gEDA-dev: Re: Verilog: $fscanf and $sscanf don't correctly reportmatch count

[Stephen Williams <steve-at-NOSPAMicarus_dot_com>]

This is a good candidate for filing as a bug report in the bugs
database. I agree that it appears wrong, so by all means file it.

Roger Williams wrote:
> Using Icarus Verilog version 0.9.devel ($Name: s20070227 $),
> $fscanf and $sscanf don't correctly return the number of input arguments
> successfully matched by the specified format, as defined in Std 1364-2001:
> 
>     The number of successfully matched and assigned input items is
>     returned in code; this number can be 0 in the event of an early
>     matching failure between an input character and the control
>     string...
> 
> Instead, they always return the argument count, even if none of them were
> matched in the input.  The behaviour can be readily demonstrated:
> 
> $ cat bar.v
> 	`define EOF -1
> 
> 	module bar;
> 	   integer line, rc, file, a, b, c;
> 	   reg [8*256:1] str;
> 
> 	   initial begin
> 	      file = $fopen ("bar_tests.v_vec", "r");
> 	      if (file == 0)
> 		 $finish;
> 	      for (line = 1; line <= 5; line = line + 1) begin
> 		 rc = $fgets (str, file);
> 		 if (rc == `EOF) 
> 		    $finish;
> 		 rc = $sscanf (str, "%h %h %h\n", a, b, c);
> 		 $display ("\tLine %d matches %d args: %h %h %h", line, rc, a, b, c);
> 	      end
> 	      $fclose (file);
> 	      $finish;
> 	   end
> 	endmodule
> 
> $ cat bar_tests.v_vec
> 	0       1       2
> 	3       4       5       // comment at end
> 	6       7
> 	// another comment
> 	9       a       b
> 
> $ iverilog -obar.vvp -tvvp bar.v; vvp bar.vvp
>         Line           1 matches           3 args: 00000000 00000001 00000002
>         Line           2 matches           3 args: 00000003 00000004 00000005
>         Line           3 matches           3 args: 00000006 00000007 00000000
>         Line           4 matches           3 args: 00000000 00000000 00000000
>         Line           5 matches           3 args: 00000009 0000000a 0000000b
> 
> I would expect the behaviour I observe when I compile the same code with ModelSim:
> 
> #       Line           1 matches           3 args: 00000000 00000001 00000002
> #       Line           2 matches           3 args: 00000003 00000004 00000005
> #       Line           3 matches           2 args: 00000006 00000007 00000005
> #       Line           4 matches           0 args: 00000000 00000007 00000005
> #       Line           5 matches           3 args: 00000009 0000000a 0000000b
> 


-- 
Steve Williams                "The woods are lovely, dark and deep.
steve at icarus.com           But I have promises to keep,
http://www.icarus.com         and lines to code before I sleep,
http://www.picturel.com       And lines to code before I sleep."



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