ref: c11957a7915d355d80ff7e6a21721ba05441ca29 dir: /libkern/toupper.c/
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'); }