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Table of Contents
2. TMT Pascal Language Description
2.2. Pascal Language Structure
2.2.12. Procedures and Functions
2.2.12.4. Interrupt Procedure
2.2.12.4. Interrupt
Procedure
Targets: MS-DOS only
In TMT Pascal, the Interrupt clause defines a procedure that is to be used
as an interrupt handler.
The parameters of an interrupt procedure are the CPU registers.
The following is the order of the CPU registers: EFLAGS, CS, EIP, EAX, EBX,
ECX, EDX, ESI, EDI, DS, ES, EBP. If these register variables are assigned
a new value, upon completion of the interrupt the new values will be restored
onto the actual CPU registers.
Declaration:
procedure IntProc(used registers); interrupt;
An example below shows you a simple method of working with interrupt-handlers.
program Timer1;
uses
Dos, Crt;
var
Int1CSave: FarPointer;
Time: LongInt;
// TimerHandler
procedure TimerHandler; interrupt;
var
StoreX, StoreY: Word;
begin
Inc(time);
StoreX:= WhereX;
StoreY:= WhereY;
GotoXY(1,1);
Write(time);
GotoXY(StoreX, StoreY);
Port[$20] := $20;
end;
begin
ClrScr;
Time := 0;
GetIntVec($1C, Int1CSave);
SetIntVec($1C, @TimerHandler);
Writeln;
Writeln('Type something and press "ENTER"to exit');
Readln;
SetIntVec($1C, Int1CSave);
end.
When using
Intr and MsDos,
keep in mind that the DOS interrupt handlers can deal
only with the addresses from the 1st megabyte of memory.
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