CODEWITHSUNDEEP
system-verilog
haykp
haykp

Reputation: 445

How to initi SV queue with binary values

I have an queue, which I want to init with the binary value. What is the best way to do that?

logic serial_frame[$]; // Want to init with 0010_0000_1000_0

Upvotes: 0

Views: 377

Answers (1)

dave_59
dave_59

Reputation: 42698

There are a couple of ways to do this.

  • Array Concatenation: { list of values for each queue element }

    serial_frame = {0,0,1,0,  0,0,0,0, 1,0,0,0, 0}; // first element is serial_frame[0]

  • Bit-stream cast: uses a type to reformat source to target type

    typedef logic bitstream_t[$];
serial_frame = bitstream_t'(13'b0010_0000_1000_0);

    The MSB of the source becomes serial_frame[0]. The size of the target must be adjustable to the size of the target. (not a problem with 1-bit queue, but would be an error if you had a queue of 8-bit bytes)

  • Streaming operator (unpack). You can chose the order of the stream

    {>>{serial_frame}} = 13'b0010_0000_1000_0; // same ordering as bit-stream cast
{<<{serial_frame}} = 13'b0010_0000_1000_0; // reverse ordering - LSB is serial_frame[0];

    The streaming operator is probably the easiest for your situation, but be aware that for other target types, it left-justifies data unlike normal assignments which right-justifies data. It also 0-pads data when the source size is smaller than the target.

See sections 10.10 Unpacked array concatenation, 6.24.3 Bit-stream casting, and 11.4.14 Streaming operators (pack/unpack) in the IEEE 1800-2017 SystemVerilog LRM.

Upvotes: 1

Related Questions