[sv-bc] RE: [sv-ec] query on evaluation of typecast expression

Yes, there are some problems with current implementations.

Mantis 2269 tries to define unambiguously the required behavior.

Shalom

> -----Original Message-----
> From: owner-sv-ec@server.eda.org 
> [mailto:owner-sv-ec@server.eda.org] On Behalf Of Sumay Guin
> Sent: Monday, May 12, 2008 7:26 PM
> To: sv-bc@server.eda.org; sv-ec@server.eda.org
> Subject: [sv-ec] query on evaluation of typecast expression
> 
> Hi,
> 
> 
>   1.  Consider the scenario,
>        module test(output reg [7:0] out1);
>        reg [3:0]in1,in2;
>        typedef reg[7:0] myreg;
>        always @(*)
>        begin
>        in2 = 4'b0101 ;
>        in1 = 4'b1100 ;
>        out1 = byte'(in2 -in1);
>        end
>       endmodule
>       According to my understanding the  value of out1 will 
> be  00001001 .
> 
>    2.  Consider another scenario,
>        module test(output reg [7:0] out1);
>        reg signed [3:0]in1,in2;
>        typedef reg[7:0] myreg;
>        always @(*)
>        begin
>        in2 = 4'b0101 ;
>        in1 = 4'b1100 ;
>        out1 = byte'(in2 -in1);
>        end
>       endmodule
>       According to my understanding the  value of out1 will 
> be  11111001 
> .     
>  
>   3. Consider another scenario,
>        module test(output reg [7:0] out1);
>        reg signed [3:0]in1,in2;
>        typedef reg[7:0] myreg;
>        always @(*)
>        begin
>        in2 = 4'b0101 ;
>        in1 = 4'b1100 ;
>        out1 = myreg'(in2 -in1);
>        end
>       endmodule
>       According to my understanding the  value of out1 will 
> be  11111001 
> .          
>  
> 4.  Consider another scenario,
>        module test(output reg [7:0] out1);
>        reg [3:0]in1,in2;
>        typedef reg[7:0] myreg;
>        always @(*)
>        begin
>        in2 = 4'b0101 ;
>        in1 = 4'b1100 ;
>        out1 = myreg'(in2 -in1);
>        end
>        endmodule
>        According to my understanding the  value of out1 will 
> be  00001001 .
> 
>      Stanadard simulator behaviour is conflictiing and 
> confusing for the above cases.
>      Can anyone help me to find out the correct result for 
> the above scenarios.
>      Your response is important for me.
> 
> Thanks & Regards,
> Sumay
> 
> 
> 
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