verilog实现huffman编码
时间: 2023-06-14 14:08:06 浏览: 369
huff.rar_Huffman Encoder_huffman verilog_huffman encoder vhdl_h
Huffman编码是一种常见的数据压缩算法,它通过将出现频率较高的字符用较短的编码表示,从而减少数据的存储空间。下面是一个Verilog实现的简单示例。
首先,我们需要定义一个结构体来表示字符以及它的频率和编码:
```
typedef struct {
logic [7:0] ascii;
logic [31:0] freq;
logic [7:0] code;
} huffman_node;
```
接下来,我们需要实现一个计算字符频率的模块。这个模块会接收一个输入字符流,统计每个字符出现的次数,并将结果存储在一个数组中:
```
module huffman_counter(
input logic clk,
input logic [7:0] in_char,
input logic reset,
output logic [7:0] out_char,
output logic done
);
// 统计字符出现频率
reg [7:0] freq [0:255];
always @(posedge clk) begin
if (reset) begin
for (int i = 0; i < 256; i++) begin
freq[i] <= 0;
end
end else begin
freq[in_char] <= freq[in_char] + 1;
end
end
// 输出出现频率最高的字符
reg [31:0] max_freq = 0;
reg [7:0] max_char;
always @(posedge clk) begin
if (reset) begin
max_freq <= 0;
max_char <= 0;
end else begin
for (int i = 0; i < 256; i++) begin
if (freq[i] > max_freq) begin
max_freq <= freq[i];
max_char <= i;
end
end
done <= 1;
end
end
assign out_char = max_char;
endmodule
```
接下来,我们需要实现一个构建Huffman树的模块。这个模块会接收字符频率数组作为输入,然后构建一棵Huffman树,并将每个字符的编码存储在一个数组中:
```
module huffman_tree(
input logic clk,
input logic [7:0] in_char,
input logic [31:0] in_freq,
input logic reset,
output huffman_node [255:0] tree,
output logic done
);
// 构建Huffman树
reg [255:0] nodes;
always @(posedge clk) begin
if (reset) begin
for (int i = 0; i < 256; i++) begin
nodes[i] = {i, in_freq[i], 0};
end
end else begin
int n = 256;
while (n > 1) begin
// 找到最小的两个节点
int min1 = -1, min2 = -1;
for (int i = 0; i < n; i++) begin
if (nodes[i].freq > 0) begin
if (min1 < 0 || nodes[i].freq < nodes[min1].freq) begin
min2 = min1;
min1 = i;
end else if (min2 < 0 || nodes[i].freq < nodes[min2].freq) begin
min2 = i;
end
end
end
// 合并两个节点
nodes[n] = {0, nodes[min1].freq + nodes[min2].freq, 0};
nodes[min1].code = 0;
nodes[min2].code = 1;
nodes[n].ascii = min1;
nodes[min1].freq = 0;
nodes[min2].freq = 0;
n = n + 1;
end
// 将编码存储到数组中
for (int i = 0; i < 256; i++) begin
tree[i] = nodes[i];
end
done <= 1;
end
end
endmodule
```
最后,我们需要实现一个编码器模块。这个模块会接收输入字符流以及Huffman编码表作为输入,然后将每个字符编码后的结果输出:
```
module huffman_encoder(
input logic clk,
input logic [7:0] in_char,
input logic reset,
input huffman_node [255:0] tree,
output logic [7:0] out_code,
output logic done
);
// 查找字符在Huffman树中的位置
reg [7:0] pos;
always @(in_char) begin
for (int i = 0; i < 256; i++) begin
if (tree[i].ascii == in_char) begin
pos <= i;
break;
end
end
end
// 输出编码
reg [7:0] code [0:255];
reg [7:0] code_len [0:255];
reg [7:0] bit_count = 0;
always @(posedge clk) begin
if (reset) begin
for (int i = 0; i < 256; i++) begin
code[i] <= 0;
code_len[i] <= 0;
end
bit_count <= 0;
end else begin
code[bit_count] <= code[bit_count] << 1 | tree[pos].code;
code_len[bit_count] <= code_len[bit_count] + 1;
bit_count <= bit_count + 1;
if (tree[pos].code == 0) begin
code[bit_count] <= 0;
code_len[bit_count] <= 0;
bit_count <= 0;
done <= 1;
end
end
end
// 输出编码
assign out_code = code[bit_count - 1];
endmodule
```
这样,我们就完成了Huffman编码的Verilog实现。需要注意的是,这只是一个简单的示例,实际应用中可能需要更复杂的实现。
阅读全文