Hi everyone,

I was under the impression that the bit-order of values in SystemVerilog 
was left-to-right: MSbit-to-LSbit.

Recently, I wrote up a 11-bit-wide multiplexer:

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module test_mux( input logic [10:0] input_a,

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                 input logic  override,

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               output logic [10:0] output_c);

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parameter [10:0] constant = 11'h00F;                                            

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    assign output_c = (override) ?

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                        constant :

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                        input_a;

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endmodule

expecting the more-significant bits to be zeros and the last four 
less-significant bits to be ones. When I synthesized it and visualized 
the result, though, I got the unexpected constant 11'h780 as my constant 
input.

I tried an alternative:

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parameter [10:0] constant = 11'h00F;

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always_comb

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begin

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    integer i;

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    for (i = 0; i < 11; i = i + 1)       

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    begin

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    output_c[i] = (override) ?

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                       constant[i] :

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                       input_a[i];

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    end

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end

and got the expected constant input to be 11'hf.

(a) Are the two above code snippets not the same??
(b) What is the expected bit-order in Quartus?

I'm ruling out that the RTL viewer is just rendering the values 
incorrectly. To do so, for the unexpected result, I expanded the mux 
input and saw that mux[0]: 1, mux[1]: 1 ... mux[10]:0, which would rule 
out that Quartus' RTL viewer is just rendering the result incorrectly.

Thanks for taking a look, and I'd appreciate any leads on this!

Cheers!