106 lines
2.8 KiB
Plaintext
106 lines
2.8 KiB
Plaintext
program Disassembler;
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uses Crt, Sysutils;
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var
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Op, Regs: 0 .. $f; //Opcode, and register arguments in a single variable
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X, Y: 0 .. 3; //Register arguments in separate variables
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Addr, IP, EP: word; //Address argument and instruction and end pointers
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Opcodes: array [0 .. $f] of string; //Opcodes in human readable form
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Bin: array [0 .. $ffef] of byte; //Program in binary form
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Prog: file of byte; //Program file
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begin
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//Populate the opcode array
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Opcodes [0] := 'HALT ';
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Opcodes [1] := 'RET ';
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Opcodes [2] := 'SHL ';
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Opcodes [3] := 'SHR ';
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Opcodes [4] := 'ROL ';
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Opcodes [5] := 'ROR ';
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Opcodes [6] := 'NAND ';
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Opcodes [7] := 'AND ';
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Opcodes [8] := 'OR ';
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Opcodes [9] := 'XOR ';
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Opcodes [$a] := 'LOAD ';
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Opcodes [$b] := 'STORE ';
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Opcodes [$c] := 'BREQ ';
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Opcodes [$d] := 'BRNEQ ';
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Opcodes [$e] := 'CLEQ ';
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Opcodes [$f] := 'CLNEQ ';
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//Initialise the instruction pointer
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IP := 0;
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//Read a program file and check for errors
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if ParamCount <> 1 then begin
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writeln ('Usage: disassembler program');
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exit;
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end;
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{$i-}
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assign (Prog, ParamStr (1));
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reset (Prog);
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{$i+}
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if IOResult <> 0 then begin
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writeln ('Usage: disassembler program');
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exit;
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end;
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repeat
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read (Prog, Bin [IP]);
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IP := IP + 1;
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until (eof (Prog)) or (IP = $fff0);
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//Save the end point and reinitialise the instruction pointer
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EP := IP;
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IP := 0;
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//Begin the main loop
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repeat
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//Print the memory location
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if IP < $1000 then write (' ');
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if IP < $100 then write (' ');
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if IP < $10 then write (' ');
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write (IntToHex (IP, 1), ' ');
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//Fetch the instruction and increment the instruction pointer
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//Opcode
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Op := Bin [IP] and $f0 shr 4;
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//Register arguments
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Regs := Bin [IP] and $f;
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X := Bin [IP] and $c shr 2;
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Y := Bin [IP] and 3;
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IP := IP + 1;
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//Address argument
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if Op >= $a then begin
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Addr := Bin [IP];
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Addr := Addr shl 8;
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IP := IP + 1;
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Addr := Addr + Bin [IP];
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IP := IP - 1;
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end;
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//Print the data
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write (IntToHex (Op, 1), IntToHex (Regs, 1));
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if Op >= $a then write (IntToHex (Addr, 4)) else write (' ');
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write (' ');
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//Print the instruction
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write (Opcodes [Op]);
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if Op = $b then writeln (IntToHex (Addr, 1), ', R', X)
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else begin
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if Op >= 2 then if Op <> $b then write ('R', X);
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if Op >= 6 then if Op <= 9 then write (', R', Y);
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if OP >= $c then write (', R', Y);
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if Op >= $a then write (', ', IntToHex (Addr, 1));
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writeln ();
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end;
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until (IP >= EP);
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end.
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