Error when calculating modulo 2+512=2 for CUDA

Accelerated Computing CUDA CUDA Programming and Performance
1

Hi All,

I’m currently working on a CFD simulation program. I have problems when calculating a difference. The boundaries are periodic, so I choose to use the modulo, and to make it faster, the resolution has to be 2^n.

The problem is the following (col=0;row=1m;KsiMax=512, inside kernel functions)

[codebox] (col+2)&(KsiMax-1)+row*KsiMax //->result 2 according to CUDA [/codebox]

[codebox] int Value=row*KsiMax;

           Value+=(col+2)&(KsiMax-1);                 // ->result 514 according to CUDA[/codebox]

I have really no idea, why is 2+512 for the CUDA 2???

Yours sincerely:

                                                     Laszlo Daroczy
2

Because in C, + has precedence over & so you need to put parenthesis?

3

Thanks, I will try.