c_progarm/huffman.c

#include "stdlib.h"
#include "stdio.h"
#include "bytearray.h"
#include "string.h"

// huffman编码的实现

#define DBG_WARN printf
#define DBG_LOG printf

typedef struct _huff_tree{
  uint8_t data;
  uint8_t pos;// 位置，左为1，右为0
  uint16_t count;
  struct _huff_tree *parant;
  struct _huff_tree *left;
  struct _huff_tree *right;
}huff_tree;



typedef struct{
  huff_tree *tree;
  int index_table_index;
  huff_tree *index_table[256];
  uint16_t count_table[256];
  array_def *out;
  array_def *in;
  int in_bit_count;
  int arr_bit_index;
}huffman_def;


static int hm_calc_value_of_tree(huff_tree *t);

// 按出现频次排序
static void hm_sort_index_table(huff_tree **table,int num)
{
  for(int i=0;i<num;i++)
  {
    huff_tree *item=table[i];
    for (int j=i;j<num;j++)
    {
      if(hm_calc_value_of_tree(table[j])>hm_calc_value_of_tree(item))
      {
        table[i]=table[j];
        table[j]=item;
        item=table[i];
      }
    }
  }
}



// 打印index_table
static void hm_index_table_print(huffman_def *h){
  DBG_LOG("-----index_table-----\n");
  for(int i=0;i<h->index_table_index;i++){
    DBG_LOG("index:%d,data:%02x,count:%d\n",i,h->index_table[i]->data,h->index_table[i]->count);
  }
}


// 打印数据的编码
static void hm_data_code_print(huffman_def *h){
  huff_tree *t;
  DBG_LOG("------data code------\n");
  for(int i=0;i<h->index_table_index;i++){
    t=h->index_table[i];
    DBG_LOG("%c:",t->data);
    while(t->parant){
      DBG_LOG("%d",t->pos);
      t=t->parant;
    }
    DBG_LOG("\n");
  }
}



static void hm_calc_count(huffman_def *h,array_def *d)
{
  int num=arr_length(d);
  int index;
  memset(h->count_table,0,256);
  // DBG_LOG("calc count_table\n");
  for(int i=0;i<num;i++)
  {
    h->count_table[arr_get(d,i)]++;
  }
  // DBG_LOG("calc index_table\n");
  for(int i=0;i<256;i++)
  {
    if(h->count_table[i]>0){
      index=h->index_table_index;
      h->index_table[index]=calloc(1,sizeof(huff_tree));
      h->index_table[index]->count=h->count_table[i];
      h->index_table[index]->data=i;
      h->index_table_index++;
    }
  }
  // DBG_LOG("sort index_table\n");
  hm_sort_index_table(h->index_table,h->index_table_index);
  // hm_index_table_print(h);
}



// 计算树的值
static int hm_calc_value_of_tree(huff_tree *t)
{
  int sum=0;
  if(t->left&&t->right)
    sum=hm_calc_value_of_tree(t->left)+hm_calc_value_of_tree(t->right);
  else
    sum=t->count;
  // DBG_LOG("tree sum:%d\n",sum);
  return sum;
}



// 打印huffman树
static void hm_tree_print(huff_tree *t)
{
  if(t->left&&t->right){
    DBG_LOG("point:,count:%d\n",hm_calc_value_of_tree(t));
    hm_tree_print(t->left);
    hm_tree_print(t->right);
  }else{
    DBG_LOG("data:%d,count:%d\n",t->data,t->count);
  }

}




// 建立huffman树
static void hm_creat_tree(huffman_def *h)
{
  int tail=h->index_table_index;
  huff_tree *sub1,*sub2;
  huff_tree **table=calloc(tail,sizeof(huff_tree *));
  for(int i=0;i<tail;i++){
    table[i]=h->index_table[i];
  }
  while(tail>1){
    huff_tree *temp;
    sub1=table[tail-1];
    sub2=table[tail-2];
    // 大在左，小在右
    temp=calloc(1,sizeof(huff_tree));
    sub1->parant=temp;
    sub2->parant=temp;
    // 左为1，右为0
    if(hm_calc_value_of_tree(sub1)>hm_calc_value_of_tree(sub2)){
      temp->left=sub1;
      sub1->pos=1;
      temp->right=sub2;
      sub2->pos=0;
    }else{
      temp->left=sub2;
      sub2->pos=1;
      temp->right=sub1;
      sub1->pos=0;
    }
    table[tail-2]=temp;
    tail--;
    hm_sort_index_table(table,tail);
    // DBG_LOG("-----table-----\n");
    // for(int i=0;i<tail;i++){
    //   DBG_LOG("index:%d,count:%d\n",i,hm_calc_value_of_tree(table[i]));
    // }
  }
  h->tree=table[0];
  free(table);
}


// 删除树
static void hm_del_tree(huff_tree *t)
{
  if(t->left&&t->right){
    hm_del_tree(t->left);
    hm_del_tree(t->right);
  }
  free(t);
}

// 数据中添加一个bit
static void hm_add_bit(array_def *d,int bit,int *index)
{
  int len=arr_length(d);
  if(*index<len*8){
    uint8_t c=arr_get(d,-1);
    c|=bit<<(*index%8);
    arr_reset(d,c,-1);
  }else{
    arr_append(d,bit);
  }
  (*index)++;
}


// 根据数据添加bit
static int hm_encode_byte(huffman_def *h,uint8_t d)
{
  huff_tree *t=0;
  // 这里默认一定能找到对应的值
  for(int i=0;i<h->index_table_index;i++)
  {
    t=h->index_table[i];
    if(t->data==d)
      break;
  }
  if(t->data!=d){
    DBG_WARN("can not encode.\n");
    exit(-1);
  }

  while(t->parant){
    hm_add_bit(h->out,t->pos,&h->arr_bit_index);
    t=t->parant;
  }
  // char *str=arr_string(h->out);
  // DBG_LOG("index:%d,out data:%s\n",h->arr_bit_index,str);
  // free(str);
  return 0;
}

