Tasking VX assembler, using symbolic name instead of register name

Question

I am not a beginner programmer, but just started to use the Tasking VX assembler (manual http://www.tasking.com/support/tricore/tc_user_guide_v6.0.pdf). I cannot believe I am asking such a simple question, but after reading the Tasking VX assembler manual twice I cannot find an answer to the simplest of things: can I use a symbolic name instead of original register name?

Something like:

 loop_i = d3          ; d3 register, wishing to use symbolic name loop_i instead
                      ; (assembler doesn't allow the above definition)      
 mov16    loop_i, #4  ; this is what I want in the code
 mov16    d3, #4      ; this is what I must use instead

Thank you for forgiving me for an elementary question.

Answer 1

According to http://www.tasking.com/support/c166/c166_user_guide_v2.1.pdf TASKING VX-toolset for C166 User Guide, section "3.3. Operands of an Assembly Instruction", register operand should be of form defined in "3.5. Registers" section:

The following register names, either upper or lower case, should not be used for user-defined symbol names in an assembly language source file:

 R0 .. R15 (general purpose registers)
 RL0 .. RL7 (byte registers)
 RH0 .. RH7 (byte registers)

As I understand, user-defined symbols are for constants or labels; there is no user-defined symbol of type "register" in "3.7.4. Symbol Types and Expression Types". But you may try to use preprocessor with ".DEFINE":

  .DEFINE symbol string 

Description. With the .DEFINE directive you define a substitution string that you can use on all following source lines. The assembler searches all succeeding lines for an occurrence of symbol, and replaces it with string. If the symbol occurs in a double quoted string it is also replaced. Strings between single quotes are not expanded. This directive is useful for providing better documentation in the source program. A symbol can consist of letters, digits and underscore characters (_), and the first character cannot be a digit.

Try this:

 .define  loop_i  d3
 mov16    loop_i, #4

 mov16    d3, #4      ; this is what I must use instead

PS: http://www.tasking.com/support/tricore/tc_user_guide_v6.0.pdf "TASKING VX-toolset for TriCore User Guide" has similar assembler capabilities, so try .define. Only allowed set of register names is different from c166:

3.5. Registers The following register names, either uppercase or lowercase, should not be used for user-defined symbol names in an assembly language source file:

D0 .. D15 (data registers)
E0 .. E14 (data register pairs, only the even numbers)
A0 .. A15 (address registers)