This is merely a historical archive of years 2008-2021, before the migration to mailman3.
A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/tetra@lists.osmocom.org/.
Christian Vogel vogelchr at vogel.cxHi, after a remark by Harald about bitwise CRC calculation and seeing the crc_simple code in lower_mac, I've thought about how to implement "optimized" routines using a table-based approach operating on our pbit_t/ubit_t arrays in libosmocore/master. People on IRC consider it more tetra-specific though, so I'm posting this here for advice on where to put it. The usage is to first create the table via osmo_crc16_table_init(*table,polynomial) and then to encode bits using osmo_crc16() - default, operates on pbit_t[] osmo_crc16_ubits() - operate on ubit_t[] osmo_crc16_ubit() - one single bit, takes polynomial as first arg! osmo_crc16_pbit() - operate on 1-7 bits in a pbit_t It passes the crc_test ported to the new routines. $ ./crc_test # osmo-tetra The CRC is now: 4129/0x1021 The CRC is now: 4129/0x1021 The CRC is now: 61905/0xf1d1 The CRC is now: 65534/0xfffe The CRC is now: 57073/0xdef1 The CRC is now: 7439/0x1d0f Decoded successfully. $ tests/crc/crc_test # this patch, in libosmocore First elements of table for CRC with poly 0x1021: 0000 1021 2042 3063 4084 50a5 60c6 70e7 8108 9129 a14a b16b c18c d1ad e1ce f1ef The CRC is now: 4129/0x1021 The CRC is now: 4129/0x1021 The CRC is now: 61905/0xf1d1 The CRC is now: 65534/0xfffe packed bits: 10 b0 be 00 83 07 d3 3d ef 10 The CRC is now: 57073/0xdef1 ...packed: 57073/0xdef1 packed bits: 10 b0 be 00 83 07 d3 3d ef 10 The CRC is now: 7439/0x1d0f Decoded successfully. Chris -------------- next part -------------- A non-text attachment was scrubbed... Name: 0001-Table-based-msb-first-crc16-functions.patch Type: application/octet-stream Size: 5381 bytes Desc: not available URL: <http://lists.osmocom.org/pipermail/tetra/attachments/20110123/a41987cc/attachment.obj> -------------- next part -------------- A non-text attachment was scrubbed... Name: 0002-Test-for-osmo_crc16-routines-based-on-Harald-s-crc_t.patch Type: application/octet-stream Size: 4473 bytes Desc: not available URL: <http://lists.osmocom.org/pipermail/tetra/attachments/20110123/a41987cc/attachment-0001.obj>