compact.c

/* compact.c - function to convert hex/octal/decimal/raw string to raw
 * ChangeLog since initial release in sendip 2.1.
 */
#include <stdio.h>
#include <string.h>

int compact_string(char *data_out) {
	char *data_in = data_out;
	int i=0;
	if(*data_in=='0') {
		data_in++;
		if(*data_in=='x' || *data_in=='X') {
			/* Hex */
			char c='\0';
			data_in++;
			while(*data_in) {
				if(*data_in>='0' && *data_in<='9') {
					c+=*data_in-'0';
				} else if(*data_in>='A' && *data_in<='F') {
					c+=*data_in-'A'+10;
				} else if(*data_in>='a' && *data_in<='f') {
					c+=*data_in-'a'+10;
				} else {
					fprintf(stderr,"Character %c invalid in hex data stream\n",
							  *data_in);
					return 0;
				}
				if( i&1) {
					*(data_out++)=c;  // odd nibble - output it
					c='\0';
				} else {
					c<<=4;   // even nibble - shift to top of byte
				}
				data_in++; i++;
			}
			*data_out=c; // make sure last nibble is added
			i++; i>>=1;  // i was a nibble count...
			return i;
		} else {
         /* Octal */
			char c='\0';
			while(*data_in) {
				if(*data_in>='0' && *data_in<='7') {
					c+=*data_in-'0';
				} else {
					fprintf(stderr,"Character %c invalid in octal data stream\n",
							  *data_in);
					return 0;
				}
				if( (i&3) == 3 ) {
					*(data_out++)=c;  // output every 4th char
					c='\0';
				} else {        // otherwise just shift it up
					c<<=2;
				}
				data_in++; i++;
			}
			*data_out=c;     // add partial last byte
			i+=3; i>>=2;
			return i;
		}
	} else {
		/* String */
		return strlen(data_in);
	}
}