src/user/ctype.nsh

/* ctype.nsc's shared helpers -- see ctype.nsc. */
i32 is_digit(u8 c);
i32 is_upper(u8 c);
i32 is_lower(u8 c);
i32 is_alpha(u8 c);
i32 is_alnum(u8 c);
i32 is_space(u8 c);
u8 to_upper(u8 c);
u8 to_lower(u8 c);