Question about '{26{sumofproducts[30]}}'

Hi,

I am new to Verilog. I read the following code. I do not understand the '{26{sumofproducts[30]}}'. Could you explain it to me?

Thanks

...........
wire signed [30:0] sumofproducts; // sfix31_E7
wire signed [56:0] sumofproducts_cast; // sfix57_E7

assign sumofproducts_cast = $signed({{26{sumofproducts[30]}}, sumofproducts});

 

On Monday, 3 December 2012 14:40:40 UTC+1, rxj...@gmail.com wrote:

Hi,



I am new to Verilog. I read the following code. I do not understand the '{26{sumofproducts[30]}}'. Could you explain it to me?



Thanks



..........

wire signed [30:0] sumofproducts; // sfix31_E7

wire signed [56:0] sumofproducts_cast; // sfix57_E7



assign sumofproducts_cast = $signed({{26{sumofproducts[30]}}, sumofproducts});

Hi,
This is the repetition operator. For example

wire [7:0] my_wire = {8{1'b0)} ; // Repeat 1'b0 8 times and return vector

Ibn your example, it is sign extending sumofproducts to 57 bits by repeating the MSB 26 times.

Hope that's clear,

Steven