Even if you do not like or do not use most of the C standard library, that does not render it a liability. A good compiler, Keil among them, will only link in the functions that you actually call from your code; you do not pay for what you do not use. So, even if only 5% of the library appeals to you, it is an asset. Secondly, there are alternate implementations of a number of standard library functions for various derivatives; these varied implementations leverage the special features found in the derivatives they target. For example, Keil has a special version of memcmp() that benefits from the way dual data pointers are implemented in the DS89C4x0 for a performance benefit. While your own library of assembly functions might very well include something with the functionality of memcmp(), it probably does not include derivative-specific optimzations for the vast majority of devices on the market. I am quite content to leave the duties of writing things like this to the compiler makers, and enjoy knowing that when I invoke memcmp() from a properly built project, I have a good chance of executing a bug-free, nicely optimized version of it.

--Sasha Jevtic