C51: ?C? Library Routines

Information in this article applies to:

• C51 Version 6 and later

QUESTION

I've noticed that the C compiler generates lots of calls to routines that begin with ?C?. What are these routines?

ANSWER

The Keil C compiler uses "helper" routines to perform operations where in-line code would cause program bloat. These routines do things like fetch bytes or words from memory, dereference generic pointers, and so on. These routines are built into the C51 library files that are shipped with the product.

SEE ALSO

• C51: Function of ?C?ICALL and ?C?ICALL2
• C51: ?C? Load and Store Library Routines
• C51: ?C? Long/Float Math Library Routines
• C51: Use of F0 and F1 in PSW
• C51: Does the Run-time Library Disable Interrupts?
• C51: Stack Requirements of Run-Time Library Functions
• C51: re-use Library Functions from a Boot Application
• C51: Faster Integer Division

Last Reviewed: Thursday, February 25, 2021