On standard dataflow graphs, there is always 2 phases to get a continuous dataflow without restarting the BDs.
This means that the number of BDs, as computed hereafter, is multiplied by 2.
Zero padding is a special case. Let’s look at these 2 cases:
In the first case a single BD is enough, it will generate the zeros before and after the tile on the fly using the 2 registers D0_Zero_Before and D0_Zero_After set to 4.
In case 2 3 BDs will be necessary:
The first one with D0_Zero_Before set to 4.
The second one with these 2 registers set to 0.
The third one with D0_Zero_After set to 4.