diff options
Diffstat (limited to 'libc/stdlib/strtoimax.c')
| -rw-r--r-- | libc/stdlib/strtoimax.c | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/libc/stdlib/strtoimax.c b/libc/stdlib/strtoimax.c new file mode 100644 index 0000000..a742eb9 --- /dev/null +++ b/libc/stdlib/strtoimax.c @@ -0,0 +1,171 @@ +/* $OpenBSD: strtoimax.c,v 1.1 2006/01/13 17:58:09 millert Exp $ */ + +/*- + * Copyright (c) 1992 The Regents of the University of California. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <ctype.h> +#include <errno.h> +#include <inttypes.h> + +/* + * Convert a string to an intmax_t + * + * Ignores `locale' stuff. Assumes that the upper and lower case + * alphabets and digits are each contiguous. + */ +intmax_t +strtoimax(const char *nptr, char **endptr, int base) +{ + const char *s; + intmax_t acc, cutoff; + int c; + int neg, any, cutlim; + + /* + * Skip white space and pick up leading +/- sign if any. + * If base is 0, allow 0x for hex and 0 for octal, else + * assume decimal; if base is already 16, allow 0x. + */ + s = nptr; + do { + c = (unsigned char) *s++; + } while (isspace(c)); + if (c == '-') { + neg = 1; + c = *s++; + } else { + neg = 0; + if (c == '+') + c = *s++; + } + if ((base == 0 || base == 16) && + c == '0' && (*s == 'x' || *s == 'X')) { + c = s[1]; + s += 2; + base = 16; + } + if (base == 0) + base = c == '0' ? 8 : 10; + + /* + * Compute the cutoff value between legal numbers and illegal + * numbers. That is the largest legal value, divided by the + * base. An input number that is greater than this value, if + * followed by a legal input character, is too big. One that + * is equal to this value may be valid or not; the limit + * between valid and invalid numbers is then based on the last + * digit. For instance, if the range for intmax_t is + * [-9223372036854775808..9223372036854775807] and the input base + * is 10, cutoff will be set to 922337203685477580 and cutlim to + * either 7 (neg==0) or 8 (neg==1), meaning that if we have + * accumulated a value > 922337203685477580, or equal but the + * next digit is > 7 (or 8), the number is too big, and we will + * return a range error. + * + * Set any if any `digits' consumed; make it negative to indicate + * overflow. + */ + + /* BIONIC: avoid division and module for common cases */ +#define CASE_BASE(x) \ + case x: \ + if (neg) { \ + cutlim = INTMAX_MIN % x; \ + cutoff = INTMAX_MIN / x; \ + } else { \ + cutlim = INTMAX_MAX % x; \ + cutoff = INTMAX_MAX / x; \ + }; \ + break + + switch (base) { + case 4: + if (neg) { + cutlim = (int)(INTMAX_MIN % 4); + cutoff = INTMAX_MIN / 4; + } else { + cutlim = (int)(INTMAX_MAX % 4); + cutoff = INTMAX_MAX / 4; + } + break; + + CASE_BASE(8); + CASE_BASE(10); + CASE_BASE(16); + default: + cutoff = neg ? INTMAX_MIN : INTMAX_MAX; + cutlim = cutoff % base; + cutoff /= base; + } +#undef CASE_BASE + + if (neg) { + if (cutlim > 0) { + cutlim -= base; + cutoff += 1; + } + cutlim = -cutlim; + } + for (acc = 0, any = 0;; c = (unsigned char) *s++) { + if (isdigit(c)) + c -= '0'; + else if (isalpha(c)) + c -= isupper(c) ? 'A' - 10 : 'a' - 10; + else + break; + if (c >= base) + break; + if (any < 0) + continue; + if (neg) { + if (acc < cutoff || (acc == cutoff && c > cutlim)) { + any = -1; + acc = INTMAX_MIN; + errno = ERANGE; + } else { + any = 1; + acc *= base; + acc -= c; + } + } else { + if (acc > cutoff || (acc == cutoff && c > cutlim)) { + any = -1; + acc = INTMAX_MAX; + errno = ERANGE; + } else { + any = 1; + acc *= base; + acc += c; + } + } + } + if (endptr != 0) + *endptr = (char *) (any ? s - 1 : nptr); + return (acc); +} |