/*#####################################################
###                                                 ###
###           HEXTEXT.C                             ###
###                                                 ###
###  author:  Adam ZIELINSKI                        ###
###           e0425671                              ###
###           a.zielinski@chello.at                 ###
###  date:    2006-11-14                            ###
###                                                 ###
#####################################################*/




#include <stdio.h>  /* for in-/output */
#include <stdlib.h> /* for EXIT_FAILURE */
#include <ctype.h>  /* for in-/output */
#include <math.h>  /* for in-/output */
#include <string.h>  /* for in-/output */
#include "hextext.h" /* just my header */


char *szCommand = "too early to tell...";


int main(int argc, char **argv){


	int i;
	int n;

	/*command used to start this program*/
	szCommand = argv[0];


	if (argc == 1){
		usage();
	}	

	for( i=1 ; i<argc; i++){
		if ( (n=un_base(argv[i],16)) != -1){

			printf("%c", n);

		} else {
			if (printf("\n%s: Illegal number %s", argv[0], argv[i]) < 0){
				(void) fprintf(stderr, "%s: Cannot print to stdout!\n", szCommand);
				exit (EXIT_FAILURE);					
			}		
		}
	}

	printf("\n");


		/*SUCCESS :D */
		return 0;
}


/*writes to stdout, how to use this prog*/
void usage(){
	(void) fprintf(stderr,"Usage: %s\n",szCommand);
	exit(EXIT_FAILURE);
}




int un_base(char *s, int b) {


	int i,j;
	int l = strlen( s );
	int r1;
	int r2;
	char base[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};


	r1 = 0;

	/* check each character in string s */
	for (i = 0; i < l; i++){

		r2 = r1;

		/* compare character with up to b chars from base */
		for ( j = 0; j < b ; j++){

			/* on match, increase r1 */
			if (s[i] == base[j]){
				r1 += (int)(j*pow(b, l-i-1));
				break;
			}
		}

		/* r1 has not changed and actual character is not '0' -> character out of range */
		if ( (r1==r2) && (s[i] != '0') ){
			return -1;
		}	
	}

	return r1;

}