ref: c5c79d61e67f2c74a8d57eb1aeea87a23eeadd87
dir: /sys/src/ape/lib/ap/gen/toupper.c/
#include <ctype.h>
toupper(int c)
{
if(c < 'a' || c > 'z')
return c;
return (c-'a'+'A');
}
tolower(int c)
{
if(c < 'A' || c > 'Z')
return c;
return (c-'A'+'a');
}