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// SPDX-License-Identifier: GPL-2.0
/*
* KUnits tests for CRC16.
*
* Copyright (C) 2024, LKCAMP
* Author: Vinicius Peixoto <vpeixoto@lkcamp.dev>
* Author: Fabricio Gasperin <fgasperin@lkcamp.dev>
* Author: Enzo Bertoloti <ebertoloti@lkcamp.dev>
*/
#include <kunit/test.h>
#include <linux/crc16.h>
#include <linux/prandom.h>
#define CRC16_KUNIT_DATA_SIZE 4096
#define CRC16_KUNIT_TEST_SIZE 100
#define CRC16_KUNIT_SEED 0x12345678
/**
* struct crc16_test - CRC16 test data
* @crc: initial input value to CRC16
* @start: Start index within the data buffer
* @length: Length of the data
*/
static struct crc16_test {
u16 crc;
u16 start;
u16 length;
} tests[CRC16_KUNIT_TEST_SIZE];
u8 data[CRC16_KUNIT_DATA_SIZE];
/* Naive implementation of CRC16 for validation purposes */
static inline u16 _crc16_naive_byte(u16 crc, u8 data)
{
u8 i = 0;
crc ^= (u16) data;
for (i = 0; i < 8; i++) {
if (crc & 0x01)
crc = (crc >> 1) ^ 0xa001;
else
crc = crc >> 1;
}
return crc;
}
static inline u16 _crc16_naive(u16 crc, u8 *buffer, size_t len)
{
while (len--)
crc = _crc16_naive_byte(crc, *buffer++);
return crc;
}
/* Small helper for generating pseudorandom 16-bit data */
static inline u16 _rand16(void)
{
static u32 rand = CRC16_KUNIT_SEED;
rand = next_pseudo_random32(rand);
return rand & 0xFFFF;
}
static int crc16_init_test_data(struct kunit_suite *suite)
{
size_t i;
/* Fill the data buffer with random bytes */
for (i = 0; i < CRC16_KUNIT_DATA_SIZE; i++)
data[i] = _rand16() & 0xFF;
/* Generate random test data while ensuring the random
* start + length values won't overflow the 4096-byte
* buffer (0x7FF * 2 = 0xFFE < 0x1000)
*/
for (size_t i = 0; i < CRC16_KUNIT_TEST_SIZE; i++) {
tests[i].crc = _rand16();
tests[i].start = _rand16() & 0x7FF;
tests[i].length = _rand16() & 0x7FF;
}
return 0;
}
static void crc16_test_empty(struct kunit *test)
{
u16 crc;
/* The result for empty data should be the same as the
* initial crc
*/
crc = crc16(0x00, data, 0);
KUNIT_EXPECT_EQ(test, crc, 0);
crc = crc16(0xFF, data, 0);
KUNIT_EXPECT_EQ(test, crc, 0xFF);
}
static void crc16_test_correctness(struct kunit *test)
{
size_t i;
u16 crc, crc_naive;
for (i = 0; i < CRC16_KUNIT_TEST_SIZE; i++) {
/* Compare results with the naive crc16 implementation */
crc = crc16(tests[i].crc, data + tests[i].start,
tests[i].length);
crc_naive = _crc16_naive(tests[i].crc, data + tests[i].start,
tests[i].length);
KUNIT_EXPECT_EQ(test, crc, crc_naive);
}
}
static void crc16_test_combine(struct kunit *test)
{
size_t i, j;
u16 crc, crc_naive;
/* Make sure that combining two consecutive crc16 calculations
* yields the same result as calculating the crc16 for the whole thing
*/
for (i = 0; i < CRC16_KUNIT_TEST_SIZE; i++) {
crc_naive = crc16(tests[i].crc, data + tests[i].start, tests[i].length);
for (j = 0; j < tests[i].length; j++) {
crc = crc16(tests[i].crc, data + tests[i].start, j);
crc = crc16(crc, data + tests[i].start + j, tests[i].length - j);
KUNIT_EXPECT_EQ(test, crc, crc_naive);
}
}
}
static struct kunit_case crc16_test_cases[] = {
KUNIT_CASE(crc16_test_empty),
KUNIT_CASE(crc16_test_combine),
KUNIT_CASE(crc16_test_correctness),
{},
};
static struct kunit_suite crc16_test_suite = {
.name = "crc16",
.test_cases = crc16_test_cases,
.suite_init = crc16_init_test_data,
};
kunit_test_suite(crc16_test_suite);
MODULE_AUTHOR("Fabricio Gasperin <fgasperin@lkcamp.dev>");
MODULE_AUTHOR("Vinicius Peixoto <vpeixoto@lkcamp.dev>");
MODULE_AUTHOR("Enzo Bertoloti <ebertoloti@lkcamp.dev>");
MODULE_DESCRIPTION("Unit tests for crc16");
MODULE_LICENSE("GPL");
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