fusl/src/ctype/isupper.c

#include <ctype.h>
#include "libc.h"
#undef isupper

int isupper(int c) {
  return (unsigned)c - 'A' < 26;
}

int __isupper_l(int c, locale_t l) {
  return isupper(c);
}

weak_alias(__isupper_l, isupper_l);