giainen.h

Huffman compression by Visual C++2008

#include "nen.h"

class Decompress : public Compress 
{
private:	
	bit_buffer buff;
public:
	Decompress();
	void convert_bin(unsigned char c);
	void decode_file(char *FileIn, char *FileOut);


};
Decompress::Decompress()
{
	for(int i=0;i<NUM_CHAR;++i)
		freq[i] = 0;
}
void Decompress::convert_bin(unsigned char c)
{	
	int i;
	for(i=0;i<NUM_BIT;++i)
		buff.content[i] = '0';
	buff.content[NUM_BIT]='\0';
	i= NUM_BIT - 1;
	while(i>=0)
	{	
		buff.content[i]=(c%2)+'0';
		c=c/2;
		i--;
	}
	buff.post = 0;

}

void Decompress::decode_file(char *NameFileIn, char *NameFileOut)
{
	int i;
	char *codes[NUM_CHAR];
	char code[NUM_CHAR];
	unsigned char c;  // luu tru byte cuoi cung
	int n;  // So ky tu co trong File truoc khi nen
	fstream FileIn(NameFileIn,ios::in|ios::binary);
	fstream FileOut(NameFileOut,ios::out|ios::binary);
	FileIn.read((char*)(&n),sizeof(n));
	for(int i=1;i<=n;++i)
	{	
		FileIn.get(unsigned char(ch));
		FileIn.read((char*)(&freq[ch]),sizeof(int)); 
	}
	int start = FileIn.tellg();
	FileIn.seekp(-1,ios::end);
	int full_bytes = FileIn.tellg() - start - 1;
	FileIn.get(c);
	FileIn.seekg(-full_bytes-2,ios::end);
	treenode *r = this->build_huffman();
	this->traverse (r, 0, code, codes);
	treenode *t=r;
	FileIn.get(ch);
	this->convert_bin(ch);
	for(i=1;i<=full_bytes;)
	{	
		if(t->left==NULL&&t->right==NULL)
		{	
			FileOut.put(t->ch);
			t = r;
		}
		else
		{
			if(buff.post<NUM_BIT&&buff.content[buff.post]=='0')
				t = t->left;
			if(buff.post<NUM_BIT&&buff.content[buff.post]=='1')
				t = t->right;
			if(buff.post==NUM_BIT)
			{
				FileIn.get(ch);
				this->convert_bin(ch);
				++i;
				buff.post = -1;
			}
			buff.post++;

		}

	}
	int remain = (int(c)==0)?NUM_BIT:int(c);
	for(;buff.post<=remain;)
	{	
		if(t->left==NULL&&t->right==NULL)
		{
			FileOut.put(t->ch);
			t = r;
		}
		else
		{
			if(buff.post<NUM_BIT&&buff.content[buff.post]=='0')
				t = t->left;
			if(buff.post<NUM_BIT&&buff.content[buff.post]=='1')
				t = t->right;
			buff.post++;

		}

	}
	FileIn.close();
	FileOut.close();

}