/* @file:   asciibin.c
   @author: Matt Bradford
   @date:   16 Aug 2005
   @desc:   encodes and decodes strings to a binary representation and back.
*/

#include <stdio.h>
#include <stdlib.h>

#ifndef ONE_CHAR
#define ONE_CHAR '='
#endif
#ifndef ZERO_CHAR
#define ZERO_CHAR '-'
#endif

/* Given an integer , will print out the binary representation
   of that character using ONE_CHAR and ZERO_CHAR */
void printBinString(int x) {
int n;
   for(n=0; n<8; n++) {
      if((x & 0x80) !=0) {
         printf("%c",ONE_CHAR);
      } else {
         printf("%c",ZERO_CHAR);
      } 
      x = x<<1;
   }
};

/* Encode a string. 
   If not quoted, spaces will be inserted automatically
   between parameters. */
int encode(int argc, char *argv[]) {
	/* n holds the position in the current byte */
	int i,j,n;
	/* x is the current character being translated */
	char x;
        for (i=2; i<argc; i++) {
		j=0;
		while (argv[i][j] != '\0') 
			printBinString(argv[i][j++]);
		if (i<argc-1)
			printBinString(' ');
	};
	fflush(stdout);
	printf("\n");
	return 0;
}

/* Eecode a string.
   No effort is made to cater for spaces or foreign
   characters. */
int decode(int argc, char *argv[]) {
	int i,j,n;
	/* Val holds the ascii value */
    	/* N holds our current position in the byte */
	char val;
	n=0,val=0;
        for (i=2; i<argc; i++) {
		j=0;
		while (argv[i][j] != '\0') {
			/* Add a one to value if it's a one symbol */
			val+=(argv[i][j]==ONE_CHAR);
			n++;
			if (n==8) { /* end of byte? print and reset */
				printf("%c", val);
				val=0; n=0;
			} else { /* Shift bits left if not at end */
				val=val<<1;
			}
			j++;
		};
	};
	printf("\n");
	return 0;
}

/* Show help and exit. */
void showhelp(char *progname) {
	printf("Ascii to Binary Translator\n");
	printf("by Matt Bradford, 2005.\n\n");
	printf("Usage: \n\n");
	printf("%s -d [string containing %c and %c ]\n",progname,ONE_CHAR,ZERO_CHAR);
	printf("%s -e string1 string2 string3\n",progname);
	printf("\nSwitches:\n");
	printf("\t-d\tDecode a string.\n");
	printf("\t-e\tEncode strings.\n\n");
	exit(EXIT_FAILURE);
};

/* Parses parameters.
   Calls help (which exits) if parameters aren't right.
   returns 1 for encrypt, 0 for decrypt.  */ 
int params(int argc, char *argv[]) {
	int retval=-1;
	if (argc <= 1) showhelp(argv[0]);
	if (strcmp(argv[1],"-d") == 0) retval=0;
	if (strcmp(argv[1],"-e") == 0) retval=1;
	if (retval == -1) showhelp(argv[0]);
	return retval;
};

/* Main Program */
int main(int argc, char *argv[]) {
	int enc;
	if (params(argc,argv)) { /* Encrypt */
		encode(argc, argv);
	} else { /* decrypt */
		decode(argc, argv);
	}
	return 0;
};