ref: 3fe9730645df15f18689be26b842c06f60e40fae
dir: /sys/src/libc/port/toupper.c/
#include <ctype.h>
int
toupper(int c)
{
if(c < 'a' || c > 'z')
return c;
return _toupper(c);
}
int
tolower(int c)
{
if(c < 'A' || c > 'Z')
return c;
return _tolower(c);
}