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Old 01-22-2004, 01:02 PM
Allan Herriman
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Default Verilog 2001 indexed part select in XST 6.1.3?

Hi,

Does anyone know if XST 6.1.3 supports the "indexed part select"
feature of Verilog 2001? (It's in section 4.2.1 of the LRM.)

The Xilinx documentation states explicitly that it does support this
feature, yet when I try to use it, I get this error message:

ERROR:Xst:850 - foo.v line 134: Unsupported .

Example code:

reg [7:0] bar;
wire [31:0] foo;

genvar j;
generate
for (j=0; j<8; j=j+1) begin : label
always @(posedge clk)
// error on next line:
bar[j] <= &foo[4*j +: 4];
end
endgenerate

Is there something special I have to do to enable 2001 support?

Thanks,
Allan.
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  #2 (permalink)  
Old 01-27-2004, 09:49 AM
Allan Herriman
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Default Re: Verilog 2001 indexed part select in XST 6.1.3?

On Fri, 23 Jan 2004 00:02:19 +1100, Allan Herriman
<[email protected]> wrote:

>Hi,
>
>Does anyone know if XST 6.1.3 supports the "indexed part select"
>feature of Verilog 2001? (It's in section 4.2.1 of the LRM.)
>
>The Xilinx documentation states explicitly that it does support this
>feature, yet when I try to use it, I get this error message:
>
>ERROR:Xst:850 - foo.v line 134: Unsupported .
>
>Example code:
>
>reg [7:0] bar;
>wire [31:0] foo;
>
>genvar j;
>generate
> for (j=0; j<8; j=j+1) begin : label
> always @(posedge clk)
> // error on next line:
> bar[j] <= &foo[4*j +: 4];
> end
>endgenerate
>
>Is there something special I have to do to enable 2001 support?
>
>Thanks,
>Allan.



The Xilinx support guy suggested this (inappropriate) code as a
workaround, then closed the case before I'd had a chance to respond.




module test_module(bar,foo,clk);


output [31:0] bar;
input [31:0] foo;
input clk;

reg [31:0] bar ;
wire [31:0] foo ;



genvar j;

generate
for (j = 0 ; j < 8 ; j = j + 1)
begin : label
always @ (posedge clk)
bar[j] <= &foo[4*j + 2] ;

end
endgenerate
endmodule


Regards,
Allan.
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  #3 (permalink)  
Old 02-02-2004, 07:29 PM
Steven Elzinga
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Posts: n/a
Default Re: Verilog 2001 indexed part select in XST 6.1.3?

Allan,

I believe that the code you referenced is called "Vector bit-select and
part-select addressing". The XST User Guide does state support of
"Array bit-select and part-select" which I believe is different than the
code you mentioned below. XST does not support the addressing scheme

[4*j +: 4]

that you mentioned.

best regards

Steve


Allan Herriman wrote:

>On Fri, 23 Jan 2004 00:02:19 +1100, Allan Herriman
><[email protected]> wrote:
>
>
>
>>Hi,
>>
>>Does anyone know if XST 6.1.3 supports the "indexed part select"
>>feature of Verilog 2001? (It's in section 4.2.1 of the LRM.)
>>
>>The Xilinx documentation states explicitly that it does support this
>>feature, yet when I try to use it, I get this error message:
>>
>>ERROR:Xst:850 - foo.v line 134: Unsupported .
>>
>>Example code:
>>
>>reg [7:0] bar;
>>wire [31:0] foo;
>>
>>genvar j;
>>generate
>> for (j=0; j<8; j=j+1) begin : label
>> always @(posedge clk)
>> // error on next line:
>> bar[j] <= &foo[4*j +: 4];
>> end
>>endgenerate
>>
>>Is there something special I have to do to enable 2001 support?
>>
>>Thanks,
>>Allan.
>>
>>

>
>
>The Xilinx support guy suggested this (inappropriate) code as a
>workaround, then closed the case before I'd had a chance to respond.
>
>
>
>
>module test_module(bar,foo,clk);
>
>
>output [31:0] bar;
>input [31:0] foo;
>input clk;
>
>reg [31:0] bar ;
>wire [31:0] foo ;
>
>
>
>genvar j;
>
>generate
>for (j = 0 ; j < 8 ; j = j + 1)
>begin : label
>always @ (posedge clk)
>bar[j] <= &foo[4*j + 2] ;
>
>end
>endgenerate
>endmodule
>
>
>Regards,
>Allan.
>
>


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