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lib: crc: add CRC-32K/4.2

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This adds the best HD=4 CRC32 polynomial. The discovery
is the result of research by Philip Koopman of Carnegie
Mellon University, and is well documented at
https://users.ece.cmu.edu/~koopman/crc/.

The user is given the option of trading 1024B of RAM to
improve the execution speed. The unit tests are parameterized
with this KConfig option.

Signed-off-by: JP Hutchins <jp@intercreate.io>
This commit is contained in:
JP Hutchins 2025-03-22 18:55:14 -07:00 committed by Benjamin Cabé
parent db6b126e90
commit fe6366b804
7 changed files with 152 additions and 1 deletions
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32
include/zephyr/sys/crc.h
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@ -5,6 +5,7 @@
* Copyright (c) 2015 Runtime Inc
* Copyright (c) 2018 Google LLC.
* Copyright (c) 2022 Meta
* Copyright (c) 2024 Intercreate, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
@ -69,6 +70,7 @@ enum crc_type {
CRC24_PGP, /**< Use @ref crc24_pgp */
CRC32_C, /**< Use @ref crc32_c */
CRC32_IEEE, /**< Use @ref crc32_ieee */
CRC32_K_4_2, /**< Use @ref crc32_k_4_2_update */
};
/**
@ -263,6 +265,32 @@ uint32_t crc32_ieee_update(uint32_t crc, const uint8_t *data, size_t len);
uint32_t crc32_c(uint32_t crc, const uint8_t *data,
size_t len, bool first_pkt, bool last_pkt);
/**
* @brief Update a CRC-32K/4.2 (*op) (Koopman) checksum. This is a good HD=4
* checksum up to 2,147,483,615 bits and HD=5/6 up to 6,167 bits.
*
* Hamming Distance and properties:
*
* - Polynomial: 0x93a409eb
* - reflect-in: false
* - initial value (xor-in): provided by caller as crc argument (0xFFFFFFFF is OK)
* - reflect-out: false
* - xor-out: 0
* - HD=4 @ 2,147,483,615 bits
* - HD=5 @ 6,167 bits
* - HD=6 @ 6,167 bits
* - HD=7 @ 148 bits
*
* Reference: https://users.ece.cmu.edu/~koopman/crc/crc32.html
*
* @param crc CRC32 checksum that needs to be updated.
* @param data Pointer to data on which the CRC should be calculated.
* @param len Data length.
*
* @return CRC32 value.
*/
uint32_t crc32_k_4_2_update(uint32_t crc, const uint8_t *data, size_t len);
/**
* @brief Compute CCITT variant of CRC 8
*
@ -378,7 +406,7 @@ uint32_t crc24_pgp_update(uint32_t crc, const uint8_t *data, size_t len);
* @param type CRC algorithm to use.
* @param src Input bytes for the computation
* @param len Length of the input in bytes
* @param seed Value to seed the CRC with
* @param seed Seed or existing CRC value to update
* @param poly The polynomial to use omitting the leading coefficient
* @param reflect Should we use reflected/reversed values or not
* @param first Whether this is the first packet in the stream.
@ -425,6 +453,8 @@ static inline uint32_t crc_by_type(enum crc_type type, const uint8_t *src, size_
return crc32_c(seed, src, len, first, last);
case CRC32_IEEE:
return crc32_ieee_update(seed, src, len);
case CRC32_K_4_2:
return crc32_k_4_2_update(seed, src, len);
default:
break;
}

1
lib/crc/CMakeLists.txt
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@ -1,6 +1,7 @@
# SPDX-License-Identifier: Apache-2.0
zephyr_sources_ifdef(CONFIG_CRC
crc32k_4_2_sw.c
crc32c_sw.c
crc32_sw.c
crc24_sw.c

7
lib/crc/Kconfig
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@ -1,4 +1,5 @@
# Copyright (c) 2016,2023 Intel Corporation
# Copyright (c) 2024 Intercreate, Inc.
# SPDX-License-Identifier: Apache-2.0
#
config CRC
@ -13,4 +14,10 @@ config CRC_SHELL
select POSIX_C_LIB_EXT
help
Enable CRC checking for memory regions from the shell.
config CRC32_K_4_2_TABLE_256
bool "Use 256-length table for CRC32-K/4.2"
help
Enable the 256-length instead of 16-length table for CRC32-K/4.2.
endif # CRC

