ex1.out

pl0修改后的源程序和报告 （1） 修改后的PL/0语言文本。包含词法分析（正规式）

    0  const m = 7, n = 85;
    1  var x, y, z, q, r;
    1  
    1  procedure multiply;
    1  var a, b;
    2  	procedure plus;
    2  	var ss;
    3  	    procedure plusplus;
    3  		var s;
    4  		begin
    5  			s := ss;
    7  		end;

    4 INT	0	4
    5 LOD	1	3
    6 STO	0	3
    7 OPR	0	0

    8  	begin
    9  		ss :=x
   10  	end;

    8 INT	0	4
    9 LOD	2	3
   10 STO	0	3
   11 OPR	0	0

   12  
   12  begin
   13  	a := x; b := y; z := 0;
   19  	while b > 0 do
   23  	begin
   23  		if odd b then z := z + a;
   30  		a := 2 * a; b := b / 2;
   38  	end
   38  end;

   12 INT	0	5
   13 LOD	1	3
   14 STO	0	3
   15 LOD	1	4
   16 STO	0	4
   17 LIT	0	0
   18 STO	1	5
   19 LOD	0	4
   20 LIT	0	0
   21 OPR	0	11
   22 JPC	0	39
   23 LOD	0	4
   24 OPR	0	6
   25 JPC	0	30
   26 LOD	1	5
   27 LOD	0	3
   28 OPR	0	2
   29 STO	1	5
   30 LIT	0	2
   31 LOD	0	3
   32 OPR	0	4
   33 STO	0	3
   34 LOD	0	4
   35 LIT	0	2
   36 OPR	0	5
   37 STO	0	4
   38 JMP	0	19
   39 OPR	0	0

   40  begin
   41  	x := n; y := m; call plusplus;
 ^
Error  11: Undeclared identifier.
   45  end.

   40 INT	0	8
   41 LIT	0	85
   42 STO	0	3
   43 LIT	0	7
   44 STO	0	4
   45 OPR	0	0

   46