2D arrays?

lassethomsen

Hi.

Im in a need for a 2D array, but i cant find anyway to create one.
Does the SPIN language not support arrays larger than one dimension?

rjo_

You can do anything with Spin...

Let's say that you have a 2 dimensional array of data NM, where N is the number of columns and M is the number of rows which you wanted to store in a 1 dimensional array... and you have the base address of your 1 dimensional array.... data that you want to put into i,j would place at

address (i,j)=base address+ i + j*N.

rjo_

and a 3 dimensional array could be created

address (i,j,k)= base address + i + j*N + k*N*M

Kaio

For a 2D array you can also use code like this. This avoids the multiplication if you would be use only one array as rjo_ has mentioned.

VAR
  LONG myArray[noparse][[/noparse] 2]   '2D array with 2 rows and 10 columns
  BYTE myArray0[noparse][[/noparse]10]  'first row with 10 columns
  BYTE myArray1[noparse][[/noparse]10]  'second row with 10 columns


PUB initArray | i, j
  
  'initialize memory pointer for rows
  LONG[noparse][[/noparse]@myArray][noparse][[/noparse] 0] := @myArray0
  LONG[noparse][[/noparse]@myArray][noparse][[/noparse] 1] := @myArray1

  'example how to access the 2D array
  repeat i from 0 to 1
    repeat j from 0 to 9
      BYTE[noparse][[/noparse]LONG[noparse][[/noparse]@myArray][noparse][[/noparse] i]][noparse][[/noparse] j] := 0 

The LONG array is used to store the memory pointer of the arrays used for the rows. For performance reason it is recommendable to use the lesser size of dimension for the rows.
The BYTE arrays stores the data, this could be also WORD or LONG.

It is possible to use this for more dimensions, but I think it could be to complicated and not readable.