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{
With this unit, it doesn't matter if the overlay is separate,
or tacked onto the end of the .EXE file -- the program will
run either way.
As written, this unit also uses OVERXMS, a PD unit written
Wilbert Van Leijen. Floating around the BBS's as OVERXMS.ZIP
You may delete the references to XMS.
The XMS stuff is in there because the program I copied this
code from will run on a 486 and just about all of the college
machines have XMS memory -- few if any have EMS. }
{$A-,B+,D-,F+,I-,L-,N-,O-,Q+,R-,S-,V-}
UNIT RVOVRLAY;
{ This unit starts the overlay manager }
INTERFACE
Const
ovrNoXMSDriver = -7; { No XMS driver installed }
ovrNoXMSMemory = -8; { Insufficient XMS memory available }
IMPLEMENTATION
USES DOS, OVERLAY;
{ OVERXMS - Loads overlays in XMS.
Assembly-language portion written by Wilbert van Leijen }
Procedure OvrInitXMS; External;
{$L OVERXMS.OBJ }
Function Exist(Filename:string):boolean;
{returns true if file exists}
var Inf: SearchRec;
begin
FindFirst(Filename,AnyFile,Inf);
Exist := (DOSError = 0);
end; {Func Exist}
Procedure S_Write (Msg : string);
BEGIN {Dirty trick to generate less code}
Write (msg);
END;
Procedure WriteOvrErrMsg;
VAR
garbage:char;
BEGIN
WRITE ('Overlay error: ',OvrResult,' ');
IF (OvrResult = ovrOk) THEN S_WRITE ('Ok - No error');
IF (OvrResult = ovrError) THEN S_WRITE ('Missing Overlay error');
IF (OvrResult = ovrNotFound) THEN S_WRITE ('Overlay file not found');
IF (OvrResult = ovrNoMemory) THEN S_WRITE ('No Memory for overlays');
IF (OvrResult = ovrIOError) THEN S_WRITE ('Overlay IO Error');
IF (OvrResult = ovrNoEMSDriver) THEN S_WRITE ('No EMS Driver');
IF (OvrResult = ovrNoEMSMemory) THEN S_WRITE ('No EMS Memory');
IF (OvrResult = ovrNoXMSDriver) THEN S_WRITE ('No XMS Driver');
IF (OvrResult = ovrNoXMSMemory) THEN S_WRITE ('No XMS Memory');
S_WRITE (^M^J);
read (garbage);
If OvrResult <> OvrOK THEN HALT (98);
END; { Procedure WriteOvrErrMsg }
BEGIN { main }
IF (lo(DosVersion) < 3) THEN
BEGIN
WriteLn ('You are using DOS version ',Lo(DosVersion),
'.',Hi(DosVersion));
Writeln ('Mulesoft Revenge requires DOS v3.0 or greater.');
HALT (99);
END;
{ Start overlay manager and assume that overlay is in
the .EXE file. If not found in .EXE file, assume the
overlay file is separate from the .EXE file. }
OVRINIT (paramstr(0));
If (OvrResult = ovrError) THEN { Overlay not at end of .EXE file }
OVRINIT (copy(paramstr(0), 1, Length(paramstr(0))-3) + 'OVR');
IF (OvrResult <> OvrOk) THEN
WriteOvrErrMsg
ELSE { Try to load the overlay into XMS memory }
BEGIN
OvrInitXms;
IF (OvrResult <> OvrOk) THEN
OvrInitEms;
END;
END.
{------------------------- snip, snip ----------------------------}
Here is the .OBJ file that goes with this file ...
you will need XX3402 o decode this output:
Cut this out to a file named OVERXMS.XX.
