Interested In Compression Algorithms? Here you have a cute code

[Anduril 0]

That's a compressor i made during my university practical lessons on information theory, it's a text compressor, it's only usefull for texts containing only vocals, but it can easily be adapted for the whole alphabet ^^...

 

Good luck with the comment translation!! (Catalan and Spanish...)

 

 

#include <stdio.h>#include <math.h>#include <string.h>//En argv tenemos: (1)selector de compresion/descompresion (2)Tabla de frecuencias (3)Fichero de simbolos// (4)Fichero de salidaint treureDigitsCodificacio (int*,int*,FILE*,FILE*,int*,int*);void calcularAltBaix (int*,int*,int*,int,FILE*,FILE*,int*);int codifica(char *argv[]);int descodifica(char *argv[]);int treureDigitsDescodificacio (int*,int*,int*,FILE*,FILE*);void calcularSimbol(int*,int*,int*,int,int*,FILE*,FILE*);int main (int argc,char *argv[]){	int a;	if (strcmp (argv[1],"-c") == 0)	{		a=codifica(argv);	}	else if (strcmp(argv[1],"-d") == 0)	{		a=descodifica(argv);	}return a;}	int treureDigitsCodificacio (int *al,int *ba,FILE *f_out, FILE *f_control,int *ca,int *uf)	{		//procedemos a eliminar las cifras comunes		int cont=0;		int i=0;		while ((*al/10000) == (*ba/10000))		{						fprintf(f_out,"%d",(*al/10000));			if(*uf!=0)			{				if(*ca==*al/10000)//Afegim 0s				{					for(i=0;i<*uf;i++)					{						fprintf(f_out,"%d",0);					}					i=0;					*uf=0;				}				else//Afegim 9s				{					for(i=0;i<*uf;i++)					{						fprintf(f_out,"%d",9);					}					i=0;					*uf=0;				}			}			//printf("Afegirem %d al fitxer de sortida.\n",(*al/10000));			cont++;			*al = ((*al-((*al/10000)*10000))*10)+9;			*ba = ((*ba-((*ba/10000)*10000))*10);			//printf("El nou Alt es %d.\nEl nou Baix es %d.\n",*al,*ba);			fprintf (f_control,"Alt: %d, Baix: %d\n",*al,*ba);				}		if(((*al/10000)-(*ba/10000))==1)//Calculem underflow del nombre resultant		{			*ca=*al/10000;			int at,bt;			int segundo_a=(*al-(*al/10000)*10000)/1000;			int segundo_b=(*ba-(*ba/10000)*10000)/1000;			while(segundo_a == 0 && segundo_b == 9)			{				*uf= *uf +1;				at=(*al-((*al/10000)*10000))-(segundo_a*1000);				bt=(*ba-((*ba/10000)*10000))-(segundo_b*1000);				*al=(((*al/10000)*10000)+at*10)+9;				*ba=((*ba/10000)*10000)+(bt*10);				segundo_a=(*al-(*al/10000)*10000)/1000;				segundo_b=(*ba-(*ba/10000)*10000)/1000;			}		}		return cont;	}	void calcularAltBaix (int *ra, int *al, int *ba,int N, FILE *f_simbol, FILE *f_control,int v_F[])	{		int k;		char sim;		int alt = *al;		int baix = *ba;		int rang = *ra;		sim=fgetc(f_simbol);		if (sim == 'a') k=0;		else if (sim == 'e') k=1;		else if (sim == 'i') k=2;		else if (sim == 'o') k=3;		else if  (sim == 'u') k=4;		rang = alt - baix +1;		alt = (baix + (rang * v_F[k])/ N)  -1;		if(k!=0) baix = (baix + (rang * v_F[k-1])/ N);		//printf ("Com que el simbol es %c, k val: %d\n",sim, k);		*al = alt;		*ba = baix;		*ra = rang;		fprintf (f_control,"Caracter: %c, Alt: %d, Baix: %d\n",sim,*al,*ba);	}	int codifica(char *argv[])	{		FILE *f_taula;		FILE *f_simbol;		FILE *f_out;		FILE *f_control;		f_taula = fopen (argv[2], "r");		f_simbol = fopen (argv[3], "r");		f_out = fopen (argv[4], "w");		f_control = fopen ("code.txt","w");		int alt = 99999;		int baix = 0;		int rang;		char simbol;		int cont=0;		int underflow=0,control_alt;	/*Obrir fitxers*/		simbol = fgetc(f_simbol);		/*Comprovacio de validesa del fitxer d'entrada:*/		while (simbol!=EOF)		{			cont++;		if (!(simbol == 'a' || simbol == 'e' || simbol == 'i' || simbol == 'o' || simbol == 	'u'))			{				//printf ("Fitxer d'entrada erroni, simbol %c incorrecte\n",simbol);				fclose(f_simbol);				return -1;			}				simbol = fgetc(f_simbol);		}//printf ("\n%d\n%d\n",alt,baix);		rewind (f_simbol);		//printf("Tenim un total de %d simbols per codificar.",cont);		//Escrivim Capçalera		fprintf(f_out,"TI2005-06\n");		fprintf(f_out,"%d\n",cont);		fflush(f_out);		/*Fi de la comprovacio*/		/*Tractament de la taula de freqĂÂźencies*/		int v_taula[5];		fscanf (f_taula,"%d",&v_taula[0]);		int i = 1;		while (!feof(f_taula))		{			fscanf (f_taula,"%d",&v_taula[i]);			i++;		}		/*Tractament del vector taula*/		int v_F [5];		//int v_P [5];		v_F [0]= v_taula [0];		for (i=1;i<5;i++)		{			v_F [i] = v_F [i-1] + v_taula [i];		}		int N = v_F [4];		int caracters_codificats = 0;		int ind;		for(ind = 0; ind<cont; ind++)		{			//printf("\n----------------Simbol %d-------------------\n",(cont-ind));			calcularAltBaix (〉, &alt, &baix,N, f_simbol,f_control, v_F);			//printf ("\n%d\n%d\n",alt,baix);			//procedemos a eliminar las cifras comunescaracters_codificats = caracters_codificats + treureDigitsCodificacio(&alt,&baix,f_out,f_control,&control_alt,&underflow);		}		//Introduim al fitxer de sortida la xifra mes significativa de l'ultim baix.		fprintf(f_out,"%d",(baix/10000));		//cal introduir-la al fitxer control?		