https://github.com/python/cpython
Tip revision: 1da43e5e916949c8e849e656d9d05fa4b9d6836c authored by Benjamin Peterson on 26 June 2009, 13:21:52 UTC
rearrange the sections of the README, so they'll hopefully be more in the order people will interested in
rearrange the sections of the README, so they'll hopefully be more in the order people will interested in
Tip revision: 1da43e5
mystrtoul.c
#include "Python.h"
#if defined(__sgi) && defined(WITH_THREAD) && !defined(_SGI_MP_SOURCE)
#define _SGI_MP_SOURCE
#endif
/* strtol and strtoul, renamed to avoid conflicts */
#include <ctype.h>
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
/* Static overflow check values for bases 2 through 36.
* smallmax[base] is the largest unsigned long i such that
* i * base doesn't overflow unsigned long.
*/
static unsigned long smallmax[] = {
0, /* bases 0 and 1 are invalid */
0,
ULONG_MAX / 2,
ULONG_MAX / 3,
ULONG_MAX / 4,
ULONG_MAX / 5,
ULONG_MAX / 6,
ULONG_MAX / 7,
ULONG_MAX / 8,
ULONG_MAX / 9,
ULONG_MAX / 10,
ULONG_MAX / 11,
ULONG_MAX / 12,
ULONG_MAX / 13,
ULONG_MAX / 14,
ULONG_MAX / 15,
ULONG_MAX / 16,
ULONG_MAX / 17,
ULONG_MAX / 18,
ULONG_MAX / 19,
ULONG_MAX / 20,
ULONG_MAX / 21,
ULONG_MAX / 22,
ULONG_MAX / 23,
ULONG_MAX / 24,
ULONG_MAX / 25,
ULONG_MAX / 26,
ULONG_MAX / 27,
ULONG_MAX / 28,
ULONG_MAX / 29,
ULONG_MAX / 30,
ULONG_MAX / 31,
ULONG_MAX / 32,
ULONG_MAX / 33,
ULONG_MAX / 34,
ULONG_MAX / 35,
ULONG_MAX / 36,
};
/* maximum digits that can't ever overflow for bases 2 through 36,
* calculated by [int(math.floor(math.log(2**32, i))) for i in range(2, 37)].
* Note that this is pessimistic if sizeof(long) > 4.
*/
#if SIZEOF_LONG == 4
static int digitlimit[] = {
0, 0, 32, 20, 16, 13, 12, 11, 10, 10, /* 0 - 9 */
9, 9, 8, 8, 8, 8, 8, 7, 7, 7, /* 10 - 19 */
7, 7, 7, 7, 6, 6, 6, 6, 6, 6, /* 20 - 29 */
6, 6, 6, 6, 6, 6, 6}; /* 30 - 36 */
#elif SIZEOF_LONG == 8
/* [int(math.floor(math.log(2**64, i))) for i in range(2, 37)] */
static int digitlimit[] = {
0, 0, 64, 40, 32, 27, 24, 22, 21, 20, /* 0 - 9 */
19, 18, 17, 17, 16, 16, 16, 15, 15, 15, /* 10 - 19 */
14, 14, 14, 14, 13, 13, 13, 13, 13, 13, /* 20 - 29 */
13, 12, 12, 12, 12, 12, 12}; /* 30 - 36 */
#else
#error "Need table for SIZEOF_LONG"
