Why are SFRs undefined in my assembly code?

If you want to use SFRs (Special Function Registers) in assembly code, you should always include a header files that defines the SFR symbols to use.

If writing separate assembly modules, SFR definitions will not automatically be accessible. The assembly header file <xc.inc> can be used to gain access to these register definitions

The symbols defined by these file do not have a leading underscore character, so you can use STATUS or PORTA, etc. Other symbols are defined for bits and which specify the register name and bit offset.

There may or may not be assembly-domain SFR symbols "left over" from the compilation process that you might be able to use in your assembly code, but you should not rely on these being present.
Always include the header files mentioned above so that you can guarantee that the symbols you require are defined.

Here is an example of a mid-range assembly module that uses SFRs.

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If you wish to access register definitions from assembly that is in-line with C code, ensure that the @xc.h@ header is included into the C module.

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