在verilog中如何将一个大位宽的FIFO拆成多个小位宽按顺序读出
时间: 2024-02-20 18:57:10 浏览: 21
在Verilog中,可以通过以下步骤将一个大位宽的FIFO拆成多个小位宽按顺序读出:
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. 在定义的大位宽FIFO模块中,将FIFO输出连接到一个位宽为总位宽的寄存器中,并在读取时按顺序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
);
reg [31:0] out_reg;
reg [3:0] out_addr;
big_fifo fifo_inst (
.clk(clk),
.rst(rst),
.write_en(write_en),
.data_in(data_in),
.data_out(out_reg),
.read_en(read_en),
.addr(addr)
);
always @(posedge clk) begin
if (rst) begin
out_addr <= 0;
end else if (read_en) begin
case (out_addr)
4'h0: data_out <= out_reg[7:0];
4'h1: data_out <= out_reg[15:8];
4'h2: data_out <= out_reg[23:16];
4'h3: data_out <= out_reg[31:24];
default: data_out <= 8'h00;
endcase
out_addr <= out_addr + 1;
end
end
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,使用了一个寄存器将FIFO输出保存下来,并在读取时按顺序选择需要读取的小位宽。需要注意的是,为了方便起见,我们使用了Verilog的case语句来选择小位宽,这在实际设计中可能不太适用。