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DOS: fix int08 stack for DPMI mode. #27

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DOS: fix int08 stack for DPMI mode. #27

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18 changes: 18 additions & 0 deletions iss_tim.pas
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Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,8 @@

Implementation

Var IntStack : array[0..4095] of byte;

Var TimerSpeed : DWord;
OldTimer : TSegInfo;
OldTimerCnt : DWord;
Expand Down Expand Up @@ -96,7 +98,16 @@
PUSH FS
PUSH GS
PUSHAD

{ with DPMI, the stack is not DS/ES, but a minimal 4K locked pm stack dedicated for interrupts, switch to DS }
MOV CX, SS
MOV EDX, ESP
MOV AX,CS:[BackupDS]
MOV SS, AX
LEA ESP, IntStack+4096
PUSH CX
PUSH EDX

MOV DS,AX
MOV ES,AX
MOV AX,DosMemSelector
Expand Down Expand Up @@ -129,6 +140,13 @@
MOV DX,$20 { � Interrupt request acknowledge � }
MOV AL,$20
OUT DX,AL

{restore old stack}
POP EDX
POP CX
MOV SS, CX
MOV ESP, EDX

POPAD
POP GS
POP FS
Expand Down