Is there any way to declare a symbolic constant as 'an external number' in Keil C51 source code so that the compiler generates object file using instructions with # symbol prefix (e.g. mov r0,#symbol) and therefore the value of this symbol can be supplied on the linker level (from another obj file, where the symbol is given a value and declared as public) ? (Including file with #defines into the source code does not solve the issue - symbols must be defined at the compile time.) Note: in assembler it is easy ... file1.a51 : (file1.obj defines particular values of needed constants for a concrete project)
... public SYMBOL SYMBOL equ 5 ...
... extrn number (SYMBOL) ... mov a,#SYMBOL ...
I don't think so. Remember, the Linker deals with addresses - not values; but there might be a clue there...
Hi Andrew, "I don't think so..." - probably you are right (what a pity :-), I've thought it as well but I'm still not sure. In my opinion, the linker does not deal with addresses but with "numbers" associated with attributes - data(address), idata(address), xdata(address), ... and number. The attributes provide the linker with necessary information, so it can handle the numbers appropriately and can check their right use as well. If there is at least one assembler module with the equ directive used in a project, then you can find lines like:
VALUE TYPE NAME ------------------------------ N:0002H PUBLIC PADDRESS N:FF90H SYMBOL BFUX10000H
NAME ....... USAGE MODULE NAMES ---------------------------------------- ADST_NONE .. NUMB; REG3_30 BLNK_AD