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memcpy and const tables

 
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sebdey



Joined: 11 Sep 2003
Posts: 17
Location: Switzerland

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memcpy and const tables
PostPosted: Wed Mar 28, 2007 7:51 am     Reply with quote
Hello,
I am developing an application with a graphical LCD, and am running into the problem of displaying bitmaps on my lcd.

I want to store my bitmaps in rom using a #rom statement. But I then cannot retrieve the correct data using memcpy. Here's my code:

Bitmap declaration and storage
Code:

#define  LOGO 0x0F000
...
#rom int8 LOGO = {0xFF, 0xFF, 0xFF, 0xE0, 0xE0, 0xFF, 0xFF, 0xFF,
                         0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}


In main, after lcd initialisation etc...
Code:

   ...
   glcd_drawbitmap(90,30,LOGO,8,16);
   ...


The glcd_drawbitmap routine
Code:

void
glcd_drawbitmap(int x, int y, int32 bitmapAddress, int width, int height)
{
   int bitmapData[1024];
   int *bitmapPointer=bitmapData;
   int i,j,k;

   height=height>>3;
   memcpy(bitmapPointer, bitmapAddress, width*height);

   
   for(i=0;i<height;i++)
   {
      for(j=0;j<width;j++)
      {
         for(k=0;k<8;k++)
         {
            if(bit_test(*bitmapPointer,k))
               glcd_pixel(x+j,y+(i<<3)+k,ON);
            else
               glcd_pixel(x+j,y+(i<<3)+k,OFF);
         }

         bitmapPointer++;
      }
   }
}       


This will only output garbage (and always the same garbage) on my lcd, I suspect the memcpy to not copy the correct area of my flash into the bitmapData table. What am I doing wrong ? I searched the forum for memcpy and #rom, but nothing really helped me...

Thanks
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Wed Mar 28, 2007 11:29 am     Reply with quote
Make a small test program where you test only the memcpy()
function. Study the function documentation. Look at the .LST file
to see what it's doing.

By a small program, I mean less than 6 lines of code in main().
Concentrate on fixing the memcpy() problem only. Don't write
to the LCD. Don't #include the LCD driver files. Use printf()
to a terminal window for output. Keep it very simple.

If you can't solve it, then post your test program. Be sure to post
all the #include, #use and #fuses statements. Also post your compiler
version.
me, sebdey
Guest
PostPosted: Thu Mar 29, 2007 12:43 am     Reply with quote
Thanks PCM,
but here I am not looking for a lesson but an answer from someone who could reduce my development time...

I have already solved my problem by other means, i.e. declaring the arrays as:

Code:

#define LOGO_ID   0
const int8 LOGO[16] = {0xFF, 0xFF, 0xFF, 0xE0, 0xE0, 0xFF, 0xFF, 0xFF,
                               0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};

#define BITMAP1_ID   1
const int8 BITMAP1[length] = {data...};

#define BITMAP2_ID   2
const int8 BITMAP2[length] = {data...};

...


and then reading them in my glcd_drawbitmap by using:

Code:

(...)
switch (bitmapID)
{
   case LOGO_ID:
      memcpy(bitmapPointer,LOGO, width*height);
      break;
   case BITMAP1_ID:
      memcpy(bitmapPointer,BITMAP1, width*height);
      break;
   (...)



But even if this is working, it's not what I want. If no one is willing to give me a short and quick answer, I don't want to lose time trying things that I already tried for hours.
I have done tests with memcpy and standard ram arrays and also with const rom arrays and it works, but no chance with a #rom memory definition... Maybe is this completely impossible and I should resolve it with a read_program_memory or my current solution...

Have a good day...
kevcon



Joined: 21 Feb 2007
Posts: 142
Location: Michigan, USA

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PostPosted: Thu Mar 29, 2007 7:40 am     Reply with quote
Because CCS dosen't handle ROM pointers correctly ( yet? ), You have to fake it out and write your own routines.

This is geard towards PIC18s, it may work for you, but I don't know for sure because I don't know what chip you are using.


Code:

#define TBLPTRU 0xFF8
#define TBLPTRL 0xFF6
#define TABLAT   0xFF5

#byte   _TBLPTRU = TBLPTRU
#byte   _TBLPTRL = TBLPTRL
#byte   _TABLAT = TABLAT

void rom_to_ram_memcpy(int8 *ramptr, int8 *romptr, int16 numberofBytes);





Code:


#define  LOGO 0x01000
#rom int8 LOGO = { 0x12, 0x34 }
int8 bitMapData[ 16 ];

void main( void )
{



   int8 *bitMapPointer = bitMapData;

   rom_to_ram_memcpy( bitMapPointer, LOGO, 2 );



}


void rom_to_ram_memcpy(int8 *ramptr, int8 *romptr, int16 numberofBytes)
{

   char *_TBLPTR;
#locate _TBLPTR = TBLPTRL

//Setup ROM TABLE Pointer
   _TBLPTRU = 0x00;
   _TBLPTR = romptr;


   for (; numberofBytes-- ; ramptr++ ) {
#asm
      TBLRD   *+
#endasm

      *ramptr = _TABLAT;
   }
   

}
_sebdey
Guest
PostPosted: Thu Mar 29, 2007 8:53 am     Reply with quote
Thanks for your answer kevcon !

I will then have to see which method is the best for my project in terms of ease of use/implementation/scalability....

Btw, my fault, I forgot to mention that I am using 18F4620, and 3.235...

Have a good day/night/evening !
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