84
lib/crc/crc32k_4_2_sw.c Normal file
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@ -0,0 +1,84 @@
/*
* Copyright (c) 2024 Intercreate, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <zephyr/sys/crc.h>
uint32_t crc32_k_4_2_update(uint32_t crc, const uint8_t *const data, const size_t len)
{
#if defined(CONFIG_CRC32_K_4_2_TABLE_256)
/**
* CRC table generated from polynomial 0x93a409eb CRC-32K/4.2 (*op) (Koopman)
*
* pycrc --width 32 --poly 0x93a409eb --reflect-in False --xor-in 0 --reflect-out False
* --xor-out 0 --generate table --table-idx-width 8
*/
static const uint32_t table[256] = {
0x00000000, 0x93a409eb, 0xb4ec1a3d, 0x274813d6, 0xfa7c3d91, 0x69d8347a, 0x4e9027ac,
0xdd342e47, 0x675c72c9, 0xf4f87b22, 0xd3b068f4, 0x4014611f, 0x9d204f58, 0x0e8446b3,
0x29cc5565, 0xba685c8e, 0xceb8e592, 0x5d1cec79, 0x7a54ffaf, 0xe9f0f644, 0x34c4d803,
0xa760d1e8, 0x8028c23e, 0x138ccbd5, 0xa9e4975b, 0x3a409eb0, 0x1d088d66, 0x8eac848d,
0x5398aaca, 0xc03ca321, 0xe774b0f7, 0x74d0b91c, 0x0ed5c2cf, 0x9d71cb24, 0xba39d8f2,
0x299dd119, 0xf4a9ff5e, 0x670df6b5, 0x4045e563, 0xd3e1ec88, 0x6989b006, 0xfa2db9ed,
0xdd65aa3b, 0x4ec1a3d0, 0x93f58d97, 0x0051847c, 0x271997aa, 0xb4bd9e41, 0xc06d275d,
0x53c92eb6, 0x74813d60, 0xe725348b, 0x3a111acc, 0xa9b51327, 0x8efd00f1, 0x1d59091a,
0xa7315594, 0x34955c7f, 0x13dd4fa9, 0x80794642, 0x5d4d6805, 0xcee961ee, 0xe9a17238,
0x7a057bd3, 0x1dab859e, 0x8e0f8c75, 0xa9479fa3, 0x3ae39648, 0xe7d7b80f, 0x7473b1e4,
0x533ba232, 0xc09fabd9, 0x7af7f757, 0xe953febc, 0xce1bed6a, 0x5dbfe481, 0x808bcac6,
0x132fc32d, 0x3467d0fb, 0xa7c3d910, 0xd313600c, 0x40b769e7, 0x67ff7a31, 0xf45b73da,
0x296f5d9d, 0xbacb5476, 0x9d8347a0, 0x0e274e4b, 0xb44f12c5, 0x27eb1b2e, 0x00a308f8,
0x93070113, 0x4e332f54, 0xdd9726bf, 0xfadf3569, 0x697b3c82, 0x137e4751, 0x80da4eba,
0xa7925d6c, 0x34365487, 0xe9027ac0, 0x7aa6732b, 0x5dee60fd, 0xce4a6916, 0x74223598,
0xe7863c73, 0xc0ce2fa5, 0x536a264e, 0x8e5e0809, 0x1dfa01e2, 0x3ab21234, 0xa9161bdf,
0xddc6a2c3, 0x4e62ab28, 0x692ab8fe, 0xfa8eb115, 0x27ba9f52, 0xb41e96b9, 0x9356856f,
0x00f28c84, 0xba9ad00a, 0x293ed9e1, 0x0e76ca37, 0x9dd2c3dc, 0x40e6ed9b, 0xd342e470,
0xf40af7a6, 0x67aefe4d, 0x3b570b3c, 0xa8f302d7, 0x8fbb1101, 0x1c1f18ea, 0xc12b36ad,
0x528f3f46, 0x75c72c90, 0xe663257b, 0x5c0b79f5, 0xcfaf701e, 0xe8e763c8, 0x7b436a23,
0xa6774464, 0x35d34d8f, 0x129b5e59, 0x813f57b2, 0xf5efeeae, 0x664be745, 0x4103f493,
0xd2a7fd78, 0x0f93d33f, 0x9c37dad4, 0xbb7fc902, 0x28dbc0e9, 0x92b39c67, 0x0117958c,
0x265f865a, 0xb5fb8fb1, 0x68cfa1f6, 0xfb6ba81d, 0xdc23bbcb, 0x4f87b220, 0x3582c9f3,
0xa626c018, 0x816ed3ce, 0x12cada25, 0xcffef462, 0x5c5afd89, 0x7b12ee5f, 0xe8b6e7b4,
0x52debb3a, 0xc17ab2d1, 0xe632a107, 0x7596a8ec, 0xa8a286ab, 0x3b068f40, 0x1c4e9c96,
0x8fea957d, 0xfb3a2c61, 0x689e258a, 0x4fd6365c, 0xdc723fb7, 0x014611f0, 0x92e2181b,
0xb5aa0bcd, 0x260e0226, 0x9c665ea8, 0x0fc25743, 0x288a4495, 0xbb2e4d7e, 0x661a6339,
0xf5be6ad2, 0xd2f67904, 0x415270ef, 0x26fc8ea2, 0xb5588749, 0x9210949f, 0x01b49d74,
0xdc80b333, 0x4f24bad8, 0x686ca90e, 0xfbc8a0e5, 0x41a0fc6b, 0xd204f580, 0xf54ce656,
0x66e8efbd, 0xbbdcc1fa, 0x2878c811, 0x0f30dbc7, 0x9c94d22c, 0xe8446b30, 0x7be062db,
0x5ca8710d, 0xcf0c78e6, 0x123856a1, 0x819c5f4a, 0xa6d44c9c, 0x35704577, 0x8f1819f9,
0x1cbc1012, 0x3bf403c4, 0xa8500a2f, 0x75642468, 0xe6c02d83, 0xc1883e55, 0x522c37be,
0x28294c6d, 0xbb8d4586, 0x9cc55650, 0x0f615fbb, 0xd25571fc, 0x41f17817, 0x66b96bc1,
0xf51d622a, 0x4f753ea4, 0xdcd1374f, 0xfb992499, 0x683d2d72, 0xb5090335, 0x26ad0ade,
0x01e51908, 0x924110e3, 0xe691a9ff, 0x7535a014, 0x527db3c2, 0xc1d9ba29, 0x1ced946e,
0x8f499d85, 0xa8018e53, 0x3ba587b8, 0x81cddb36, 0x1269d2dd, 0x3521c10b, 0xa685c8e0,
0x7bb1e6a7, 0xe815ef4c, 0xcf5dfc9a, 0x5cf9f571};
for (size_t i = 0; i < len; i++) {
crc = (crc << 8) ^ table[((crc >> 24) ^ data[i]) & 0xff];
}
#else
/**
* CRC table generated from polynomial 0x93a409eb CRC-32K/4.2 (*op) (Koopman)
*
* pycrc --width 32 --poly 0x93a409eb --reflect-in False --xor-in 0 --reflect-out False
* --xor-out 0 --generate table --table-idx-width 4
*/
static const uint32_t table[16] = {0x00000000, 0x93a409eb, 0xb4ec1a3d, 0x274813d6,
0xfa7c3d91, 0x69d8347a, 0x4e9027ac, 0xdd342e47,
0x675c72c9, 0xf4f87b22, 0xd3b068f4, 0x4014611f,
0x9d204f58, 0x0e8446b3, 0x29cc5565, 0xba685c8e};
for (size_t i = 0; i < len; i++) {
crc = (crc << 4) ^ table[((crc >> 28) ^ (data[i] >> 4)) & 0x0f];
crc = (crc << 4) ^ table[((crc >> 28) ^ data[i]) & 0x0f];
}
#endif
return crc;
}

