cosmopolitan/libc/fmt/wcstoimax.c

70 lines
2.7 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/fmt/conv.h"
#include "libc/str/str.h"
intmax_t wcstoimax(const wchar_t *s, wchar_t **endptr, int base) {
intmax_t res = 0;
int neg = 0;
while (iswspace(*s)) {
s++;
}
switch (*s) {
case '-':
neg = 1;
/* fallthrough */
case '+':
s++;
break;
default:
break;
}
if (!base) {
if (*s == '0') {
s++;
if (*s == 'x' || *s == 'X') {
s++;
base = 16;
} else if (*s == 'b' || *s == 'B') {
s++;
base = 2;
} else {
base = 8;
}
} else {
base = 10;
}
}
for (;;) {
unsigned diglet = kBase36[*s];
if (!diglet || diglet > base) break;
s++;
res *= base; /* needs __muloti4() w/ clang */
res -= diglet - 1;
}
if (endptr) *endptr = (wchar_t *)s;
return neg ? res : -res;
}