How move a byte one byte to left in this array

The Puma · Joined: 23 Apr 2004 Posts: 227 Location: The Netherlands

How can i move the five bytes at position 45 one byte each other to left
The five bytes make the letter A

It is used for making a routeting message on the dot matrix displays

I need a efficient routine to do this

Ttelmah · Guest

You can't.
Since this is a constant array, you cannot move the data at all.
However may I suggest a possible 'route'. If you have the address you want to 'start' reading from the array as 'address', and the _offset_ (how much you want to move the data), in a signed variable called 'offset', then:

message[(address+offset)%50]

will access the array as if it started 'offset' bytes from where it really does. You can increment, and decrement 'offset', to move where you access the array from.

Best Wishes

andreluizeng · Joined: 04 Apr 2006 Posts: 117 Location: Brasil

you can do this if you use a pointer to that array.
for example:

Ttelmah · Guest

You can't use pointers to constant arrays in CCS. Hence my suggestion to use an offset byte instead.

Best Wishes

andreluizeng · Joined: 04 Apr 2006 Posts: 117 Location: Brasil

i thought that it was possible...
if is not..
sorry.

so.. he can make it using a dinamic array...

char *message;

message = (char *) malloc (sizeof (char) * 50);

regards.
_________________
Andre

Ttelmah · Guest

He doesn't even need to fiddle around like this. If the word 'const' is just removed from the declaration, the array will be a simple variable one, and the compiler will handle the initialisation as well. However the 'downside' of the variable array, is the need for 50 bytes of RAM (which may be a problem on some PICs). On smaller PICs, using the offset to the const array may be the better solution.

Best Wishes

The Puma · Joined: 23 Apr 2004 Posts: 227 Location: The Netherlands

Is there another option to do this on a simple matter

I need this to shift data on 10 dot matrix displays by one column each
Maybe another structure

Ducky · Guest

remove the const from your array declaration....than you can use the rotate_right or rotate_left function.

for example...

char message[50] = {
0x00, 0x00, 0x00, 0x00, 0x00, // 0
0x00, 0x00, 0x00, 0x00, 0x00, // 5
0x00, 0x00, 0x00, 0x00, 0x00, // 10
0x00, 0x00, 0x00, 0x00, 0x00, // 15
0x00, 0x00, 0x00, 0x00, 0x00, // 20
0x00, 0x00, 0x00, 0x00, 0x00, // 25
0x00, 0x00, 0x00, 0x00, 0x00, // 30
0x00, 0x00, 0x00, 0x00, 0x00, // 35
0x00, 0x00, 0x00, 0x00, 0x00, // 40
0x7E, 0x7E, 0x11, 0x11, 0x7E // 45
};
rotate_left(message,50);

Ducky · Guest

rotate_x rotates only one bit

the following rotates one byte....sorry

int loop = 0;
for(loop = 0; loop < 8;loop++)
rotate_right(message,50);