int main(void)
{
char bst[CHAR_BIT*sizeof(int)+1] = {0};
printf("Enter a binary string: ");
while(scanf("%s", bst)==1){
printf("Binary \"%s\" is %d in decimal notation.\n",
bst, abtoi(bst));
printf("\nPlease enter another binary string (EOF to quit): ");
}
return 0;
}
/*
* recursive expression parser
*
* Input: pointer to argument rest string
*
* Output: computed value
*/
int eval(char *s)
{
register char *p;
register int val;
char word[MAXLINE];
struct sym *sp;
val = 0;
while (*s) {
p = word;
if (*s == '(') {
s++;
while (*s != ')') {
if (*s == '\0') {
asmerr(E_MISPAR);
goto eval_break;
}
*p++ = *s++;
}
*p = '\0';
s++;
val = eval(word);
continue;
}
if (*s == STRSEP) {
s++;
while (*s != STRSEP) {
if (*s == '\n' || *s == '\0') {
asmerr(E_MISHYP);
goto hyp_error;
}
*p++ = *s++;
}
s++;
hyp_error:
*p = '\0';
val = strval(word);
continue;
}
if (isari(*s))
*p++ = *s++;
else
while (!isspace(*s) && !isari(*s) && (*s != '\0'))
*p++ = *s++;
*p = '\0';
switch (get_type(word)) {
case OPESYM: /* symbol */
if (strcmp(word, "$") == 0) {
val = pc;
break;
}
if (strlen(word) > SYMSIZE)
word[SYMSIZE] = '\0';
if ((sp = get_sym(word)) != NULL)
val = sp->sym_val;
else
asmerr(E_UNDSYM);
break;
case OPEDEC: /* decimal number */
val = atoi(word);
break;
case OPEHEX: /* hexadecimal number */
val = axtoi(word);
break;
case OPEBIN: /* binary number */
val = abtoi(word);
break;
case OPEOCT: /* octal number */
val = aotoi(word);
break;
case OPESUB: /* arithmetical - */
val -= eval(s);
goto eval_break;
case OPEADD: /* arithmetical + */
val += eval(s);
goto eval_break;
case OPEMUL: /* arithmetical * */
val *= eval(s);
goto eval_break;
case OPEDIV: /* arithmetical / */
val /= eval(s);
goto eval_break;
case OPEMOD: /* arithmetical modulo */
val %= eval(s);
goto eval_break;
case OPESHL: /* logical shift left */
val <<= eval(s);
goto eval_break;
case OPESHR: /* logical shift right */
val >>= eval(s);
goto eval_break;
case OPELOR: /* logical OR */
val |= eval(s);
goto eval_break;
case OPELAN: /* logical AND */
val &= eval(s);
goto eval_break;
case OPEXOR: /* logical XOR */
val ^= eval(s);
goto eval_break;
case OPECOM: /* logical complement */
val = ~(eval(s));
goto eval_break;
}
}
eval_break:
return(val);
}
