#define TOK_REM tok_decl(10,2)
/* For now all unary operators have the same precedence, and that's used to
- * identify them as unary operators
- */
+ * identify them as unary operators */
#define UNARYPREC 14
#define TOK_BNOT tok_decl(UNARYPREC,0)
#define TOK_NOT tok_decl(UNARYPREC,1)
/* "applying" a token means performing it on the top elements on the integer
* stack. For a unary operator it will only change the top element, but a
- * binary operator will pop two arguments and push a result
- */
+ * binary operator will pop two arguments and push a result */
static short arith_apply(operator op, long *numstack, long **numstackptr)
{
long numptr_val;
long *NUMPTR_M1;
- /* There is no operator that can work without arguments */
- if (NUMPTR == numstack) {
- goto err;
- }
-
+ if (NUMPTR == numstack) goto err; /* There is no operator that can work
+ without arguments */
NUMPTR_M1 = NUMPTR - 1;
- if (op == TOK_UMINUS) {
+ if (op == TOK_UMINUS)
*NUMPTR_M1 *= -1;
- } else if (op == TOK_NOT) {
+ else if (op == TOK_NOT)
*NUMPTR_M1 = !(*NUMPTR_M1);
- } else if (op == TOK_BNOT) {
+ else if (op == TOK_BNOT)
*NUMPTR_M1 = ~(*NUMPTR_M1);
- } else if (op != TOK_UPLUS) {
+ else if (op != TOK_UPLUS) {
/* Binary operators */
-
- /* ... and binary operators need two arguments */
- if (NUMPTR_M1 == numstack) {
- goto err;
- }
- /* ... and they pop one */
- numptr_val = *--NUMPTR;
-
+ if (NUMPTR_M1 == numstack) goto err; /* ... and binary operators need two
+ arguments */
+ numptr_val = *--NUMPTR; /* ... and they pop one */
NUMPTR_M1 = NUMPTR - 1;
-
- if (op == TOK_BOR) {
+ if (op == TOK_BOR)
*NUMPTR_M1 |= numptr_val;
- } else if (op == TOK_OR) {
+ else if (op == TOK_OR)
*NUMPTR_M1 = numptr_val || *NUMPTR_M1;
- } else if (op == TOK_BAND) {
+ else if (op == TOK_BAND)
*NUMPTR_M1 &= numptr_val;
- } else if (op == TOK_AND) {
+ else if (op == TOK_AND)
*NUMPTR_M1 = *NUMPTR_M1 && numptr_val;
- } else if (op == TOK_EQ) {
+ else if (op == TOK_EQ)
*NUMPTR_M1 = (*NUMPTR_M1 == numptr_val);
- } else if (op == TOK_NE) {
+ else if (op == TOK_NE)
*NUMPTR_M1 = (*NUMPTR_M1 != numptr_val);
- } else if (op == TOK_GE) {
+ else if (op == TOK_GE)
*NUMPTR_M1 = (*NUMPTR_M1 >= numptr_val);
- } else if (op == TOK_RSHIFT) {
+ else if (op == TOK_RSHIFT)
*NUMPTR_M1 >>= numptr_val;
- } else if (op == TOK_LSHIFT) {
+ else if (op == TOK_LSHIFT)
*NUMPTR_M1 <<= numptr_val;
- } else if (op == TOK_GT) {
+ else if (op == TOK_GT)
*NUMPTR_M1 = (*NUMPTR_M1 > numptr_val);
- } else if (op == TOK_LT) {
+ else if (op == TOK_LT)
*NUMPTR_M1 = (*NUMPTR_M1 < numptr_val);
- } else if (op == TOK_LE) {
+ else if (op == TOK_LE)
*NUMPTR_M1 = (*NUMPTR_M1 <= numptr_val);
- } else if (op == TOK_MUL) {
+ else if (op == TOK_MUL)
*NUMPTR_M1 *= numptr_val;
- } else if (op == TOK_ADD) {
+ else if (op == TOK_ADD)
*NUMPTR_M1 += numptr_val;
- } else if (op == TOK_SUB) {
+ else if (op == TOK_SUB)
*NUMPTR_M1 -= numptr_val;
- }
- /* zero divisor check */
- else if (numptr_val == 0) {
+ else if(numptr_val==0) /* zero divisor check */
return -2;
- } else if (op == TOK_DIV) {
+ else if (op == TOK_DIV)
*NUMPTR_M1 /= numptr_val;
- } else if (op == TOK_REM) {
+ else if (op == TOK_REM)
*NUMPTR_M1 %= numptr_val;
- }
/* WARNING!!! WARNING!!! WARNING!!! */
/* Any new operators should be added BEFORE the zero divisor check! */
}
return 0;
- err:
- return (-1);
+err: return(-1);
}
static const char endexpression[] = ")";
static const char op_token[] = {
/* paired with equal */
TOK_NE, TOK_LE, TOK_GE,
- /* paired with self -- note: ! is special-cased below */
+ /* paired with self -- note: ! is special-cased below*/
TOK_ERROR, TOK_LSHIFT, TOK_RSHIFT, TOK_EQ, TOK_OR, TOK_AND,
/* singles */
TOK_NOT, TOK_LT, TOK_GT, TOK_ERROR, TOK_BOR, TOK_BAND,
#define NUM_PAIR_EQUAL 3
#define NUM_PAIR_SAME 6