Execute XX3402 d OVERXMS.XX
You will then get the file OVERXMS.OBJ to compile this unit
*XX3402-000913-020294--72--85-48736-----OVERXMS.OBJ--1-OF--1
U+o+0qxqNL7sPLAiEJBBFMUU++++53FpQa7j623nQqJhMalZQW+UJaJmQqZjPW+n9X8NW-A+
ECafC26Q0qxqNL7sPLAiEJBBnMU1+21dH7M0++-cW+A+E84IZUM+-2F-J234a+Q+G-c++U2-
ytM4++F1HoF3FNU5+0Wi+EA-+MKAJ++7I373FYZMIoJ5++V3K2ZII37DEk+7HpNGIYJHJIlI
++hDJZ71HoF3H2ZHJ++AHpNGF2xHG23CF2l3++dDJZ76FI3EHp75++dDJZ7GFI32EZJ4+0OE
2E+++UdDJZ77HYZIK2pHCE2+xcU2+20W+N4UgU20++093VU+h+fz5U++l+M2+8A++6k4+U19
Aw+nocgS+++15U++UwAEXgAa+kM6+6DG+0O95Us+0xhptfg+-DTnYY8o0TwS+++9k5E2WFMM
+ABJWymCFUMacEU+ckU+Aw0X0U0V4+0X1++acFM+cks+7e2M+8AE+1D+cl6+clE+7e2E+8AK
+9E9jUU+zls+++j+R+F6ukGEiDnzLQc0+0O93UU+xw6-+5E4EWPz-UU+WFM6+1D+ckc+ckk+
cks+cE++cl++cFU+cl6+WHsI+6YS3U0o0vs6+DwS+++1ycDH++j+R+9skzb1JMjgcE++AwY1
-U++-F++Xg-EEGOV1U+9k5LhAxgnzkRFcE++7eAE+0O75VU+7cYy3U-HJkM4zls+++RTKmP5
-V++++1rq566u4jzQUBNsgy9tJr1Aw+v-U++REF6uqOEi+-1nGwwU5E4iDbzupSEi--1nGy7
5U++X+M0+CWmzbI4iDXzunyEu5PzQl093VU+h+fz5U++iDnzumeEWls++9EynG55-U++HU0A
1U6+l+M++8A2+6k4-U15-U++++0A1U6+Aw0X++19RdnW+AE0J+5203E-l+lI+QED-U20l-A4
+E925+M--AEU-U2-l2BI+QF9J+52KJE-l3tI+QFVJ+52N3E-l4hI+QFmJ+52RpE-l5dI+QG-
J+52VZE-l6dI+QGiJ+52gpE-l9NI+QGtJ+52j+M--gGzJ+52kZE-lAJI+QH7J+52nJE-lB7I
+QHKJ+52uEM--AHj-U2-lEQ4+EP35EM--wIx-U23lJhI+QJTJ+53QpE-lLZI+QK1-U23lMg4
+ET3XJE0lN24+ET3ZEM-+gKMJ+53b3E-lO+4+E93cZE0lOM4+E93ekM-+z88+U++R+++
***** END OF BLOCK 1 *****
{--------------------- OVERXMS.ASM --------------------- }
{ NEED MASM,TASM to compile }
TITLE Turbo Pascal XMS support for loading overlays - By Wilbert van Leijen
PAGE 65, 132
LOCALS @@
Data SEGMENT Word Public
ASSUME DS:Data
; XMS block move record
XmsMoveType STRUC
BlkSize DD ?
SrcHandle DW ?
SrcOffset DD ?
DestHandle DW ?
DestOffset DD ?
XmsMoveType ENDS
; TP overlay manager record
OvrHeader STRUC
ReturnAddr DD ? ; Virtual return address
FileOfs DD ? ; Offset into overlay file
CodeSize DW ? ; Size of overlay
FixupSize DW ? ; Size of fixup table
EntryPts DW ? ; Number of procedures
CodeListNext DW ? ; Segment of next overlay
LoadSeg DW ? ; Start segment in memory
Reprieved DW ? ; Loaded in memory flag
LoadListNext DW ? ; Segment of next in load list
XmsOffset DD ? ; Offset into allocated XMS block
UserData DW 3 DUP(?)
