Merge pull request #18686 from benpicco/checksum/crc32

sys/checksum: add CRC-32 checksum

dist/tools/codespell/ignored_words.txt

@@ -147,3 +147,6 @@ nam
 
 # donot (part of bloom filter test vector) => do not
 donot
+
+# Didi (Ayman El Didi) => Did
+didi

makefiles/pseudomodules.inc.mk

@@ -45,6 +45,7 @@ PSEUDOMODULES += cortexm_fpu
 PSEUDOMODULES += cortexm_svc
 PSEUDOMODULES += cpp
 PSEUDOMODULES += cpu_check_address
+PSEUDOMODULES += crc32_fast
 PSEUDOMODULES += credman_load
 PSEUDOMODULES += dbgpin
 PSEUDOMODULES += devfs_%

sys/Makefile.dep

@@ -49,6 +49,10 @@ ifneq (,$(filter congure_reno_methods,$(USEMODULE)))
   USEMODULE += seq
 endif
 
+ifneq (,$(filter crc32_fast,$(USEMODULE)))
+  USEMODULE += checksum
+endif
+
 ifneq (,$(filter eepreg,$(USEMODULE)))
   FEATURES_REQUIRED += periph_eeprom
 endif

sys/checksum/crc32.c

@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2020 Ayman El Didi
+ *
+ * To the extent possible under law, the author(s) have dedicated all
+ * domain worldwide. This software is distributed without any warranty.
+ *
+ * You should have received a copy of the CC0 Public Domain Dedication along
+ * with this software. If not, see http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+/**
+ * @{
+ *
+ * @file
+ * @author      Ayman El Didi <ayman@eldidi.org>
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ */
+
+#include "kernel_defines.h"
+#include "checksum/crc32.h"
+
+const uint32_t crc32_tab[] = {
+    0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
+    0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
+    0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
+    0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
+    0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
+    0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
+    0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
+    0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
+    0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
+    0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+    0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
+    0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
+    0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
+    0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
+    0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
+    0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
+    0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
+    0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
+    0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
+    0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+    0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
+    0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
+    0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
+    0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
+    0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
+    0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
+    0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
+    0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
+    0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
+    0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+    0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
+    0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
+    0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
+    0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
+    0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
+    0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
+    0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
+    0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
+    0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
+    0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+    0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
+    0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
+    0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
+};
+
+static inline uint32_t crc32_for_byte(uint32_t result)
+{
+    if (IS_USED(MODULE_CRC32_FAST)) {
+        return crc32_tab[result & 0xFF] ^ (result >> 8);
+    }
+
+    const uint32_t polynomial = 0xEDB88320L;
+
+    for (unsigned i = 0; i < 8; i++) {
+        /* IMPLEMENTATION: the code below always shifts result right by
+         * 1, but only XORs it by the polynomial if we're on the lowest
+         * bit.
+         *
+         * This is because 1 in binary is 00000001, so ANDing the
+         * result by 1 will always give 0 unless the lowest bit is set.
+         * And since XOR by zero does nothing, the other half only
+         * occurs when we're on the lowest bit.
+         *
+         * I didn't leave the above implementation in, despite being
+         * faster on my machine since it is a more complex operation
+         * which may be slower on less sophisticated processors. It can
+         * be added in in place of the loop code below.
+         */
+
+        result = (result >> 1) ^ (result & 1) * polynomial;
+
+        /* Here is the code I replaced with the branch I tried to
+         * remove:
+        if (result & 1) {
+            result = (result >> 1) ^ polynomial;
+            continue;
+        }
+        result >>= 1;
+         */
+    }
+    return result;
+}
+
+uint32_t crc32(const void *buf, size_t size)
+{
+    const uint8_t *p = buf;
+    uint32_t crc = ~0U;
+
+    for (unsigned i = 0; i < size; ++i) {
+        crc ^= *p++;
+        crc = crc32_for_byte(crc);
+
+    }
+
+    return ~crc;
+}
+
+/** @} */