-extern long arith(const char *expr, int *errcode)
+extern long arith (const char *expr, int *errcode)
{
register char arithval; /* Current character under analysis */
operator lasttok, op;
unsigned char prec;
+
const char *p = endexpression;
- size_t datasizes = strlen(expr);
+
+ size_t datasizes = strlen(expr) + 2;
/* Stack of integers */
/* The proof that there can be no more than strlen(startbuf)/2+1 integers
* in any given correct or incorrect expression is left as an excersize to
* the reader. */
- long *numstack = alloca(((datasizes + 1) / 2) * sizeof(long));
- long *numstackptr = numstack;
-
+ long *numstack = alloca(((datasizes)/2)*sizeof(long)),
+ *numstackptr = numstack;
/* Stack of operator tokens */
- operator * stack = alloca((datasizes + 1) * sizeof(operator));
- operator * stackptr = stack;
+ operator *stack = alloca((datasizes) * sizeof(operator)),
+ *stackptr = stack;
- /* start off with a left paren */
- *stackptr++ = lasttok = TOK_LPAREN;
+ *numstack = 0;
+ *stackptr++ = lasttok = TOK_LPAREN; /* start off with a left paren */
loop:
if ((arithval = *expr) == 0) {
- /* Null expression. */
- if (p == endexpression) {
- return (*errcode = 0);
+ if (p == endexpression) { /* Null expression. */
+ *errcode = 0;
+ return *numstack;
}
/* This is only reached after all tokens have been extracted from the
goto loop; /* and let the loop process it. */
}
/* At this point, we're done with the expression. */
- if (numstackptr != numstack + 1) { /* ... but if there isn't, it's bad */
+ if (numstackptr != numstack+1) {/* ... but if there isn't, it's bad */
err:
return (*errcode = -1);
/* NOTREACHED */
return *numstack;
} else {
/* Continue processing the expression. */
- /* Skip whitespace */
if (isspace(arithval)) {
- goto prologue;
+ goto prologue; /* Skip whitespace */
}
- /* isdigit ? */
- if ((unsigned) arithval - '0' <= 9) {
+ if ((unsigned)arithval-'0' <= 9) /* isdigit */ {
*numstackptr++ = strtol(expr, (char **) &expr, 10);
lasttok = TOK_NUM;
goto loop;
goto err;
}
#else
- for (p = op_char; *p != arithval; p++) {
+ for ( p=op_char ; *p != arithval ; p++ ) {
if (!*p) {
goto err;
}
}
#endif
- p = op_token + (int) (p - op_char);
+ p = op_token + (int)(p - op_char);
++expr;
if ((p >= op_token + NUM_PAIR_EQUAL) || (*expr != '=')) {
p += NUM_PAIR_EQUAL;
if ((p >= op_token + NUM_PAIR_SAME + NUM_PAIR_EQUAL)
|| (*expr != arithval) || (arithval == '!')) {
--expr;
- /* single = */
- if (arithval == '=') {
+ if (arithval == '=') { /* single = */
goto err;
}
p += NUM_PAIR_SAME;
* a number, since it evaluates to one). Think about it.
* It makes sense. */
if ((lasttok != TOK_NUM)
- && (p >=
- (op_token + NUM_PAIR_SAME + NUM_PAIR_EQUAL +
- sizeof(op_char) - 2))) {
- /* Unary plus or minus */
- p += 2;
+ && (p >= op_token + NUM_PAIR_SAME + NUM_PAIR_EQUAL
+ + sizeof(op_char) - 2)) {
+ p += 2; /* Unary plus or minus */
}
}
}
/* Left paren is given the lowest priority so it will never be
* "applied" in this way */
prec = PREC(op);
-
- /* not left paren or unary */
- if ((prec > 0) && (prec != UNARYPREC)) {
- /* binary op must be preceded by a num */
- if (lasttok != TOK_NUM) {
+ if ((prec > 0) && (prec != UNARYPREC)) { /* not left paren or unary */
+ if (lasttok != TOK_NUM) { /* binary op must be preceded by a num */
goto err;
}
while (stackptr != stack) {
* tokens and apply them */
if (stackptr[-1] == TOK_LPAREN) {
--stackptr;
-
- /* Any operator directly after a */
- lasttok = TOK_NUM;
-
+ lasttok = TOK_NUM; /* Any operator directly after a */
/* close paren should consider itself binary */
goto prologue;
}
break;
}
*errcode = ARITH_APPLY(*--stackptr);
- if (*errcode) {
- return *errcode;
- }
+ if(*errcode) return *errcode;
}
if (op == TOK_RPAREN) {
goto err;
projects / oweals / busybox.git / blobdiff