在verilog中如何将一个大位宽的FIFO拆成多个小位宽读出
时间: 2024-02-20 18:57:00 浏览: 22
在Verilog中,可以通过以下步骤将一个大位宽的FIFO拆成多个小位宽读出:
1. 定义一个大位宽的FIFO,例如32位宽度的FIFO:
```
module big_fifo (
input clk,
input rst,
input write_en,
input [31:0] data_in,
output [31:0] data_out,
input read_en,
input [4:0] addr
);
reg [31:0] fifo [15:0];
reg [4:0] write_ptr, read_ptr;
reg [15:0] count;
// FIFO写入逻辑
always @(posedge clk) begin
if (rst) begin
write_ptr <= 0;
read_ptr <= 0;
count <= 0;
end else if (write_en) begin
fifo[write_ptr] <= data_in;
write_ptr <= write_ptr + 1;
count <= count + 1;
end
end
// FIFO读取逻辑
always @(posedge clk) begin
if (rst) begin
write_ptr <= 0;
read_ptr <= 0;
count <= 0;
end else if (read_en) begin
data_out <= fifo[read_ptr];
read_ptr <= read_ptr + 1;
count <= count - 1;
end
end
endmodule
```
2. 根据需要读取的小位宽,定义一个分时复用器(MUX),例如8位宽度的MUX:
```
module mux8 (
input [7:0] in0,
input [7:0] in1,
input [7:0] in2,
input [7:0] in3,
input [7:0] in4,
input [7:0] in5,
input [7:0] in6,
input [7:0] in7,
input [2:0] sel,
output [7:0] out
);
always @* begin
case (sel)
3'b000: out = in0;
3'b001: out = in1;
3'b010: out = in2;
3'b011: out = in3;
3'b100: out = in4;
3'b101: out = in5;
3'b110: out = in6;
3'b111: out = in7;
default: out = 8'h00;
endcase
end
endmodule
```
3. 在定义的大位宽FIFO模块中,将FIFO输出连接到MUX的输入端口,并在读取时选择需要读取的小位宽。例如,将32位宽度的FIFO拆成4个8位宽读出:
```
module small_fifo (
input clk,
input rst,
input write_en,
input [31:0] data_in,
output [7:0] data_out,
input read_en,
input [3:0] addr
);
wire [7:0] out0, out1, out2, out3;
wire [2:0] sel;
big_fifo fifo_inst (
.clk(clk),
.rst(rst),
.write_en(write_en),
.data_in(data_in),
.data_out({out3, out2, out1, out0}),
.read_en(read_en),
.addr(addr)
);
mux8 mux_inst (
.in0(out0),
.in1(out1),
.in2(out2),
.in3(out3),
.in4(8'h00),
.in5(8'h00),
.in6(8'h00),
.in7(8'h00),
.sel(sel),
.out(data_out)
);
assign sel = addr[1:0];
endmodule
```
在这个例子中,我们将32位宽度的FIFO拆成了4个8位宽读出,使用了一个8位宽度的MUX进行选择。需要注意的是,为了方便起见,我们使用了Verilog的数组和位宽拼接语法,将32位拆成了4个8位,这在实际设计中可能不太适用。