ARM Program counter error

I have this line in my code :


It gives an error :
warning: A1608W: MOV pc,<rn> instruction used, but BX <rn> is preferred
So i change it to :



It gave this :

error: A1647E: Bad register name symbol, expected Integer register

help please

kmegamind said:

Code:

MOV  PC, r14

It gives an error :
warning: A1608W: MOV pc,<rn> instruction used, but BX <rn> is preferred

Click to expand...

First of all, it was a warning, not an error message, there is a significant difference.

During compilation or assembly, an error will usually prevent completion, while a warning will not.

The warning alerts the programmer as to a possible issue or in this case, the use of a deprecated/improper syntax and may suggest a more acceptable method.

The following line of assembly:


Indicates moving the contents of r14, the next address, into the Program Counter (PC), which the Assembler views as equivalent to the Branch and Exchange (BX) instruction:

kmegamind said:

So i change it to :

Code:

MOV  BX, r14

It gave this :

error: A1647E: Bad register name symbol, expected Integer register

Click to expand...

In this case, incorrect syntax caused the issuance of an error.

As the following line:


Incorrectly combines two operations/instructions, which is why the Assembler complained about expecting an integer register and instead you gave it another instruction (BX).

The correct syntax would have been:


What exactly are you attempting to accomplish with the following line?


I'm not sure it would yield the expected results.

Until you are quite familiar with ARM assembly, I suggest you refrain from referencing r13, r14 and r15 as these registers can and do have special purpose.



BigDog

Thank you for this explanation.
i am just starting to learn ARM so i am running the example programs i find in the book i am learning from
So when i run this code:

i get the warning i mentioned and the following two errors :

testing.axf: Error: L6320W: Ignoring --entry command. Cannot find argument 'Reset_Handler'.
testing.axf: Warning: L6320W: Ignoring --first command. Cannot find argument '__Vectors'.


I couldn't find any help regarding those two errors so i thought the PC warning thing caused the assembler to stop building or something.
May you help me with these errors ?