CCSv6.1 linked list macro issue

I'm accustomed to link lists built out of dynamic memory (i.e. calls to malloc).  I've never seen a linked list like this one.  So, I need some more context to understand what you are doing.  

Supposing the macro did work, how do you invoke it in your main code?  Please describe the result of those macro invocations.  

Thanks and regards,

-George

Hi Georges,

in fact, as is, this piece of code is not very useful  ;o)

I reduced it to the minimum needed to understand the subject.

well, suppose you want to create a linked list of items numbered 1, 2, 3, and so on. Each of them keep a specific value.

At run time you walk through this list to retreive those specific values doing whatever you want and this list itself can grow (by adding items).

Suppose now you already knows the hundred first items, you would like to build the linked list at compile time to avoid lot of initialization code and lost time at run time.

It's normally very simple to acheive this goal using a macro with some parameters, like this one (pseudo code):

define          link                  0                    ; link = 0 mean you reach the end of linked list

SetItem        MACRO         num, value

                    dw                  num              ; set num in memory

                    dw                  value             ; set value in memory

$1:              dw                  link                 ; set actual value of link in memory

define        link                  $1                   ; set new value of link which pointed to this item so the following will be correctly linked

                 ENDMACRO

So, the last item is pointed to by the last (and actual) value of link

At compile time, for example, you can write something like:

                SetItem          1, 0x1546

                SetItem           2, 0x5486

....

                SetItem         100, 0x1234

At run time you know that item 100 is pointed to by link, the following piece of code walk through the linked list:

                mov.w           &link,R5           ; load R5 with link

                cmp.w          -2(R5), 0x5486 ; this item contain the value I'm searching ?

                je                  end_of_search  ; and R5 contain the good link @

               mov.w            @R5, R5         ; not the good item, so R5 is now the @ of following item, and so on

As you can see, it's very easy to manipulate such data structure, search item, read contents, and add item. Delete item

it's a bit more complicated.

Threaded virtual machine make an extensive use of this linked list.

Voilà !  ;o)

Well to return to my original question, how can I write the SetItem macro with CCSv6.1 ???!!!!

Regards,

Claude

claude caselles said:

how can I write the SetItem macro with CCSv6.1 ?

Please give this a try ...

;---------------------------------------------------------------------
; Init substitution symbols used in SetItem macro
;---------------------------------------------------------------------
		.asg	0, link0
		.asg	0, link_count
		.asg	0, label_count

;---------------------------------------------------------------------
; Define SetItem macro
;---------------------------------------------------------------------
SetItem		.macro	num, value
		.word	num
		.word	value
label:label_count:	.word	link:link_count:

		.eval	link_count+1,link_count
		.asg	label:label_count:, link:link_count:
		.eval	label_count+1, label_count

		.endm	

;---------------------------------------------------------------------
; Example usage of SetItem macro
;---------------------------------------------------------------------
		.sect	"linked_list_section"
		SetItem	1, 0x1546
		SetItem	2, 0x5486
		SetItem	3, 0x1234

;---------------------------------------------------------------------
; Code to start the traversal of the linked list
;---------------------------------------------------------------------
		.text
		.eval	label_count-1,label_count
		mov.w	&label:label_count:,R5

I can only hand verify this code, so I may have missed something.  But I'm confident it is close enough to get you started.

In particular, I am concerned that .word is not the best directive to use for reserving memory locations.  A better directive may be among those described in the section titled Directives that Initialize Values in the MSP430 assembly tools manual.  

A description of the directives in the macro is in the chapter titled Macro Language Description in that same manual.

Thanks and regards,

-George