2D Matrix Rotation

**Art** · - 15th February 2010, 03:07

Hi Guys,
Does anyone have a 2D matrix rotation algo they'd like to share?
I'd like to rotate all bits in a byte array so:

byte0: 00001110
byte1: 00001111
byte2: 00001111
byte3: 11111111
byte4: 11111111
byte5: 00001111
byte6: 00001111
byte7: 00001110

becomes:

byte0: 01111110
byte1: 11111111
byte2: 11111111
byte3: 11111111
byte4: 00011000
byte5: 00011000
byte6: 00011000
byte7: 00011000

I can do this if I have a list of coordinates like this:
x_new = y_old
y_new = 1 - (x_old - (8 - 2))
Do this for every coordinate (64 times) and the result is what I want.
Art.

**Kamikaze47** · - 15th February 2010, 06:53

off the top of my head this is what i came up with (untested):

Code:

array          var byte[8]
array_rotated  var byte[8]
bit_num        var byte
byte_num       var byte
temp           var byte
result         var byte

for byte_num=0 to 7
    for bit_num=0 to 7
        temp=array[7-bit_num]
        temp=temp>>byte_num
        result=result<<1
        result.0=temp.0
    next bit_num
    array_rotated[byte_num]=result
next byte_num

*edit* fixed some mistakes
*edit* fixed one last mistake

**Art** · - 15th February 2010, 11:35

I did come up with a way using a very verbose drawn out method that referenced every bit,
and copies one array to the other, but this looks much neater

I'll give it a try, thanks!

**Kamikaze47** · - 15th February 2010, 17:12

If it works, you can repay me by sending me some of those DSE component racks you were bragging about on OCAU. Hehe j/k.

**Art** · - 15th February 2010, 22:16

It's a small world

There was a little more to it than bragging.
I was trying to find interested people to get together to possibly buy the next lot in a few months.
But I also try to show off a bit

Cheers, Art.