#endif
/*
** strtoul
** This is a general purpose routine for converting
** an ascii string to an integer in an arbitrary base.
** Leading white space is ignored. If 'base' is zero
** it looks for a leading 0b, 0o or 0x to tell which
** base. If these are absent it defaults to 10.
** Base must be 0 or between 2 and 36 (inclusive).
** If 'ptr' is non-NULL it will contain a pointer to
** the end of the scan.
** Errors due to bad pointers will probably result in
** exceptions - we don't check for them.
*/
unsigned long
PyOS_strtoul(register char *str, char **ptr, int base)
{
register unsigned long result = 0; /* return value of the function */
register int c; /* current input character */
register int ovlimit; /* required digits to overflow */
/* skip leading white space */
while (*str && isspace(Py_CHARMASK(*str)))
++str;
/* check for leading 0b, 0o or 0x for auto-base or base 16 */
switch (base) {
case 0: /* look for leading 0b, 0o or 0x */
if (*str == '0') {
++str;
if (*str == 'x' || *str == 'X') {
/* there must be at least one digit after 0x */
if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 16) {
if (ptr)
*ptr = str;
return 0;
}
++str;
base = 16;
} else if (*str == 'o' || *str == 'O') {
/* there must be at least one digit after 0o */
if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 8) {
if (ptr)
*ptr = str;
return 0;
}
++str;
base = 8;
} else if (*str == 'b' || *str == 'B') {
/* there must be at least one digit after 0b */
if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 2) {
if (ptr)
*ptr = str;
return 0;
}
++str;
base = 2;
} else {
/* skip all zeroes... */
while (*str == '0')
++str;
while (isspace(Py_CHARMASK(*str)))
++str;
if (ptr)
*ptr = str;
return 0;
}
}
else
base = 10;
break;
/* even with explicit base, skip leading 0? prefix */
case 16:
if (*str == '0') {
++str;
if (*str == 'x' || *str == 'X') {
/* there must be at least one digit after 0x */
if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 16) {
if (ptr)
*ptr = str;
return 0;
}
++str;
}
}
break;
case 8:
if (*str == '0') {
++str;
if (*str == 'o' || *str == 'O') {
/* there must be at least one digit after 0o */
if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 8) {
if (ptr)
*ptr = str;
return 0;
}
++str;
}
}
break;
case 2:
if(*str == '0') {
++str;
if (*str == 'b' || *str == 'B') {
/* there must be at least one digit after 0b */
if (_PyLong_DigitValue[Py_CHARMASK(str[1])] >= 2) {
if (ptr)
*ptr = str;
return 0;
}
++str;
}
}
break;
}
/* catch silly bases */
if (base < 2 || base > 36) {
if (ptr)
*ptr = str;
return 0;
}
/* skip leading zeroes */
while (*str == '0')
++str;
/* base is guaranteed to be in [2, 36] at this point */
ovlimit = digitlimit[base];
/* do the conversion until non-digit character encountered */
while ((c = _PyLong_DigitValue[Py_CHARMASK(*str)]) < base) {
if (ovlimit > 0) /* no overflow check required */
result = result * base + c;
else { /* requires overflow check */
register unsigned long temp_result;
if (ovlimit < 0) /* guaranteed overflow */
goto overflowed;
/* there could be an overflow */
/* check overflow just from shifting */
if (result > smallmax[base])
goto overflowed;
result *= base;
/* check overflow from the digit's value */
temp_result = result + c;
if (temp_result < result)
goto overflowed;
result = temp_result;
}
++str;
--ovlimit;
}
/* set pointer to point to the last character scanned */
if (ptr)
*ptr = str;
return result;
overflowed:
if (ptr) {
/* spool through remaining digit characters */
while (_PyLong_DigitValue[Py_CHARMASK(*str)] < base)
++str;
*ptr = str;
}
errno = ERANGE;
return (unsigned long)-1;
}
/* Checking for overflow in PyOS_strtol is a PITA; see comments
* about PY_ABS_LONG_MIN in longobject.c.
*/
#define PY_ABS_LONG_MIN (0-(unsigned long)LONG_MIN)
long
PyOS_strtol(char *str, char **ptr, int base)
{
long result;
unsigned long uresult;
char sign;
while (*str && isspace(Py_CHARMASK(*str)))
str++;
sign = *str;
if (sign == '+' || sign == '-')
str++;
uresult = PyOS_strtoul(str, ptr, base);
if (uresult <= (unsigned long)LONG_MAX) {
result = (long)uresult;
if (sign == '-')
result = -result;
}
else if (sign == '-' && uresult == PY_ABS_LONG_MIN) {
result = LONG_MIN;
}
else {
errno = ERANGE;
result = LONG_MAX;
}
return result;
}