sys/include/checksum/crc32.h

@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2022 ML!PA Consulting GmbH
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @defgroup    sys_checksum_crc32 CRC32
+ * @ingroup     sys_checksum
+ *
+ * @brief       CRC32 checksum algorithm implementation according to IEEE standards
+ * @{
+ *
+ * @file
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ */
+
+#ifndef CHECKSUM_CRC32_H
+#define CHECKSUM_CRC32_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   CRC-32 checksum
+ *
+ * Uses the `0xedb88320` polynomial
+ *
+ * @note enable the `crc32_fast` module for a look-up table based implementation
+ *       that trades code size for speed.
+ *
+ * @param[in] buf   The data to checksum
+ * @param[in] size  Length of the data in bytes
+ *
+ * @return 32 bit sized hash in the interval [0..2^32]
+ */
+uint32_t crc32(const void *buf, size_t size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* CHECKSUM_CRC32_H */
+
+/** @} */

tests/unittests/tests-checksum/tests-checksum-crc32.c

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2022 Benjamin Valentin <benpicco@googlemail.com>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+#include "checksum/crc32.h"
+#include "tests-checksum.h"
+
+static void test_checksum_crc32_sequence_empty(void)
+{
+    unsigned char buf[] = "";
+    uint32_t expect = 0x0;
+
+    TEST_ASSERT_EQUAL_INT(expect, crc32(buf, sizeof(buf) - 1));
+}
+
+static void test_checksum_crc32_sequence_1a(void)
+{
+    unsigned char buf[] = "A";
+    uint32_t expect = 0xd3d99e8b;
+
+    TEST_ASSERT_EQUAL_INT(expect, crc32(buf, sizeof(buf) - 1));
+}
+
+static void test_checksum_crc32_sequence_256a(void)
+{
+    unsigned char buf[] = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+                          "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+                          "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+                          "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+                          "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+                          "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+                          "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+                          "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
+    uint32_t expect = 0x49975b13;
+
+    TEST_ASSERT_EQUAL_INT(expect, crc32(buf, sizeof(buf) - 1));
+}
+
+static void test_checksum_crc32_sequence_1to9(void)
+{
+    unsigned char buf[] = "123456789";
+    uint32_t expect = 0xcbf43926;
+
+    TEST_ASSERT_EQUAL_INT(expect, crc32(buf, sizeof(buf) - 1));
+}
+
+static void test_checksum_crc32_sequence_4bytes(void)
+{
+    unsigned char buf[] = { 0x12, 0x34, 0x56, 0x78 };
+    uint32_t expect = 0x4a090e98;
+
+    TEST_ASSERT_EQUAL_INT(expect, crc32(buf, sizeof(buf)));
+}
+
+Test *tests_checksum_crc32_tests(void)
+{
+    EMB_UNIT_TESTFIXTURES(fixtures) {
+        new_TestFixture(test_checksum_crc32_sequence_empty),
+        new_TestFixture(test_checksum_crc32_sequence_1a),
+        new_TestFixture(test_checksum_crc32_sequence_256a),
+        new_TestFixture(test_checksum_crc32_sequence_1to9),
+        new_TestFixture(test_checksum_crc32_sequence_4bytes),
+    };
+
+    EMB_UNIT_TESTCALLER(checksum_crc32_tests, NULL, NULL, fixtures);
+
+    return (Test *)&checksum_crc32_tests;
+}

tests/unittests/tests-checksum/tests-checksum.c

@@ -15,6 +15,7 @@ void tests_checksum(void)
     TESTS_RUN(tests_checksum_crc16_ccitt_mcrf4xx_tests());
     TESTS_RUN(tests_checksum_crc16_ccitt_aug_tests());
     TESTS_RUN(tests_checksum_crc16_ccitt_false_tests());
+    TESTS_RUN(tests_checksum_crc32_tests());
     TESTS_RUN(tests_checksum_fletcher16_tests());
     TESTS_RUN(tests_checksum_fletcher32_tests());
     TESTS_RUN(tests_checksum_ucrc16_tests());

tests/unittests/tests-checksum/tests-checksum.h

@@ -64,6 +64,13 @@ Test *tests_checksum_crc16_ccitt_false_tests(void);
  */
 Test *tests_checksum_crc16_ccitt_aug_tests(void);
 
+/**
+ * @brief   Generates tests for checksum/crc32.h
+ *
+ * @return  embUnit tests if successful, NULL if not.
+ */
+Test *tests_checksum_crc32_tests(void);
+
 /**
  * @brief   Generates tests for checksum/fletcher16.h
  *