diff options
author | Thomas Bertschinger <tahbertschinger@gmail.com> | 2024-01-15 23:41:02 -0700 |
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committer | Kent Overstreet <kent.overstreet@linux.dev> | 2024-01-16 01:47:05 -0500 |
commit | f5baaf48e3e82b1caf9f5cd1207d4d6feba3a2e5 (patch) | |
tree | 59f7b0e4667df7a9d3d5a45725f2aaab3e79b4c5 /c_src/linux/crc64.c | |
parent | fb35dbfdc5a9446fbb856dae5542b23963e28b89 (diff) |
move Rust sources to top level, C sources into c_src
This moves the Rust sources out of rust_src/ and into the top level.
Running the bcachefs executable out of the development tree is now:
$ ./target/release/bcachefs command
or
$ cargo run --profile release -- command
instead of "./bcachefs command".
Building and installing is still:
$ make && make install
Signed-off-by: Thomas Bertschinger <tahbertschinger@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'c_src/linux/crc64.c')
-rw-r--r-- | c_src/linux/crc64.c | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/c_src/linux/crc64.c b/c_src/linux/crc64.c new file mode 100644 index 00000000..0ef8ae6a --- /dev/null +++ b/c_src/linux/crc64.c @@ -0,0 +1,56 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Normal 64-bit CRC calculation. + * + * This is a basic crc64 implementation following ECMA-182 specification, + * which can be found from, + * http://www.ecma-international.org/publications/standards/Ecma-182.htm + * + * Dr. Ross N. Williams has a great document to introduce the idea of CRC + * algorithm, here the CRC64 code is also inspired by the table-driven + * algorithm and detail example from this paper. This paper can be found + * from, + * http://www.ross.net/crc/download/crc_v3.txt + * + * crc64table[256] is the lookup table of a table-driven 64-bit CRC + * calculation, which is generated by gen_crc64table.c in kernel build + * time. The polynomial of crc64 arithmetic is from ECMA-182 specification + * as well, which is defined as, + * + * x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x^52 + x^47 + x^46 + x^45 + + * x^40 + x^39 + x^38 + x^37 + x^35 + x^33 + x^32 + x^31 + x^29 + x^27 + + * x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 + + * x^7 + x^4 + x + 1 + * + * Copyright 2018 SUSE Linux. + * Author: Coly Li <colyli@suse.de> + */ + +#include <linux/module.h> +#include <linux/types.h> +#include "crc64table.h" + +MODULE_DESCRIPTION("CRC64 calculations"); +MODULE_LICENSE("GPL v2"); + +/** + * crc64_be - Calculate bitwise big-endian ECMA-182 CRC64 + * @crc: seed value for computation. 0 or (u64)~0 for a new CRC calculation, + or the previous crc64 value if computing incrementally. + * @p: pointer to buffer over which CRC64 is run + * @len: length of buffer @p + */ +u64 __pure crc64_be(u64 crc, const void *p, size_t len) +{ + size_t i, t; + + const unsigned char *_p = p; + + for (i = 0; i < len; i++) { + t = ((crc >> 56) ^ (*_p++)) & 0xFF; + crc = crc64table[t] ^ (crc << 8); + } + + return crc; +} +EXPORT_SYMBOL_GPL(crc64_be); |