I'm creating a Python block that calculates a custom FFT. I need to ensure that I get at least 1024 data points for every input to the block.
From my reading, it looks like I should just be able to do this with the forecast() function in the Python block. So I've done this:
class blk(gr.sync_block): # other base classes are basic_block, decim_block, interp_block
def __init__(self, bandWidthMHz=100.0): # only default arguments here
"""arguments to this function show up as parameters in GRC"""
gr.sync_block.__init__(
self,
name='test', # will show up in GRC
in_sig=[np.complex64],
out_sig=[np.float32]
)
# if an attribute with the same name as a parameter is found,
# a callback is registered (properties work, too).
self.bandWidthMHz = bandWidthMHz
self.MM = 0
def forecast(self, noutput_items, ninput_items_required=1024):
ninput_items_required[0] = 1024
def work(self, input_items, output_items):
if (np.shape(input_items[0])[0] < 1024):
print(np.shape(input_items[0]))
output_items[0] = [3.5, -1, 0, 1]
return len(output_items[0])
According to the docs, if I set ninput_items_required[0] = 1024, then forecast should prevent the work from being done until I have at least 1024 input values.
Nevertheless, the print statement I have in the work function is showing that the program gets to the work even when the input_items[0] is much less (e.g. 24, 102, 960) than 1024.
Can anyone point me in the right direction? Can I just have the work function skip execution if len(input_items[0]) < 1024? Or, will that drop data?
Thanks for your help.
-Tony
p.s. I'm just doing this in a Python block from the GRC. So this is not a custom OOT module. Does that matter?