OvrHeader ENDS
XmsDriver DD ? ; Entry point of XMS driver
ExitSave DD ? ; Pointer to previous exit proc
XmsMove XmsMoveType <>
OvrXmsHandle DW ? ; Returned by XMS driver
Extrn PrefixSeg : Word
Extrn ExitProc : DWord
Extrn OvrResult : Word
Extrn OvrCodeList : Word
Extrn OvrDosHandle : Word
Extrn OvrHeapOrg : Word
Extrn OvrReadBuf : DWord
Data ENDS
Code SEGMENT Byte Public
ASSUME CS:Code
Public OvrInitXMS
ovrIOError EQU -4
ovrNoXMSDriver EQU -7
ovrNoXMSMemory EQU -8
OvrXmsExit PROC
; Release handle and XMS memory
MOV DX, [OvrXmsHandle]
MOV AH, 10
CALL [XmsDriver]
; Restore pointer to previous exit procedure
LES AX, [ExitSave]
MOV Word Ptr [ExitProc], AX
MOV Word Ptr [ExitProc+2], ES
RETF
OvrXmsExit ENDP
AllocateXms PROC
; Determine the size of the XMS block to allocate:
; Walk the CodeListNext chain
; Store the total codesize in DX:AX
XOR AX, AX
XOR DX, DX
MOV BX, [OvrCodeList]
@@1: ADD BX, [PrefixSeg]
ADD BX, 10h
MOV ES, BX
ADD AX, ES:[OvrHeader.CodeSize]
ADC DX, 0
MOV BX, ES:[OvrHeader.CodeListNext]
OR BX, BX
JNZ @@1
; Obtain number of kilobytes to allocate
MOV BX, 1024
DIV BX
XCHG DX, AX
INC DX
; Allocate the block
MOV AH, 9
CALL [XmsDriver]
OR AX, AX
JZ @@2
MOV [OvrXmsHandle], DX
@@2: RETN
AllocateXms ENDP
; Function XmsReadFunc(OvrSeg : Word) : Integer; Far;
XmsReadFunc PROC
; Swap the code from XMS to the heap
PUSH BP
MOV BP, SP
MOV ES, [BP+6]
MOV AX, ES:[OvrHeader.CodeSize]
MOV Word Ptr [XmsMove.BlkSize], AX
XOR AX, AX
MOV Word Ptr [XmsMove.BlkSize+2], AX
MOV AX, [OvrXmsHandle]
MOV [XmsMove.SrcHandle], AX
MOV AX, Word Ptr ES:[OvrHeader.XmsOffset]
MOV Word Ptr [XmsMove.SrcOffset], AX
MOV AX, Word Ptr ES:[OvrHeader.XmsOffset+2]
MOV Word Ptr [XmsMove.SrcOffset+2], AX
XOR AX, AX
MOV [XmsMove.DestHandle], AX
MOV Word Ptr [XmsMove.DestOffset], AX
MOV AX, ES:[OvrHeader.LoadSeg]
MOV Word Ptr [XmsMove.DestOffset+2], AX
MOV AH, 11
LEA SI, XmsMove
CALL [XmsDriver]
OR AX, AX
JZ @@1
DEC AX
JMP @@2
@@1: MOV AX, ovrIOError
@@2: POP BP
RETF 2
XmsReadFunc ENDP
; Copy an overlaid unit from the heap to XMS
; If successful, carry flag is cleared
; In/Out:
; BX:DI = offset into XMS memory block
CopyUnitToXms PROC
; XMS requires that an even number of bytes is moved
MOV DX, ES:[OvrHeader.CodeSize]
TEST DX, 1
JZ @@1
INC DX
INC ES:[OvrHeader.CodeSize]
; Get the fields of the XMS block move structure
@@1: MOV Word Ptr [XmsMove.BlkSize], DX
XOR AX, AX
MOV Word Ptr [XmsMove.BlkSize+2], AX
