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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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