floating point on nds...

[21o6]

hi again :D

i wanted to display a sinewave on screen but ran into several
problems, which made me do a simple floatingpoint-testprogram:

Program blah;
{$APPTYPE ARM9}
{$DEFINE ARM9}
{$MODE OBJFPC}

uses
  cTypes;

{$INCLUDE NDS.INC}

Var
  NewX,NewY : Integer;
  a,s,d : integer;
  i : real;

  Dummy : String;

Begin
  consoleDemoInit();
  videoSetMode(MODE_FB0);
  vramSetBankA(VRAM_A_LCD);

  lcdSwap;

  i := 0;
  newy := 0;

  for a := 0 to 255 do
  Begin
    newy := trunc(i);
    i:=i+1;

    vram_A[(95 + NewY) * 256 + a] := rgb15(31,31,31);

    Str(i,Dummy);
    Dummy := Dummy + ' ';

    printf(@Dummy+1);
  End;

  While True do;
end.

This produces:



... but when i replace "real" with "integer" it works normally, shown here:




shouldn't both ways produce the same result, as i only increment
a variable by 1?

oh and: is there any other way simple way to output a non-PChar? :D

[dmantione]

This indeed smells like a bug. Francesco, does NDS use fpu opcodes or
softfpu calls?

Despite the bug, the Nintendo devices are probably a bit too slow for
floating point calculations; use an old fashioned sine table.

[JSoftware]

Weren't there a fixedpoint unit posted here a while ago?

[21o6]

i wanted to create a sinetable, but that gave me odd results ... so i made
this testprogram.

err... i guess i found the problem. as far as i understand, the nds does not
support floating point ... it uses fixed point arithmetics.
see: http://dev-scene.com/NDS/Tutorials_Day_2

shame on me for not informing myself enough about the hardware.

thanks anyway :D

[Legolas]

As far as I remember, Florian activated softfpu on arm compiler some months ago.

[21o6]

but... it SHOULD work with i:=i+1, shouldn't it??

i'm confused.

[Legolas]

I have tested your code and it works as expected here (on no$gba and ideas emulator) with fpc trunk 2.3. Maybe it is a bug related to 2.1.4... :think:

[21o6]

i guess you've used arm-linux, right?

actually, i think i misunderstand something.

as far as i can see, there is no need to install fpc, as long as ppcarmnds (=fpc4nds),
devkitpro and libnds are installed...

how i know? i have downloaded 213 for i386 (which of course, like 214) does
not natively support ARM (at least i can't select a target for it) ...
but i thought "ok, just do it" and copied libnds and fpc4nds into the
directory... and as expected: no change at all.

what am i doing wrong? i mean, why should i bother installing fpc if it's not
needed at all?? i can't see where ppcarmnds connects to fpc...

[21o6]

i wanted to tell you that i've rebuild fpc4nds from ground up and
that there are no more errors with the code i've posted :D

[Legolas]

i wanted to tell you that i've rebuild fpc4nds from ground up and
that there are no more errors with the code i've posted

Cool
However, fpc4nds 2.1.4 worked fine too, so I really don't know what appened :?