On 07/16/2018 09:55 AM, Coly Li wrote: > > diff --git a/lib/crc64.c b/lib/crc64.c > new file mode 100644 > index 000000000000..03f078303bd3 > --- /dev/null > +++ b/lib/crc64.c > @@ -0,0 +1,71 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Normal 64bit 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_le[256] is the lookup table of a table-driver 64bit 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@xxxxxxx> > + * > + */ > + > +#include <linux/module.h> > +#include <uapi/linux/types.h> > +#include "crc64table.h" > + > +MODULE_DESCRIPTION("CRC64 calculations"); > +MODULE_LICENSE("GPL"); > + > +__le64 crc64_le_update(__le64 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) ^ (__le64)(*p++)) & 0xFF; > + crc = crc64table_le[t] ^ (crc << 8); > + } > + > + return crc; > +} > +EXPORT_SYMBOL_GPL(crc64_le_update); > + > +__le64 crc64_le(const void *p, size_t len) > +{ > + __le64 crc = 0x0000000000000000ULL; Hi, What's wrong with just using 0ULL ? thanks. > + > + crc = crc64_le_update(crc, p, len); > + > + return crc; > +} -- ~Randy -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
