[Coco] Optimizing 6809 Assembly Code: Part 2 – Speedup Storing Data – Unrolling Loops

[Brett Gordon]

This is how literals (string,number,etc) are done in forth!

: slit  ( -- a ) \ string literal runtime.
pull dup dup @ + push ;

So:

" Hello World!"

Compiles to this:

<slit> <12><H><e><l>...<next op>

: type  ( a -- ) \ print string
dup cell+ swap @ for c at + emit next drop ;

Who needs registers anyway? :)



On Sep 15, 2017 11:07 PM, "Dave Philipsen" <dave at davebiz.com> wrote:
>
> Here's a little trick you could add to your blog.  I think I posted an
example of this before.  I don't know that it necessarily optimizes for
speed but it saves space. When printing a string or any kind of calling a
subroutine which requires a string, instead of pointing to the string and
then calling the subroutine like this:
>
> ldx   #strptr         point to the string
> jsr   prtstr          print the string
> lda   #??             continue with the rest of the program
>
> You can do this:
>
> jsr   prtstr          call the print string subroutine which pulls the
address of the string from the
> fcs   /text string/   program counter which was just pushed to the stack
> lda   #?? continue with the rest of the program
>
> The prtstr routine can change the program counter as it is saved on the
stack so that when the routine returns, it returns to the point just past
the end of the string. This optimizes for size by eliminating the need to
load the pointer each time you print. It also reduces complexity because
you don't need to assign a label to the string.
>
>
>
>
>
> On 9/15/2017 9:44 PM, Glen Hewlett wrote:
>>
>> Hi Again,
>>
>> I just posted Part 2 of my series of blogs about optimizing 6809
assembly language programs.
>>
>>
https://nowhereman999.wordpress.com/2017/09/15/optimizing-6809-assembly-code-part-2-speedup-storing-data-unrolling-loops/
<
https://nowhereman999.wordpress.com/2017/09/15/optimizing-6809-assembly-code-part-2-speedup-storing-data-unrolling-loops/
>
>>
>> Cheers,
>> Glen
>>
>
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco