40b0b3f8fb2d8 (Thomas Gleixner 2019-06-03 07:44:46 +0200 1) // SPDX-License-Identifier: GPL-2.0-only
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 2) /*
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 3) * crc7.c
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 4) */
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 5)
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 6) #include <linux/types.h>
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 7) #include <linux/module.h>
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 8) #include <linux/crc7.h>
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 9)
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 10)
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 11) /*
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 12) * Table for CRC-7 (polynomial x^7 + x^3 + 1).
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 13) * This is a big-endian CRC (msbit is highest power of x),
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 14) * aligned so the msbit of the byte is the x^6 coefficient
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 15) * and the lsbit is not used.
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 16) */
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 17) const u8 crc7_be_syndrome_table[256] = {
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 18) 0x00, 0x12, 0x24, 0x36, 0x48, 0x5a, 0x6c, 0x7e,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 19) 0x90, 0x82, 0xb4, 0xa6, 0xd8, 0xca, 0xfc, 0xee,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 20) 0x32, 0x20, 0x16, 0x04, 0x7a, 0x68, 0x5e, 0x4c,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 21) 0xa2, 0xb0, 0x86, 0x94, 0xea, 0xf8, 0xce, 0xdc,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 22) 0x64, 0x76, 0x40, 0x52, 0x2c, 0x3e, 0x08, 0x1a,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 23) 0xf4, 0xe6, 0xd0, 0xc2, 0xbc, 0xae, 0x98, 0x8a,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 24) 0x56, 0x44, 0x72, 0x60, 0x1e, 0x0c, 0x3a, 0x28,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 25) 0xc6, 0xd4, 0xe2, 0xf0, 0x8e, 0x9c, 0xaa, 0xb8,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 26) 0xc8, 0xda, 0xec, 0xfe, 0x80, 0x92, 0xa4, 0xb6,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 27) 0x58, 0x4a, 0x7c, 0x6e, 0x10, 0x02, 0x34, 0x26,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 28) 0xfa, 0xe8, 0xde, 0xcc, 0xb2, 0xa0, 0x96, 0x84,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 29) 0x6a, 0x78, 0x4e, 0x5c, 0x22, 0x30, 0x06, 0x14,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 30) 0xac, 0xbe, 0x88, 0x9a, 0xe4, 0xf6, 0xc0, 0xd2,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 31) 0x3c, 0x2e, 0x18, 0x0a, 0x74, 0x66, 0x50, 0x42,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 32) 0x9e, 0x8c, 0xba, 0xa8, 0xd6, 0xc4, 0xf2, 0xe0,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 33) 0x0e, 0x1c, 0x2a, 0x38, 0x46, 0x54, 0x62, 0x70,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 34) 0x82, 0x90, 0xa6, 0xb4, 0xca, 0xd8, 0xee, 0xfc,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 35) 0x12, 0x00, 0x36, 0x24, 0x5a, 0x48, 0x7e, 0x6c,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 36) 0xb0, 0xa2, 0x94, 0x86, 0xf8, 0xea, 0xdc, 0xce,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 37) 0x20, 0x32, 0x04, 0x16, 0x68, 0x7a, 0x4c, 0x5e,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 38) 0xe6, 0xf4, 0xc2, 0xd0, 0xae, 0xbc, 0x8a, 0x98,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 39) 0x76, 0x64, 0x52, 0x40, 0x3e, 0x2c, 0x1a, 0x08,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 40) 0xd4, 0xc6, 0xf0, 0xe2, 0x9c, 0x8e, 0xb8, 0xaa,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 41) 0x44, 0x56, 0x60, 0x72, 0x0c, 0x1e, 0x28, 0x3a,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 42) 0x4a, 0x58, 0x6e, 0x7c, 0x02, 0x10, 0x26, 0x34,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 43) 0xda, 0xc8, 0xfe, 0xec, 0x92, 0x80, 0xb6, 0xa4,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 44) 0x78, 0x6a, 0x5c, 0x4e, 0x30, 0x22, 0x14, 0x06,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 45) 0xe8, 0xfa, 0xcc, 0xde, 0xa0, 0xb2, 0x84, 0x96,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 46) 0x2e, 0x3c, 0x0a, 0x18, 0x66, 0x74, 0x42, 0x50,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 47) 0xbe, 0xac, 0x9a, 0x88, 0xf6, 0xe4, 0xd2, 0xc0,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 48) 0x1c, 0x0e, 0x38, 0x2a, 0x54, 0x46, 0x70, 0x62,
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 49) 0x8c, 0x9e, 0xa8, 0xba, 0xc4, 0xd6, 0xe0, 0xf2
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 50) };
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 51) EXPORT_SYMBOL(crc7_be_syndrome_table);
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 52)
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 53) /**
8276d3b4398d1 (Mauro Carvalho Chehab 2021-01-14 09:04:43 +0100 54) * crc7_be - update the CRC7 for the data buffer
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 55) * @crc: previous CRC7 value
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 56) * @buffer: data pointer
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 57) * @len: number of bytes in the buffer
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 58) * Context: any
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 59) *
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 60) * Returns the updated CRC7 value.
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 61) * The CRC7 is left-aligned in the byte (the lsbit is always 0), as that
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 62) * makes the computation easier, and all callers want it in that form.
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 63) *
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 64) */
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 65) u8 crc7_be(u8 crc, const u8 *buffer, size_t len)
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 66) {
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 67) while (len--)
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 68) crc = crc7_be_byte(crc, *buffer++);
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 69) return crc;
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 70) }
1836eea209546 (George Spelvin 2014-05-10 10:32:57 -0400 71) EXPORT_SYMBOL(crc7_be);
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 72)
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 73) MODULE_DESCRIPTION("CRC7 calculations");
ad241528c4919 (Jan Nikitenko 2007-07-17 04:04:03 -0700 74) MODULE_LICENSE("GPL");
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