caracters_codificats++;		//printf("Hem codificat %d caracters.",caracters_codificats);		//printf("Tancant fitxers...");		fclose (f_taula);		fclose (f_simbol);		fclose (f_control);		float RaoCompressioTeorica = (cont * 8) /( (caracters_codificats) * (log (10) / log (2)));		printf ("Rao de Compressio Teorica: %f\n",RaoCompressioTeorica);		fclose (f_out);		return 0;	}//////////////////////////////////////////////////////////////////////////////////////////////	int descodifica(char *argv[])	{		FILE *f_taula;		FILE *f_out;		FILE *f_control;		FILE *f_desc;		f_taula = fopen (argv[2], "r");		f_desc = fopen (argv[3], "r");		f_out = fopen (argv[4], "w");		f_control = fopen ("decode.txt","w");		int alt = 99999;		int baix = 0;		int valor=0;		int valor_prov;		char texto[10];		int num_caracteres;		int i;		/*Tractament de la taula de freqĂÂźencies*/		int v_taula[5];		fscanf (f_taula,"%d",&v_taula[0]);		i = 1;		while (!feof(f_taula))		{			fscanf (f_taula,"%d",&v_taula[i]);			i++;		}		/*Tractament del vector taula*/		int v_F [5];		//int v_P [5];		v_F [0]= v_taula [0];		printf("%d\n",v_F[0]);		for (i=1;i<5;i++)		{			v_F [i] = v_F [i-1] + v_taula [i];			printf("%d\n",v_F[i]);		}		int N = v_F [4];		fscanf(f_desc,"%s",texto);		if (strcmp (texto,"TI2005-06")==0)		{			fscanf(f_desc,"%d",&num_caracteres);			printf("el num de vueltas es: %d\n",num_caracteres);		}		//inicialitzem valor		valor_prov = getc(f_desc);//ens saltem el salt de linia		valor = 0;		for (i = 0; i<5 ; i++)		{			if ((valor_prov = getc(f_desc))!= -1)			{				valor = (valor*10)+(valor_prov -48);			}			else valor = (valor*10)+9;		}		printf("!!!!!!!!!!!!!!!!!!!!!!!!! ----------------> %d",valor);		for (i=0;i<num_caracteres;i++)		{		//Calculem el simbol de sortida//recalculem alt,baix i valor		calcularSimbol(&alt,&baix,&valor,N,v_F,f_control,f_out);		//treiem els digits iguals.		treureDigitsDescodificacio(&alt,&baix,&valor,f_control,f_desc);		}		fclose(f_desc);		fclose(f_control);		fclose(f_out);		fclose(f_taula);	return 0;	}////////////////////////////////////////////////////////////	int treureDigitsDescodificacio (int *al,int *ba,int *val,FILE *f_control,FILE *f_desc)	{		//procedemos a eliminar las cifras comunes		int cont=0;		int prob = 0;		while ((*al/10000) == (*ba/10000))		{			//fprintf(f_out,"%d",(*al/10000));			//printf("Afegirem %d al fitxer de sortida.\n",(*al/10000));			cont++;			*al = ((*al-((*al/10000)*10000))*10)+9;			*ba = ((*ba-((*ba/10000)*10000))*10);			if ((prob = getc(f_desc))!=-1)			{				*val = ((*val-((*val/10000)*10000))*10)+(prob-48);			}			else	*val = ((*val-((*val/10000)*10000))*10)+9;			fprintf(f_control,"El nou Alt es %d.\tEl nou Baix es %d.\t. Valor %d\n",*al,*ba,*val);		}		if(((*al/10000)-(*ba/10000))==1)//Calculem underflow del nombre resultant		{			int at,bt,vt;			int segundo_a=(*al-(*al/10000)*10000)/1000;			int segundo_b=(*ba-(*ba/10000)*10000)/1000;			int segundo_v=(*val-(*val/10000)*10000)/1000;			while(segundo_a == 0 && segundo_b == 9)			{				at=(*al-((*al/10000)*10000))-(segundo_a*1000);				bt=(*ba-((*ba/10000)*10000))-(segundo_b*1000);				vt=(*val-((*val/10000)*10000))-(segundo_v*1000);				*al=(((*al/10000)*10000)+at*10)+9;				*ba=((*ba/10000)*10000)+(bt*10);				*val=((*val/10000)*10000)+(vt*10);				if ((prob = getc(f_desc))!=-1)				{					*val =*val+(prob-48);				}				else	*val =*val+9;				segundo_a=(*al-(*al/10000)*10000)/1000;				segundo_b=(*ba-(*ba/10000)*10000)/1000;				segundo_v=(*val-(*val/10000)*10000)/1000;			}		}		return cont;	}////////////////////////////////////////////////////////////////////////////////	void calcularSimbol(int *al,int *ba,int *val,int N,int v_F[],FILE *f_control,FILE *f_out)	{		char simbol;		int rang = *al-*ba+1;		int i=0;		while( !(((*val-*ba+1)*v_F[4]) < (v_F[i]*rang)) )		{			i++;		}		if (i==0)simbol='a';		else if (i==1)simbol='e';		else if (i==2)simbol='i';		else if (i==3)simbol='o';		else if (i==4)simbol='u';		printf("------------%d",i);		fprintf (f_control,"Alt: %d, Baix: %d, Valor: %d,Simbol: %c.\n",*al,*ba,*val,simbol);		fprintf (f_out,"%c",simbol);		//actualitzem alt i baix		*al = (*ba + (rang * v_F[i])/ N)  -1;		if(i!=0) *ba = (*ba + (rang * v_F[i-1])/ N);	}

