[C related] Structs, records, pointers...

[Legolas]

I'm a bit in stuck... I need to convert following code to pascal:

#define OAM_SUB       ((uint16*)0x07000400)

SpriteEntry OAMCopySub[128]; 
void updateOAM(void) {
	unsigned int i;
	for&#40;i = 0; i < 128 * sizeof&#40;SpriteEntry&#41; / 4 ; i++&#41;
	&#123;
		&#40;&#40;uint32*&#41;OAM_SUB&#41;&#91;i&#93; = &#40;&#40;uint32*&#41;OAMCopySub&#41;&#91;i&#93;;
	&#125;
&#125;

where SpriteEntry is a struct. OAM_SUB is translated as
[pascal]const
OAM_SUB : puint16 = pointer($07000400);[/pascal]

The problem is that I can't figure a way to typecast hte array of record to OAM_SUB :scratch:

[VilleK]

You can do something like this:

type
  PInt32 = ^integer;
var
  Data : array[0..10] of TMyRecord;
begin
  PInt32(@Data)^ := 42;
end;

[JernejL]

I'm a bit in stuck... I need to convert following code to pascal:

#define OAM_SUB       ((uint16*)0x07000400)

SpriteEntry OAMCopySub[128]; 
void updateOAM(void) {
	unsigned int i;
	for&#40;i = 0; i < 128 * sizeof&#40;SpriteEntry&#41; / 4 ; i++&#41;
	&#123;
		&#40;&#40;uint32*&#41;OAM_SUB&#41;&#91;i&#93; = &#40;&#40;uint32*&#41;OAMCopySub&#41;&#91;i&#93;;
	&#125;
&#125;

where SpriteEntry is a struct. OAM_SUB is translated as
[pascal]const
OAM_SUB : puint16 = pointer($07000400);[/pascal]

The problem is that I can't figure a way to typecast hte array of record to OAM_SUB :scratch:

declare stuff like this:

OAMCopySub = packed record or something

POAMCopySub = ^OAMCopySub; // a pointer variant

then use POAMCopySub in variable and set it to that pointer.

[Legolas]

Thanks to all!
Now I'm @ work, so I'll try later

[Legolas]

Ok, I have found a solution that works, or at least that compiles :roll:
I have tried this "monster":
[pascal] for i := 0 to (128 * sizeof(SpriteEntry) div 4) - 1 do
pu32((@OAM_SUB[i])^) := pu32((@OAMCopySub[i])^);[/pascal]

As I have said before, it compiles, though it does not work as expected, because I get corrupted sprites. Hopefully it should be a wrong (or missing) typecast somewhere...
[size=9px]Bug hunting time[/size] :rambo:

[JernejL]

pointer wrestling in C is bad enough, translating such code is one of worst tasks you can get, good luck :/

[Setharian]

I'm not familiar with GBA (?) types, so I'll use the regular Delphi ones....

var
  OAMCopySub: array[0..127] of SpriteEntry;

...

procedure UpdateOAM;
type
  PLongs ^TLongs;
  TLongs = array[0..MAXWORD-1] of Longword;
begin
  for i := 0 to (128 * SizeOf(SpriteEntry) div SizeOf(Longword)) -1 do
  begin
    PLongs(OAM_SUB)^[i] := PLongs(@OAMCopySub)^[i];  
  end;
end;

if pu32 is ^Longword, then u32 should be a Longword and thus all you have to do is replace Longword by u32

on the other hand if you have a "Move" procedure at your disposal you could as well use it.....

Move(OAMCopySub, OAM_SUB^, SizeOf(OAMCopySub));

I think this is the easiest solution if it can be done...

[Legolas]

Yes, in fact it is NDS code :mrgreen:

Move could be a solution, but it works only on Dualis emulator; on real hardware the memory is not copied at all. To tell short, I have decided to replace this loop by a dma copy, that takes care to copy the right amount of bytes at time.
[pascal]dmaCopy(@OAMCopySub, OAM_SUB, sizeof(OAMCopySub));[/pascal]

[Legolas]

I'm resuming this old thread because I need some other help
Well, I have converted a struct to pascal but I have some alignment problems. The original code is this:

typedef struct sTransferRegion {
  uint32 heartbeat;         
	int16 touchX,   touchY;   
	int16 touchXpx, touchYpx; 
	int16 touchZ1,  touchZ2;  
	uint16 tdiode1,  tdiode2; 
	uint32 temperature;       
	uint16 buttons;           
	union {
		uint8 curtime[8];       
    struct {
			u8 rtc_command;
			u8 rtc_year;          
			u8 rtc_month;         
			u8 rtc_day;           

			u8 rtc_incr;
			u8 rtc_hours;         
			u8 rtc_minutes;       
			u8 rtc_seconds;       
    };
  };
	uint16 battery;           
	uint16 aux;               
	pTransferSound soundData;
  vuint32 mailAddr;
  vuint32 mailData;
  vuint8 mailRead;
  vuint8 mailBusy;
  vuint32 mailSize;
} TransferRegion, * pTransferRegion;

And this is my (bad) translation
[pascal] sTransferRegion = record
heartbeat: cuint32;
touchX, touchY: cint16;
touchXpx, touchYpx: cint16;
touchZ1, touchZ2: cint16;
tdiode1, tdiode2: cuint16;
temperature: cuint32;
buttons: cuint16;
union: record
case integer of
0: (curtime: array [0..7] of cuint;
1: (
rtc_command: cuint8;
rtc_year: cuint8;
rtc_month: cuint8;
rtc_day: cuint8;
rtc_incr: cuint8;
rtc_hours: cuint8;
rtc_minutes: cuint8;
rtc_seconds: cuint8;
);
end;
battery: cuint16;
aux: cuint16;
soundData: pTransferSound;
mailAddr: cuint32;
mailData: cuint32;
mailRead: cuint8;
mailBusy: cuint8;
mailSize: cuint32;
end;
TransferRegion = sTransferRegion;
pTransferRegion = ^sTransferRegion;
[/pascal]


I think that the problem is in the union part... the nested record I have used is an ugly trick to avoid the limitation that forces to put variant parts as the last field in a record.
Any better solution? :scratch:

[JSoftware]

my first idea was that it should be a packed record but having a second look it seems to align just fine...

edit: or wait a minute. won't the last field be scewed into the last 4 padded bytes?