diff options
| author | jcorgan <jcorgan@221aa14e-8319-0410-a670-987f0aec2ac5> | 2007-02-06 00:10:32 +0000 |
|---|---|---|
| committer | jcorgan <jcorgan@221aa14e-8319-0410-a670-987f0aec2ac5> | 2007-02-06 00:10:32 +0000 |
| commit | c4e072e8a58800f2dfd6c1e5e95009dd783061be (patch) | |
| tree | 575da3b788adacda6aeff19c730394ce1ddbdbc3 /gnuradio-core/src/python/gnuradio/packet_utils.py | |
| parent | b431e9f594607e61866aef2bab73240c21c4cc6f (diff) | |
Merged r4354:4390 from developer branch jcorgan/digital into trunk.
git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@4391 221aa14e-8319-0410-a670-987f0aec2ac5
Diffstat (limited to 'gnuradio-core/src/python/gnuradio/packet_utils.py')
| -rw-r--r-- | gnuradio-core/src/python/gnuradio/packet_utils.py | 31 |
1 files changed, 20 insertions, 11 deletions
diff --git a/gnuradio-core/src/python/gnuradio/packet_utils.py b/gnuradio-core/src/python/gnuradio/packet_utils.py index 59b1353662..182c80cdc8 100644 --- a/gnuradio-core/src/python/gnuradio/packet_utils.py +++ b/gnuradio-core/src/python/gnuradio/packet_utils.py @@ -86,22 +86,26 @@ def string_to_hex_list(s): return map(lambda x: hex(ord(x)), s) -def whiten(s): +def whiten(s, o): sa = Numeric.fromstring(s, Numeric.UnsignedInt8) - z = sa ^ random_mask_vec8[0:len(sa)] + z = sa ^ random_mask_vec8[o:len(sa)+o] return z.tostring() -def dewhiten(s): - return whiten(s) # self inverse +def dewhiten(s, o): + return whiten(s, o) # self inverse -def make_header(payload_len): - return struct.pack('!HH', payload_len, payload_len) +def make_header(payload_len, whitener_offset=0): + # Upper nibble is offset, lower 12 bits is len + val = ((whitener_offset & 0xf) << 12) | (payload_len & 0x0fff) + #print "offset =", whitener_offset, " len =", payload_len, " val=", val + return struct.pack('!HH', val, val) def make_packet(payload, samples_per_symbol, bits_per_symbol, - access_code=default_access_code, pad_for_usrp=True): + access_code=default_access_code, pad_for_usrp=True, + whitener_offset=0): """ - Build a packet, given access code and payload. + Build a packet, given access code, payload, and whitener offset @param payload: packet payload, len [0, 4096] @param samples_per_symbol: samples per symbol (needed for padding calculation) @@ -109,6 +113,7 @@ def make_packet(payload, samples_per_symbol, bits_per_symbol, @param bits_per_symbol: (needed for padding calculation) @type bits_per_symbol: int @param access_code: string of ascii 0's and 1's + @param whitener_offset offset into whitener string to use [0-16) Packet will have access code at the beginning, followed by length, payload and finally CRC-32. @@ -116,6 +121,9 @@ def make_packet(payload, samples_per_symbol, bits_per_symbol, if not is_1_0_string(access_code): raise ValueError, "access_code must be a string containing only 0's and 1's (%r)" % (access_code,) + if not whitener_offset >=0 and whitener_offset < 16: + raise ValueError, "whitener_offset must be between 0 and 15, inclusive (%i)" % (whitener_offset,) + (packed_access_code, padded) = conv_1_0_string_to_packed_binary_string(access_code) (packed_preamble, ignore) = conv_1_0_string_to_packed_binary_string(preamble) @@ -127,7 +135,8 @@ def make_packet(payload, samples_per_symbol, bits_per_symbol, if L > MAXLEN: raise ValueError, "len(payload) must be in [0, %d]" % (MAXLEN,) - pkt = ''.join((packed_preamble, packed_access_code, make_header(L), whiten(payload_with_crc), '\x55')) + pkt = ''.join((packed_preamble, packed_access_code, make_header(L, whitener_offset), + whiten(payload_with_crc, whitener_offset), '\x55')) if pad_for_usrp: pkt = pkt + (_npadding_bytes(len(pkt), samples_per_symbol, bits_per_symbol) * '\x55') @@ -156,13 +165,13 @@ def _npadding_bytes(pkt_byte_len, samples_per_symbol, bits_per_symbol): return byte_modulus - r -def unmake_packet(whitened_payload_with_crc): +def unmake_packet(whitened_payload_with_crc, whitener_offset=0): """ Return (ok, payload) @param whitened_payload_with_crc: string """ - payload_with_crc = dewhiten(whitened_payload_with_crc) + payload_with_crc = dewhiten(whitened_payload_with_crc, whitener_offset) ok, payload = gru.check_crc32(payload_with_crc) if 0: |