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#include <stdlib.h>
#include <errno.h>
#include <limits.h>
#define UVLONG_MAX (1LL<<63)
unsigned long long
strtoull(char *nptr, char **endptr, int base)
{
char *p;
unsigned long long n, nn, m;
int c, ovfl, v, neg, ndig;
p = nptr;
neg = 0;
n = 0;
ndig = 0;
ovfl = 0;
/*
* White space
*/
for(;; p++) {
switch(*p) {
case ' ':
case '\t':
case '\n':
case '\f':
case '\r':
case '\v':
continue;
}
break;
}
/*
* Sign
*/
if(*p == '-' || *p == '+')
if(*p++ == '-')
neg = 1;
/*
* Base
*/
if(base == 0) {
base = 10;
if(*p == '0') {
base = 8;
if(p[1] == 'x' || p[1] == 'X'){
p += 2;
base = 16;
}
}
} else
if(base == 16 && *p == '0') {
if(p[1] == 'x' || p[1] == 'X')
p += 2;
} else
if(base < 0 || 36 < base)
goto Return;
/*
* Non-empty sequence of digits
*/
m = UVLONG_MAX/base;
for(;; p++,ndig++) {
c = *p;
v = base;
if('0' <= c && c <= '9')
v = c - '0';
else
if('a' <= c && c <= 'z')
v = c - 'a' + 10;
else
if('A' <= c && c <= 'Z')
v = c - 'A' + 10;
if(v >= base)
break;
if(n > m)
ovfl = 1;
nn = n*base + v;
if(nn < n)
ovfl = 1;
n = nn;
}
Return:
if(ndig == 0)
p = nptr;
if(endptr)
*endptr = p;
if(ovfl){
errno = ERANGE;
return UVLONG_MAX;
}
if(neg)
return -n;
return n;
}
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