I am very confused about @ # * in addressing mode

Ssu-Han Huang

Dear,

Now, I am a rookie about assembly language, I have a problem while I read the code.
I am very confused about the @ # and * in addressing, even if I had read a lot about assembly language tool and some manual. There are many such syntax however can I never finda context about the usage and concept about @ # * clearly.

It really confused me, take a example

MOV [loc16],ARn

[loc16] = ARn;
If(loc16 = @ARn), then only the lower 16 bits of the selected auxiliary register
is modified. The upper 16 bits is unchanged.

The above is the statement.
The example is
MOV @AR4,AR3

; Load AR4 with the value in AR3.
; Upper 16 bits of XAR4 are
; unchanged.

Why not MOV AR4,AR3 ????
Because I had read that
MOV T,@VarA
before, I guess that all the CPU register are the same; however, I must be wrong.
I can't find a rule, please help me or give me a way to find the definition about them!

Thanks!!!
Maxwell :)

over 12 years ago

0 Igor Gorbachev over 12 years ago

Guru 20525 points

Hi,

A memory reference operand uses one of several memory addressing modes to refer to a location in
memory. For detailed explanation you can refer to the Chapter 5 of SPRU430E 7658.TI_TMS320C28x_CPU_Instruction_spru430e.pdf.

Regards,

Igor

0 Ssu-Han Huang over 12 years ago in reply to Igor Gorbachev

Prodigy 210 points

Thank you Igor,

I have read this chapter before, however there is only a little section with tiny word size about the usage of "@". ^^
This section tells that if @ before register, it is an optional syntax. I just want know more about the usage about what those symbols mean, such as *,*-XAR0, @, # and so on. It is hard for rookies like me that those syntax appears so frequently but without a detail description. :)

Best Regards,

Maxwell

C2000™︎ microcontrollers

C2000 microcontrollers forum

I am very confused about @ # * in addressing mode