[Discuss-gnuradio] Tag propagaton bug in pack_k_bits_bb

[Eugene Grayver]

Hello,

I found a tag propagation bug in pack_k_bits_bb.  Example python file to demonstrate the bug is below.  This block takes every 2 bits and packs them into one output.  Thus, a tag on input 0 should come out on output 0, and tag on input 7 should come out on output 3.  However, as can be seen from this example, the second tag comes out on output 4.  This is probably due to the way sync_decimator does tag propagation: round(input_index / decimation).  However, that is NOT the correct approach for this block.

Eugene

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from gnuradio import gr, blocks

import pmt

top = gr.top_block()

tag1 = gr.python_to_tag((0, pmt.intern('A'), pmt.PMT_NIL))

tag2 = gr.python_to_tag((7, pmt.intern('B'), pmt.PMT_NIL))

src = "" tags=[tag1, tag2])

packer = blocks.pack_k_bits_bb(2)

dbg = blocks.tag_debug(gr.sizeof_char,'A')

top.connect(src, packer, dbg)

top.run()

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Eugene Grayver, Ph.D.
Aerospace Corp., Sr. Eng. Spec.
Tel: 310.336.1274
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