ack/lang/cem/libcc.ansi/core/stdlib/strtol.c
David Given d1cdb07719 Realise that the libc core can safely call other libc core functions, even if
they're not defined in the core: so putw() can call stdio stuff, for example.
So the earlier concept of pureness isn't necessary. Rename accordingly.
2018-06-21 23:24:23 +02:00

117 lines
2.2 KiB
C

/*
* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
* See the copyright notice in the ACK home directory, in the file "Copyright".
*/
/* $Id$ */
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <stdlib.h>
static unsigned long
string2long(register const char* nptr, char** endptr,
int base, int is_signed);
long int
strtol(register const char* nptr, char** endptr, int base)
{
return (signed long)string2long(nptr, endptr, base, 1);
}
unsigned long int
strtoul(register const char* nptr, char** endptr, int base)
{
return (unsigned long)string2long(nptr, endptr, base, 0);
}
static unsigned long
string2long(register const char* nptr, char** const endptr,
int base, int is_signed)
{
register unsigned int v;
register unsigned long val = 0;
register int c;
int ovfl = 0, sign = 1;
const char *startnptr = nptr, *nrstart;
if (endptr)
*endptr = (char*)nptr;
while (isspace(*nptr))
nptr++;
c = *nptr;
if (c == '-' || c == '+')
{
if (c == '-')
sign = -1;
nptr++;
}
nrstart = nptr; /* start of the number */
/* When base is 0, the syntax determines the actual base */
if (base == 0)
if (*nptr == '0')
if (*++nptr == 'x' || *nptr == 'X')
{
base = 16;
nptr++;
}
else
base = 8;
else
base = 10;
else if (base == 16 && *nptr == '0' && (*++nptr == 'x' || *nptr == 'X'))
nptr++;
while (isdigit(c = *nptr) || isalpha(c))
{
if (!ovfl)
{
if (isalpha(c))
v = 10 + (isupper(c) ? c - 'A' : c - 'a');
else
v = c - '0';
if (v >= base)
break;
if (val > (ULONG_MAX - v) / base)
++ovfl;
else
val = (val * base) + v;
}
nptr++;
}
if (endptr)
{
if (nrstart == nptr)
*endptr = (char*)startnptr;
else
*endptr = (char*)nptr;
}
if (!ovfl)
{
/* Overflow is only possible when converting a signed long.
* The "-(LONG_MIN+1)+(unsigned long) 1" construction is there
* to prevent overflow warnings on -LONG_MIN.
*/
if (is_signed
&& ((sign < 0 && val > -(LONG_MIN + 1) + (unsigned long)1)
|| (sign > 0 && val > LONG_MAX)))
ovfl++;
}
if (ovfl)
{
errno = ERANGE;
if (is_signed)
if (sign < 0)
return LONG_MIN;
else
return LONG_MAX;
else
return ULONG_MAX;
}
return (sign * val);
}