Hi,
Kindly help me to remove the small error in generate loop: below s the code :::
module barrel_shifter#(parameter DATA_WIDTH = 32)
( input [DATA_WIDTH-1:0] data_in,
input [$clog2(DATA_WIDTH)-1:0] shift_amount, // log2(DATA_WIDTH) bits for shift amount
input shift_right, // 0 for left shift, 1 for right shift
output reg [DATA_WIDTH-1:0] data_out
);
// Helper function to calculate log base 2 ceiling (e.g., clog2(8) = 3)
function integer clog2;
input integer value;
integer i;
begin
clog2 = 0;
for (i = 1; i < value; i = i * 2) begin
clog2 = clog2 + 1;
end
end
endfunction
// Intermediate wires for multi-stage shifting
wire [DATA_WIDTH-1:0] stage_0_out;
wire [DATA_WIDTH-1:0] stage_1_out;
// ... up to stage_N_out where N = $clog2(DATA_WIDTH) - 1
// genvar i; // Used for generate blocks
// The core idea of a barrel shifter is a series of MUX stages.
// Each stage shifts by a power of 2 (1, 2, 4, 8, ...).
// The shift_amount bits select which stages are active.
// A common implementation for synthesis uses nested conditional operators or a series of generate blocks.
// Let's use a series of 'assign' statements with conditional operators for clarity,
// which synthesize to multi-input multiplexers.
// Using a multi-stage approach (this is how it's typically synthesized)
// The `shifted_data` variable will hold the result after each stage.
reg [DATA_WIDTH-1:0] current_data;
always @(*) begin
current_data = data_in; // Start with the input data
// Iteratively apply shifts based on each bit of shift_amount
// Stage 0: Shift by 1 if shift_amount[0] is set
if (shift_amount[0] == 1'b1) begin
if (shift_right)
current_data = {1'b0, current_data[DATA_WIDTH-1:1]}; // Logical right shift
else
current_data = {current_data[DATA_WIDTH-2:0], 1'b0}; // Logical left shift
end
// Stage 1: Shift by 2 if shift_amount[1] is set
if (clog2(DATA_WIDTH) > 1 && shift_amount[1] == 1'b1) begin
if (shift_right)
current_data = {2'b0, current_data[DATA_WIDTH-1:2]};
else
current_data = {current_data[DATA_WIDTH-3:0], 2'b0};
end
// ... and so on for all bits of shift_amount
// This can be done with a loop within the always block or generate block
// for full parameterization.
// More robust parameterized loop
genvar i;
for (i = 0; i < clog2(DATA_WIDTH); i = i + 1) begin
if (shift_amount[i] == 1'b1) begin
if (shift_right) begin
// Right shift: Concatenate zeros at the MSB side
current_data = { { (1 << i) {1'b0} }, current_data[DATA_WIDTH-1 : (1 << i)] };
end else begin
// Left shift: Concatenate zeros at the LSB side
current_data = { current_data[DATA_WIDTH-1 - (1 << i) : 0], { (1 << i) {1'b0} } };
end
end
end
data_out = current_data;
end
endmodule
it is giving error :::::::::
** Error: (vlog-13069) C:\Users\sunil\Desktop\verilog\barrel_shifter\barrel_shifter.v(65): near "genvar": syntax error, unexpected genvar.
** Error: C:\Users\sunil\Desktop\verilog\barrel_shifter\barrel_shifter.v(66): (vlog-2730) Undefined variable: 'i'.