1
lib/crc/crc_shell.c
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@ -32,6 +32,7 @@ static const char *const crc_types[] = {
[CRC24_PGP] = "24_pgp",
[CRC32_C] = "32_c",
[CRC32_IEEE] = "32_ieee",
[CRC32_K_4_2] = "32_k_4_2",
};
static int string_to_crc_type(const char *s)

22
tests/unit/crc/main.c
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@ -12,6 +12,28 @@
#include "../../../lib/crc/crc32c_sw.c"
#include "../../../lib/crc/crc7_sw.c"
#include "../../../lib/crc/crc24_sw.c"
#include "../../../lib/crc/crc32k_4_2_sw.c"
ZTEST(crc, test_crc32_k_4_2)
{
uint8_t test1[] = "A";
uint8_t test2[] = "123456789";
uint8_t test3[] = "Zephyr";
const uint32_t TEST2_CRC = 0x3ee83603;
zassert_equal(crc32_k_4_2_update(0xFFFFFFFF, test1, sizeof(test1) - 1), 0x2d098604);
zassert_equal(crc32_k_4_2_update(0xFFFFFFFF, test2, sizeof(test2) - 1), TEST2_CRC);
zassert_equal(crc32_k_4_2_update(0xFFFFFFFF, test3, sizeof(test3) - 1), 0xacf334b2);
/* test iteration */
uint32_t crc = 0xFFFFFFFF;
for (size_t i = 0; i < sizeof(test2) - 1; i++) {
crc = crc32_k_4_2_update(crc, &test2[i], 1);
}
zassert_equal(crc, TEST2_CRC);
}
ZTEST(crc, test_crc32c)
{

6
tests/unit/crc/testcase.yaml
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@ -3,3 +3,9 @@ tests:
tags:
- crc
type: unit
utilities.crc.table256:
tags:
- crc
type: unit
extra_configs:
- CONFIG_CRC32_K_4_2_TABLE_256=y