ref: aa4cf3a4b23b4a06b2c67c18957f0574aa37df8b 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'); }