| 0,0 → 1,91 |
|---|
| /* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */ |
| #include <limits.h> |
| #include <ctype.h> |
| #include <errno.h> |
| #include <stdlib.h> |
| #include <libc/unconst.h> |
| |
| long |
| strtol(const char *nptr, char **endptr, int base) |
| { |
| const char *s = nptr; |
| unsigned long acc; |
| int c; |
| unsigned long cutoff; |
| int neg = 0, 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. |
| */ |
| do { |
| c = *s++; |
| } while (isspace(c)); |
| if (c == '-') |
| { |
| neg = 1; |
| c = *s++; |
| } |
| else 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 longs is |
| * [-2147483648..2147483647] and the input base is 10, |
| * cutoff will be set to 214748364 and cutlim to either |
| * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated |
| * a value > 214748364, 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. |
| */ |
| cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX; |
| cutlim = cutoff % (unsigned long)base; |
| cutoff /= (unsigned long)base; |
| for (acc = 0, any = 0;; c = *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 || acc > cutoff || (acc == cutoff && c > cutlim)) |
| any = -1; |
| else |
| { |
| any = 1; |
| acc *= base; |
| acc += c; |
| } |
| } |
| if (any < 0) |
| { |
| acc = neg ? LONG_MIN : LONG_MAX; |
| errno = ERANGE; |
| } |
| else if (neg) |
| acc = -acc; |
| if (endptr != 0) |
| *endptr = any ? unconst(s, char *) - 1 : unconst(nptr, char *); |
| return acc; |
| } |