Re: [sdcc-devel] Front end / static data

[Sandeep D. <sa...@dd...>]

Hi Michael ,

This maynot be very easy to do..SDCCast.c would be
the place to start... it just creates a tree as if there
are several assignments to array elements in your case
it creates six assignments.

tile[0] = 1;
tile[1] = 2;
...
tile[5] = 6;

we might me able to change this ..if this is a constant
array however the compiler will generate the code differently
it will generate

_tile:
	.db 1,2,3,4,5,6

Sandeep
> 
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> Hi all.  I've added a 'c1' mode to sdcc so that it can be used inside a C
> front end like gcc or lcc.  See --c1mode.  Basically its a mode where it
> compiles pre-processed code into assembler.  I'm using it with a hacked
> version of lcc to give cmd lines like 'lcc -mgbz80 -o big.gb b1.c b2.c
> lib.o'
> 
> My question for the day is:
> For static data like:
> 
> char tile[] = {
>         1, 2, 3, 4, 5, 6
> };
> 
> sdcc generates:
>         ld      bc,#tile
>         ld      a,1
>         ld      (bc),a
>         ld      bc,#tile+1
>         ld      a,2
>         ld      (bc),a ...
> 
> which is incredibly inefficent (6 bytes per static byte).  What I'd like
> it to do is:
> 
>         ld      de,#tile
>         ld      hl,#1_start$
>         ld      bc,#1_end$
>         ldir    (basically a memcpy)
>         jp      1_end$
> 1_start$:
>         .db     1,2,3,4,5,6
> 1_end$:
>         ... next gs init.
> 
> Any clues as to where to start?  I believe the relevent code is in
> SDCCast.c, but I've yet to find where it actually emits the
> genPointerSet.  It seems that theres some interesting tree unfolding going
> on.
> 
> - -- Michael
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-- 
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Sandeep Dutta                        Phone:  650-356-5417
Diab-SDS                             Fax:    650-356-5490
323 Vintage Park Drive               Email:  sa...@dd...
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