Jcompress 无损压缩、解压缩小程序 项目简介
Jcompress 是一款基于哈夫曼编码和最小堆的无损压缩、解压缩小程序,支持任何格式的文件的压缩与解压缩。Jcompress 的源代码位于 Utility 的 repository 分类下的 Jcompress 目录,后续会在 Utility 下面增加其他一些实用的小程序,比如基于 socket 的文件断点下载小程序等等。Jcompress代码实现1. 最小堆代码实现最小堆排序算法基本上是按照<数据结构>严蔚敏版的算法来实现的,其具体功能这里不再赘述,仅列出代码,读者可以参考课本自行分析之。首先是heap_min_adjust,也就是调整堆,代码如下所示:int heap_min_adjust(HuffmanNode **huffman_node_array, long data_start, long data_end){
/**
** check error for argument
*/
if(huffman_node_array==NULL || data_start<0 || data_end<0 || data_end<data_start){
printf("heap_min_adjust: argument error\n");
exit(0);
}
if(data_end==data_start) return 1;
/**
** the top of heap-min indicated by index data_start is the only element
** which need to be adjusted to make a min-heap
*/
HuffmanNode * current_data_tobe_adjust=huffman_node_array[data_start];
long current_indexof_data=data_start;
for(long cur=2*data_start;cur<=data_end;cur=2*cur){
if(cur<data_end){
/** compare the left child and right child to find the min one */
if(((huffman_node_array[cur])->data_8bit_count)>((huffman_node_array[cur+1])->data_8bit_count)){
cur+=1;
}
}
if((current_data_tobe_adjust->data_8bit_count)<=((huffman_node_array[cur])->data_8bit_count))
break;
huffman_node_array[current_indexof_data]=huffman_node_array[cur];
current_indexof_data=cur;
}
huffman_node_array[current_indexof_data]=current_data_tobe_adjust;
/**
** return 1 means everything is ok
*/
return 1;
}接下来是heap_min_construct()的代码,此函数是通过不断的调用上面的调整堆的函数来达到堆排序的目的。int heap_min_construct(HuffmanNode **huffman_node_array, long array_size){
/** valid data start from index 1 not 0 */
/**
** check error for argument
*/
if(huffman_node_array==NULL || array_size<=0 || array_size>256){
printf("heap_min_construct: argument error\n");
exit(0);
}
for(long HeapRoot=array_size/2; HeapRoot>=1;HeapRoot--){
heap_min_adjust(huffman_node_array,HeapRoot,array_size);
}
return 1;
}最后是heap_min_get2min()函数。int heap_min_get2min(HuffmanNode **huffman_node_array, HuffmanNode **min_first, HuffmanNode **min_second, long *heap_size){
/**
** check argument
**/
if(huffman_node_array==NULL){
printf("heap_min_get2min: argument error\n");
exit(0);
}
*min_first=huffman_node_array[1];
huffman_node_array[1]=huffman_node_array[*heap_size];
(*heap_size)-=1;
/** after we get the min data, we should again adjust the heap to make a min-heap */
heap_min_adjust(huffman_node_array,1,*heap_size);
*min_second=huffman_node_array[1];
huffman_node_array[1]=huffman_node_array[*heap_size];
(*heap_size)-=1;
/** the same as above*/
if(*heap_size>0){
heap_min_adjust(huffman_node_array,1,*heap_size);
}
return 1;
}
/**
** check error for argument
*/
if(huffman_node_array==NULL || data_start<0 || data_end<0 || data_end<data_start){
printf("heap_min_adjust: argument error\n");
exit(0);
}
if(data_end==data_start) return 1;
/**
** the top of heap-min indicated by index data_start is the only element
** which need to be adjusted to make a min-heap
*/
HuffmanNode * current_data_tobe_adjust=huffman_node_array[data_start];
long current_indexof_data=data_start;
for(long cur=2*data_start;cur<=data_end;cur=2*cur){
if(cur<data_end){
/** compare the left child and right child to find the min one */
if(((huffman_node_array[cur])->data_8bit_count)>((huffman_node_array[cur+1])->data_8bit_count)){
cur+=1;
}
}
if((current_data_tobe_adjust->data_8bit_count)<=((huffman_node_array[cur])->data_8bit_count))
break;
huffman_node_array[current_indexof_data]=huffman_node_array[cur];
current_indexof_data=cur;
}
huffman_node_array[current_indexof_data]=current_data_tobe_adjust;
/**
** return 1 means everything is ok
*/
return 1;
}接下来是heap_min_construct()的代码,此函数是通过不断的调用上面的调整堆的函数来达到堆排序的目的。int heap_min_construct(HuffmanNode **huffman_node_array, long array_size){
/** valid data start from index 1 not 0 */
/**
** check error for argument
*/
if(huffman_node_array==NULL || array_size<=0 || array_size>256){
printf("heap_min_construct: argument error\n");
exit(0);
}
for(long HeapRoot=array_size/2; HeapRoot>=1;HeapRoot--){
heap_min_adjust(huffman_node_array,HeapRoot,array_size);
}
return 1;
}最后是heap_min_get2min()函数。int heap_min_get2min(HuffmanNode **huffman_node_array, HuffmanNode **min_first, HuffmanNode **min_second, long *heap_size){
/**
** check argument
**/
if(huffman_node_array==NULL){
printf("heap_min_get2min: argument error\n");
exit(0);
}
*min_first=huffman_node_array[1];
huffman_node_array[1]=huffman_node_array[*heap_size];
(*heap_size)-=1;
/** after we get the min data, we should again adjust the heap to make a min-heap */
heap_min_adjust(huffman_node_array,1,*heap_size);
*min_second=huffman_node_array[1];
huffman_node_array[1]=huffman_node_array[*heap_size];
(*heap_size)-=1;
/** the same as above*/
if(*heap_size>0){
heap_min_adjust(huffman_node_array,1,*heap_size);
}
return 1;
}