基于不同排序方法的快速霍夫曼编码硬件实现

针对软件霍夫曼静态编码计算量大,而动态霍夫曼编码使得解码器同样复杂的缺点,提出了一种准动态霍夫曼硬件编码器。该编码器每次对一组数据序列进行静态编码,然后将编码并行输出,从而使得编码器具有较高的编码速度,而其延迟时间仅为一次编码过程的总时间。首先,为了充分利用硬件并行特性,分别使用动态排序和静态排序两种排序网络,以适应不同场合的编码需要。然后,使用数据流驱动的硬件二叉树构建和解析结构得到信源符号对应的霍夫曼编码。最后,将储存在FIFO中的输入数据查表并输出。设计结果表明,当使用Nexys4 DDR平台时,该编码器可以工作于100MHz以上的频率,同时具有吞吐高、延迟低、编码效率高和译码器简单的特性。

Hardware Implementation of Fast Huffman Coding Based on Different Sorting Methods

Aiming at the drawback of static software Huffman coding which has large computational complexity and the problem of dynamic Huffman coding that makes the decoder more complicated,a quasi-dynamic hardware Huffman encoder was designed.This encoder encodes an array of data statically,then outputs the result parallelly which guarantees that it has a high encoding speed,and its dalay time is only the total time of an encoding process.First,for taking advantage of parallelism of hardware,static and dynamic sorting network are both implemented to meet different encoding demands.Then,a hardware binary tree building unit and a resolving unit driven by data flow are implemented to get the final Huffman codes.Finally,the Huffman codes are outputted based on data stored in FIFO.The design results illustrate that,this quasi-dynamic based on Nexys4 platform shows advantages of high working frequency (over 100MHz),high throughput,low latency and can simplify the design of decoder.