github.com/afumu/libc@v0.0.6/musl/src/ctype/isupper.c (about)

     1  #include <ctype.h>
     2  #undef isupper
     3  
     4  int isupper(int c)
     5  {
     6  	return (unsigned)c-'A' < 26;
     7  }
     8  
     9  int __isupper_l(int c, locale_t l)
    10  {
    11  	return isupper(c);
    12  }
    13  
    14  weak_alias(__isupper_l, isupper_l);