If you know C, then the best "embedded C" book will be the manual that comes with the compiler you use. It will explain which C commands are available ([i]usually[/i] they follow K&R), and which (if any) extensions they implement. The compiler I use here at work has extensions such as BASEPAGE and loop(n). These are specific to the compiler I use, others will NOT have these additions.

Good Luck,
--Rich