// 生成索引
static array_def *hm_creat_index_table(huffman_def *h)
{
  array_def *a=arr_creat();
  int temp;
  int diff;
  arr_append(a,h->index_table_index);
  hm_index_table_print(h);
  for(int i=0;i<h->index_table_index;i++)
  {
    arr_append(a,h->index_table[i]->data);
    temp=h->index_table[i]->count;
    while(temp>0){
      if(temp>=255) diff=255;
      else diff=temp;
      arr_append(a,diff);
      temp-=diff;
    }
  }
  // 填充0个数
  temp=arr_length(h->out)*8-h->arr_bit_index;
  arr_append(a,temp);
  // char *str=arr_string(a);
  // DBG_LOG("arr index table:%s\n",str);
  // free(str);
  return arr_temp(a);
}

// huffman编码
/*
压缩后数据格式
data[0]:索引表长度
data[1~n]:索引表，每个索引由值(1byte)和频次(1byte,小于255)(2byte,大于等于255,频次由两个字节相加)
data[n+1]:数据中填充0个数
data[n+2~m]:压缩后的数据

*/
array_def *hm_encode(array_def *data)
{
  int input_len=arr_length(data);
  huffman_def *h=calloc(1,sizeof(huffman_def));
  array_def *ret=0;
  h->out=arr_creat();
  // DBG_LOG("calc count\n");
  hm_calc_count(h,data);
  // DBG_LOG("creat tree\n");
  hm_creat_tree(h);
  // DBG_LOG("encode byte\n");
  for(int i=0;i<input_len;i++)
  {
    hm_encode_byte(h,arr_get(data,i));
  }
  ret=hm_creat_index_table(h);
  hm_del_tree(h->tree);
  arr_appends_from(ret,h->out);
  arr_delete(h->out);
  free(h);

  DBG_LOG("lenth_in:%d,length_encode:%d\n",input_len,arr_length(ret));
  return arr_temp(ret);
}


// 读取编码表,返回数据开始的位置
static int hm_unpack_count(huffman_def *h,array_def *d)
{
  int num=arr_get(d,0);
  int index=1;
  uint8_t temp;
  for(int i=0;i<num;i++)
  {
    h->index_table[i]=calloc(1,sizeof(huff_tree));
    h->index_table[i]->data=arr_get(d,index);index++;
    do{
      temp=arr_get(d,index);index++;
      h->index_table[i]->count+=temp;
    }while(temp==0xff);
    h->index_table_index++;
  }
  temp=arr_get(d,index);index++;
  h->in_bit_count=(arr_length(d)-index)*8-temp;
  h->in=arr_mid(d,index,arr_length(d)-index);
  // hm_index_table_print(h);
  printf("bitcount:%d,\n",h->in_bit_count);
  return index;
}


// 获取指定index的bit值
static inline int hm_get_bit(array_def *d,int index)
{
  uint8_t t=arr_get(d,index/8);
  return t&(1<<(index%8))?1:0;
}


// 对比树节点，匹配返回bit数，不匹配返回0
static inline int hm_cmp_bits(huffman_def *h,huff_tree *t)
{
  int count=0;
  // DBG_LOG("tree pos:",t->pos);
  while(t){
    // DBG_LOG("%d",t->pos);
    if(hm_get_bit(h->in,h->arr_bit_index+count)!=t->pos){
      // DBG_LOG(" |failed\n");
      return 0;
    }
    else{
      count++;
      t=t->parant;
    }
  }
  h->arr_bit_index+=count;
  // DBG_LOG(" |ok,\n");
  return count;
}


static uint8_t hm_decode_byte(huffman_def *h)
{
  huff_tree *t=h->tree;
  int bit;
  // DBG_LOG("decode:");
  while(t->left&&t->right){
    bit=hm_get_bit(h->in,h->arr_bit_index-1);
    // DBG_LOG("%d",bit);
    if(bit==t->left->pos)
      t=t->left;
    else
      t=t->right;
    h->arr_bit_index--;
  }
  // DBG_LOG(" | decode byte:%c\n",t->data);
  return t->data;
}



static int hm_calc_decode_len(huffman_def *h)
{
  int sum=0;
  for(int i=0;i<h->index_table_index;i++){
    sum+=h->index_table[i]->count;
  }
  DBG_LOG("data len for decode:%d\n",sum);
  return sum;
}



// huffman解码
/*
*/
array_def *hm_decode(array_def *data)
{
  huffman_def *h=calloc(1,sizeof(huffman_def));
  int decode_len,decode_index;
  array_def *ret=arr_creat();
  uint8_t *decode_data=0;
  uint8_t c;
  hm_unpack_count(h,data);
  hm_creat_tree(h);
  // hm_data_code_print(h);
  // hm_tree_print(h->tree);
  decode_len=hm_calc_decode_len(h);
  decode_index=decode_len;
  decode_data=calloc(decode_len+1,sizeof(uint8_t));
  h->arr_bit_index=h->in_bit_count;
  while(h->arr_bit_index>0){
    c=hm_decode_byte(h);
    decode_data[decode_index-1]=c;
    decode_index--;
  }
  DBG_LOG("del tree\n");
  hm_del_tree(h->tree);
  DBG_LOG("del h->in\n");
  //arr_delete(h->in);
  DBG_LOG("free h\n");
  free(h);
  // arr_appends(ret,decode_data,decode_len);
  DBG_LOG("decode:%s\n",decode_data);
  free(decode_data);
  return arr_temp(ret);
}