- for (; len-- && *s; s++) {
- if (!(*s == '0' || *s == '1')) {
- if (*s == '_' && len && *retlen
- && (s[1] == '0' || s[1] == '1'))
- {
- --len;
- ++s;
- }
- else if (seenb == FALSE && *s == 'b' && ruv == 0) {
- /* Disallow 0bbb0b0bbb... */
- seenb = TRUE;
- continue;
- }
- else {
- if (ckWARN(WARN_DIGIT))
- Perl_warner(aTHX_ WARN_DIGIT,
- "Illegal binary digit '%c' ignored", *s);
- break;
- }
- }
- if (!overflowed) {
- register UV xuv = ruv << 1;
-
- if ((xuv >> 1) != ruv) {
- overflowed = TRUE;
- rnv = (NV) ruv;
- if (ckWARN_d(WARN_OVERFLOW))
- Perl_warner(aTHX_ WARN_OVERFLOW,
- "Integer overflow in binary number");
- }
- else
- ruv = xuv | (*s - '0');
- }
- if (overflowed) {
- rnv *= 2;
+converts a string representing a binary number to numeric form.
+
+On entry I<start> and I<*len> give the string to scan, I<*flags> gives
+conversion flags, and I<result> should be NULL or a pointer to an NV.
+The scan stops at the end of the string, or the first invalid character.
+Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
+invalid character will also trigger a warning.
+On return I<*len> is set to the length of the scanned string,
+and I<*flags> gives output flags.
+
+If the value is <= C<UV_MAX> it is returned as a UV, the output flags are clear,
+and nothing is written to I<*result>. If the value is > UV_MAX C<grok_bin>
+returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
+and writes the value to I<*result> (or the value is discarded if I<result>
+is NULL).
+
+The binary number may optionally be prefixed with "0b" or "b" unless
+C<PERL_SCAN_DISALLOW_PREFIX> is set in I<*flags> on entry. If
+C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the binary
+number may use '_' characters to separate digits.
+
+=cut
+ */
+
+UV
+Perl_grok_bin(pTHX_ const char *start, STRLEN *len_p, I32 *flags, NV *result) {
+ const char *s = start;
+ STRLEN len = *len_p;
+ UV value = 0;
+ NV value_nv = 0;
+
+ const UV max_div_2 = UV_MAX / 2;
+ const bool allow_underscores = *flags & PERL_SCAN_ALLOW_UNDERSCORES;
+ bool overflowed = FALSE;
+ char bit;
+
+ if (!(*flags & PERL_SCAN_DISALLOW_PREFIX)) {
+ /* strip off leading b or 0b.
+ for compatibility silently suffer "b" and "0b" as valid binary
+ numbers. */
+ if (len >= 1) {
+ if (s[0] == 'b') {
+ s++;
+ len--;
+ }
+ else if (len >= 2 && s[0] == '0' && s[1] == 'b') {
+ s+=2;
+ len-=2;
+ }
+ }
+ }
+
+ for (; len-- && (bit = *s); s++) {
+ if (bit == '0' || bit == '1') {
+ /* Write it in this wonky order with a goto to attempt to get the
+ compiler to make the common case integer-only loop pretty tight.
+ With gcc seems to be much straighter code than old scan_bin. */
+ redo:
+ if (!overflowed) {
+ if (value <= max_div_2) {
+ value = (value << 1) | (bit - '0');
+ continue;
+ }
+ /* Bah. We're just overflowed. */
+ if (ckWARN_d(WARN_OVERFLOW))
+ Perl_warner(aTHX_ packWARN(WARN_OVERFLOW),
+ "Integer overflow in binary number");
+ overflowed = TRUE;
+ value_nv = (NV) value;
+ }
+ value_nv *= 2.0;