MOV [XmsMove.SrcHandle], AX
MOV Word Ptr [XmsMove.SrcOffset], AX
MOV AX, [OvrHeapOrg]
MOV Word Ptr [XmsMove.SrcOffset+2], AX
MOV AX, [OvrXmsHandle]
MOV [XmsMove.DestHandle], AX
MOV Word Ptr [XmsMove.DestOffset], DI
MOV Word Ptr [XmsMove.DestOffset+2], BX
MOV AH, 11
LEA SI, XmsMove
CALL [XmsDriver]
; Bump code size
ADD DI, DX
ADC BX, 0
; Check return code from XMS driver
OR AX, AX
JZ @@2
CLC
RETN
@@2: STC
RETN
CopyUnitToXms ENDP
OvrXmsLoad PROC
PUSH BP
MOV BP, SP
; Walk the CodeList chain
; First segment is PrefixSeg+10h+OvrCodeList
; Push each element of overlaid unit list on the stack
; Keep the size of the linked list in CX
MOV AX, [OvrCodeList]
XOR CX, CX
@@1: ADD AX, [PrefixSeg]
ADD AX, 10h
MOV ES, AX
PUSH AX
INC CX
MOV AX, ES:[OvrHeader.CodeListNext]
OR AX, AX
JNZ @@1
; Loop:
; Pop each element of the overlaid unit list from the stack
XOR BX, BX
XOR DI, DI
@@2: POP ES
PUSH CX
MOV AX, [OvrHeapOrg]
MOV ES:[OvrHeader.LoadSeg], AX
MOV Word Ptr ES:[OvrHeader.XmsOffset+2], BX
MOV Word Ptr ES:[OvrHeader.XmsOffset], DI
; Load overlay from disk
PUSH BX
PUSH DI
PUSH ES
PUSH ES
CALL [OvrReadBuf]
POP ES
POP DI
POP BX
; Flag unit as 'unloaded'; check return code
MOV ES:[OvrHeader.LoadSeg], 0
NEG AX
JC @@3
CALL CopyUnitToXms
JC @@3
POP CX
LOOP @@2
@@3: MOV SP, BP
POP BP
RETN
OvrXMSLoad ENDP
OvrInitXMS PROC
; Make sure the file's been opened
XOR AX, AX
CMP AX, [OvrDOSHandle]
JNE @@1
DEC AX ; ovrError
JMP @@5
; Check presence of XMS driver
@@1: MOV AX, 4300h
INT 2Fh
CMP AL, 80h
JE @@2
MOV AX, ovrNoXmsDriver
JMP @@5
; Get XMS driver's entry point
@@2: MOV AX, 4310h
INT 2Fh
MOV Word Ptr [XmsDriver], BX
MOV Word Ptr [XmsDriver+2], ES
CALL AllocateXms
JNZ @@3
MOV AX, ovrNoXMSMemory
JMP @@5
; Load the overlay into XMS
@@3: CALL OvrXmsLoad
JNC @@4
; An error occurred. Release handle and XMS memory
MOV DX, [OvrXmsHandle]
MOV AH, 10
CALL [XmsDriver]
MOV AX, ovrIOError
JMP @@5
; Close file
@@4: MOV BX, [OvrDOSHandle]
MOV AH, 3Eh
INT 21h
; OvrReadBuf := XmsReadFunc
MOV Word Ptr [OvrReadBuf], Offset XmsReadFunc
MOV Word Ptr [OvrReadBuf+2], CS
; ExitSave := ExitProc
; ExitProc := OvrXmsExit
LES AX, [ExitProc]
MOV Word Ptr [ExitSave], AX
MOV Word Ptr [ExitSave+2], ES
MOV Word Ptr [ExitProc], Offset OvrXmsExit
MOV Word Ptr [ExitProc+2], CS
; Return result of initialisation
XOR AX, AX
@@5: MOV [OvrResult], AX
RETF
OvrInitXMS ENDP
Code ENDS
END
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