URL:
<https://savannah.nongnu.org/patch/?10101>
Summary: util/crc16.h: improved _crc_xmodem_update (smaller &
faster)
Project: AVR C Runtime Library
Submitted by: sten
Submitted on: Sun 29 Aug 2021 09:20:55 PM UTC
Category: None
Priority: 5 - Normal
Status: None
Privacy: Public
Assigned to: None
Originator Email:
Open/Closed: Open
Discussion Lock: Any
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Details:
The attached patch improves the _crc_xmodem_update algorithm. The improved
algorithm uses 14 instructions instead of the original 25. Additionally the
temporary variables have less strict constraints (=r instead of =d), and r0 is
not clobbered.
I have successfully tested the new algorithm with all possible inputs (65536 *
256) against the original algorithm. The test was run in simulavr. See
attached files main.c, orig_crc.c and run_test.sh
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File Attachments:
-------------------------------------------------------
Date: Sun 29 Aug 2021 09:20:55 PM UTC Name: patch_crc_xmodem_update.txt
Size: 2KiB By: sten
<http://savannah.nongnu.org/patch/download.php?file_id=51830>
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Date: Sun 29 Aug 2021 09:20:55 PM UTC Name: main.c Size: 1KiB By: sten
<http://savannah.nongnu.org/patch/download.php?file_id=51831>
-------------------------------------------------------
Date: Sun 29 Aug 2021 09:20:55 PM UTC Name: orig_crc.c Size: 116B By: sten
<http://savannah.nongnu.org/patch/download.php?file_id=51832>
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Date: Sun 29 Aug 2021 09:20:55 PM UTC Name: run_test.sh Size: 51B By: sten
<http://savannah.nongnu.org/patch/download.php?file_id=51833>
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