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/*
* strntoumax.c
*
* The strntoumax() function and associated
*/
#include <stddef.h>
#include <stdint.h>
#include <ctype.h>
static inline int digitval(int ch)
{
if (ch >= '0' && ch <= '9') {
return ch - '0';
} else if (ch >= 'A' && ch <= 'Z') {
return ch - 'A' + 10;
} else if (ch >= 'a' && ch <= 'z') {
return ch - 'a' + 10;
} else {
return -1;
}
}
uintmax_t strntoumax(const char *nptr, char **endptr, int base, size_t n)
{
int minus = 0;
uintmax_t v = 0;
int d;
while (n && isspace((unsigned char)*nptr)) {
nptr++;
n--;
}
/* Single optional + or - */
if (n && *nptr == '-') {
minus = 1;
nptr++;
n--;
} else if (n && *nptr == '+') {
nptr++;
}
if (base == 0) {
if (n >= 2 && nptr[0] == '0' && (nptr[1] == 'x' || nptr[1] == 'X')) {
n -= 2;
nptr += 2;
base = 16;
} else if (n >= 1 && nptr[0] == '0') {
n--;
nptr++;
base = 8;
} else {
base = 10;
}
} else if (base == 16) {
if (n >= 2 && nptr[0] == '0' && (nptr[1] == 'x' || nptr[1] == 'X')) {
n -= 2;
nptr += 2;
}
}
while (n && (d = digitval(*nptr)) >= 0 && d < base) {
v = v * base + d;
n--;
nptr++;
}
if (endptr)
*endptr = (char *)nptr;
return minus ? -v : v;
}
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