Oh... i almost forgot, it only works on Linux and Unix systems...

 

 

Notice from miCRoSCoPiC^eaRthLinG:

Once again, you lost a massive amount of credits, as you posted such a huge block of code without putting it in CODE or CODEBOX tags. Be VERY careful in future.

 

Reducing Hosting credits worth 30 days

Edited December 29, 2005 by miCRoSCoPiC^eaRthLinG (see edit history)

[jipman 0]

I can't see what we have to do with this, you haven't told us what compression algorithm you've applied, huffman probably?

Also, the comments are in some language !english, which 99% of the people around here won't get and there isn't enough comment.

Good luck with the comment translation!! (Catalan and Spanish...)

If you post a new topic with only code, at least proper (re)comment it so at least we can read it normally.

[Vyoma 0]

I even tried a using the Google Translator but I gave up.Anyway, it may be a bit of off topic, but do any of you guys have links or information on the algorithms used for compression. I have been rummaging over things and the net trying to get some information on the same.

[miCRoSCoPiC^eaRthLinG 0]

You might want to take a look at SharpZLib at http://www.icsharpcode.net/OpenSource/Sharib/Default.aspx

 

This isn't about alogorithms - but this site offers you a free opensource library that supports Zip, GZip, Tar and BZip2 compressions and is compatible with the .NET framework. It's meant to be used with C#.

 

Looking into the actual code might help you understand the various algorithms - and trying to implement and use them with your code will give you an even better understanding.

[PureHeart 0]

Anduril, why do you say the code works on *NIX* only. I think that an algorithm is Platform independent.

[jipman 0]

Probably because this is an implementation of that algorythm. But since noones is going to have use for this I'm closing this one up.