common/docs/reference/utils/shift_reg.md

shift_reg

Property	Value
Kind	module
RTL source	rtl/utils/shift_reg.sv
Availability	Synthesizable RTL

Summary

Parameterized sequential shift register.

Functional Behavior

Parameterized sequential shift register. Its exact parameters and ports are reproduced below from the implementation declaration.

Suitable Applications

Use as a small reusable datapath, state, coding, delay, or verification primitive.

Parameters

The declaration below is canonical; retain the RTL-enforced parameter range.

Parameter	Declaration
DATA_WIDTH	parameter int DATA_WIDTH = 8
SHIFT_NUM	parameter int SHIFT_NUM = 1

Interface Definition

module shift_reg #(
    parameter int DATA_WIDTH = 8,
    parameter int SHIFT_NUM  = 1
) (
    input  logic                  clk_i,
    input  logic                  rst_n_i,
    input  logic [           1:0] type_i,
    input  logic [           1:0] dir_i,
    input  logic                  ld_en_i,
    input  logic                  sft_en_i,
    input  logic [ SHIFT_NUM-1:0] ser_dat_i,
    input  logic [DATA_WIDTH-1:0] par_data_i,
    output logic [ SHIFT_NUM-1:0] ser_dat_o,
    output logic [DATA_WIDTH-1:0] par_data_o
);

Port Summary

Signal	Direction	Declaration
clk_i	input	input logic clk_i
rst_n_i	input	input logic rst_n_i
type_i	input	input logic [ 1:0] type_i
dir_i	input	input logic [ 1:0] dir_i
ld_en_i	input	input logic ld_en_i
sft_en_i	input	input logic sft_en_i
ser_dat_i	input	input logic [ SHIFT_NUM-1:0] ser_dat_i
par_data_i	input	input logic [DATA_WIDTH-1:0] par_data_i
ser_dat_o	output	output logic [ SHIFT_NUM-1:0] ser_dat_o
par_data_o	output	output logic [DATA_WIDTH-1:0] par_data_o

Integration and Use

Keep parameter values within RTL assertions and add required clocking, reset, or CDC protection at the caller boundary.

shift_reg #(
    .DATA_WIDTH(DATA_WIDTH),
    .SHIFT_NUM(SHIFT_NUM)
) u_shift_reg (
    .clk_i(clk_i),
    .rst_n_i(rst_n_i),
    .type_i(type_i),
    .dir_i(dir_i),
    .ld_en_i(ld_en_i),
    .sft_en_i(sft_en_i),
    .ser_dat_i(ser_dat_i),
    .par_data_i(par_data_i),
    .ser_dat_o(ser_dat_o),
    .par_data_o(par_data_o)
);

Dependencies and Verification

The linked RTL source is the implementation authority and contains local assertions for unsupported parameter combinations. See docs/design.md for repository-wide CDC, reset, stream, and storage contracts, and docs/verification.md for the verification matrix.