Mov [SI],AX ;EleLen is number of bytes to move Mov [SI+2],DX ;High word should be zero..... Dec CX ;Adjust CX to zero base Mul CX ;Find offset into block ;DX:AX holds 32 bit offset into block Mov BX,Handle ;Find our source handle Mov CX,[BX] Mov [SI+4],CX ;Move handle into buffer Mov [SI+6],AX ;Low word of 32 bit offset Mov [SI+8],DX ;High word of offset Mov Word Ptr [SI+10],0 ;Destination handle is convential mem Mov BX,Vari ;Get offset of variable from BASIC Mov [SI+12],BX ;Load offset into structure Mov [SI+14],DS ;Set segment to DS Sub BL,BL Mov AX,0b00h ;Ask HIMEM to do it for us Call DWord Ptr CS:XMSDriver Mov XError,BL ;Save the error code GEExit: Ret ;Back to BASIC XGetElement EndP Public XSetElement ;*************************************************************************** ; Procedure to set any continuous portion of an array stored in XMS. ; ; Syntax: CALL SetElement(Handle%, Variable, EleLen%, EleNum%) ; where Handle% - handle assigned by GetXMS ; Variable - variable (TYPE, fixed string, etc) to place in XMS ; EleLen% - length of the variable in bytes ; EleNum% - element number to write to ; ; Variable can be any variable type except a conventional string. It ; should be noted that EleLen% should be even. Also, this procedure ; assumes the first element of the array is element number one. That is, ; assume all arrays are one-based. ;*************************************************************************** XSetElement Proc Uses SI, Handle:Ptr Word, Vari:Ptr Word, EleLen:Ptr Word,\ EleNum:Ptr Word Cmp XMSThere,-1 ;Any point in continuing? Jnz SEExit ;Nope. Mov SI, Handle ;Pass handle address to CheckHandle Call CheckHandle ;See if the handle is defined Cmp XError,0 ;If error then exit Jnz SEExit ;Exit with error already set Mov XError,0a7h ;Assume a syntax error Mov SI,Offset XMove ;Location of our move buffer Sub DX,DX ;Make sure DX is zero (oops again!) Mov BX,EleLen ;Get the length of the variable Mov AX,[BX] ;Load into AX Test AX,1 ;Is it odd? Jz Is4Even ;No, it's OK. Dec AX ;Make it even Or AX,AX ;It's not zero, is it? Jnz Is4Even ;No, it's OK. Jmp Short SEExit ;It is zero, leave now Is4Even: Mov BX,EleNum ;Get the element to write to Mov CX,[BX] ;into CX Jcxz SEExit ;If element is 0, forget it Mov XError,0 ;We are OK here, clear error status Mov [SI],AX ;EleLen is number of bytes to move Mov [SI+2],DX ;High word should be zero Dec CX ;Adjust CX to zero base Mul CX ;Find offset into block ;DX:AX holds 32 bit offset into block Mov Word Ptr [SI+4],0 ;Source handle is convential mem Mov BX,Vari ;Get offset of variable from BASIC Mov [SI+6],BX ;Load offset into structure Mov [SI+8],DS ;Set segment to DS in structure Mov BX,Handle ;Find our source handle Mov CX,[BX] Mov [SI+10],CX ;Move handle into buffer Mov [SI+12],AX ;Low word of 32 bit offset in buffer Mov [SI+14],DX ;High word of offset in buffer Sub BL,BL Mov AX,0b00h ;Ask HIMEM to do it for us Call DWord Ptr CS:XMSDriver Mov XError,BL ;Save the error code SEExit: Ret ;Back to BASIC XSetElement EndP Public XMSError ;**************************************************************************** ; Procedure to report success of last XMS operation. Because this is a ; function, It must be declared before it may be used. ; ; Syntax: C% = XMSError% ; ; returns C% = 0 Last operation successful ; C% = -1 Last operation resulted in error ; ; This function will always show an error if XMS is not available. ;**************************************************************************** XMSError Proc Mov AX,-1 ;Assume an error Cmp XMSThere,0 ;Is XMS available? Jz ExitErr ;No, exit now with error Mov BL,XError ;Load error byte in Or BL,BL ;Anything there? Jnz ExitErr ;Yes, report an error Inc AX ;Make it a 0 to show no error ExitErr: Ret ;Back to BASIC with output in AX XMSError EndP Public WhichXError ;*************************************************************************** ; Procedure that returns the current value of XError. Because this is a ; function, it must be declared before it may be used. It should be noted ; that any sucessful call to any procedure in this file will clear XError. ; ; Syntax: Code% = WhichXError% ; where Code% receives the value of XError. ;*************************************************************************** WhichXError Proc Mov AL,XError ;Load AL with the error Xor AH,AH ;Clear AH Ret ;Return to BASIC WhichXError EndP Public SetXError ;**************************************************************************** ; This procedure allows direct setting of the XError variable to force ; error codes. Useful for communications between modules. ; ; Syntax: CALL SetXError(ErrCode%) ; where ErrCode% is a value between 0 - 255 inclusive. ; ; Note: If XMS is not installed, this function will not have any effect. ;**************************************************************************** SetXError Proc ErrCode:Ptr Word Cmp XMSThere,-1 ;Can we set error codes? Jnz SetExit ;No, skip this Mov BX,ErrCode ;Get the user's error code Mov AX,[BX] ;into AX Mov XError,AL ;Load it SetExit: Ret ;Back to BASIC SetXError EndP ;**************************************************************************** ; CheckHandle - Procedure to test the validity of a user passed handle. For ; some reason HIMEM.SYS does not seem to check the validity of ; the handle on any function call but this one! If not tested ; an invalid handle will lock the machine. ; ; On Entry: SI - pointer to address of user passed handle ; ; On Exit: DX - block size associated with handle ; XError - set to invalid handle if invalid, otherwise clear ;**************************************************************************** CheckHandle Proc Near Mov DX,[SI] ;Put the handle in DX Or DX,DX ;Handle of zero? ;Note: I test for a zero handle ;becuase 0 is a valid handle for ;HIMEM (conventional memory) but is ;NOT valid for any user calls. Jnz DXOK ;It's not, go on Mov XError,0a2h ;Set "Invalid Handle" error Jmp Short CHExit ;And exit DXOK: Sub BL,BL ;Clear BL for HIMEM Mov XError,BL ;and the error code Mov AX,0e00h Call DWord Ptr CS:XMSDriver ;Ask HIMEM about this handle Cmp AX,1 ;Was it successful? Je CHExit ;Yes, exit now Mov XError,BL ;Save the error code CHExit: Ret CheckHandle EndP End