/*
 * Copyright 2016 Ludwig Knüpfer <ludwig.knuepfer@fu-berlin.de>
 *
 * 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 <stdint.h>

#include "embUnit/embUnit.h"

#include "checksum/crc16_ccitt.h"

#include "tests-checksum.h"

static int calc_and_compare_crc_with_update(const unsigned char *buf,
        size_t len, size_t split, uint16_t expected)
{
    uint16_t result = crc16_ccitt_calc(buf, split);

    result = crc16_ccitt_update(result, buf + split, len - split);

    return result == expected;
}

static int calc_and_compare_crc(const unsigned char *buf, size_t len,
        uint16_t expected)
{
    uint16_t result = crc16_ccitt_calc(buf, len);

    return result == expected;
}

static void test_checksum_crc16_ccitt_sequence_empty(void)
{
    unsigned char buf[] = "";
    uint16_t expect = 0x1D0F;

    TEST_ASSERT(calc_and_compare_crc(buf, sizeof(buf) - 1, expect));
    TEST_ASSERT(calc_and_compare_crc_with_update(buf, sizeof(buf) - 1,
                (sizeof(buf) - 1) / 2, expect));
}

static void test_checksum_crc16_ccitt_sequence_1a(void)
{
    unsigned char buf[] = "A";
    uint16_t expect = 0x9479;

    TEST_ASSERT(calc_and_compare_crc(buf, sizeof(buf) - 1, expect));
    TEST_ASSERT(calc_and_compare_crc_with_update(buf, sizeof(buf) - 1,
                (sizeof(buf) - 1) / 2, expect));
}

static void test_checksum_crc16_ccitt_sequence_256a(void)
{
    unsigned char buf[] = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
                          "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
                          "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
                          "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
                          "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
                          "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
                          "AAAA";
    uint16_t expect = 0xE938;

    TEST_ASSERT(calc_and_compare_crc(buf, sizeof(buf) - 1, expect));
    TEST_ASSERT(calc_and_compare_crc_with_update(buf, sizeof(buf) - 1,
                (sizeof(buf) - 1) / 2, expect));
}

static void test_checksum_crc16_ccitt_sequence_1to9(void)
{
    unsigned char buf[] = "123456789";
    uint16_t expect = 0xE5CC;

    TEST_ASSERT(calc_and_compare_crc(buf, sizeof(buf) - 1, expect));
    TEST_ASSERT(calc_and_compare_crc_with_update(buf, sizeof(buf)
                - 1, (sizeof(buf) - 1) / 2, expect));
}

static void test_checksum_crc16_ccitt_sequence_4bytes(void)
{
    unsigned char buf[] = { 0x12, 0x34, 0x56, 0x78 };
    uint16_t expect = 0xBA3C;

    TEST_ASSERT(calc_and_compare_crc(buf, sizeof(buf), expect));
    TEST_ASSERT(calc_and_compare_crc_with_update(buf, sizeof(buf),
                sizeof(buf) / 2, expect));
}

Test *tests_checksum_crc16_ccitt_tests(void)
{
    EMB_UNIT_TESTFIXTURES(fixtures) {
        /* Reference values according to
         * http://srecord.sourceforge.net/crc16-ccitt.html */
        new_TestFixture(test_checksum_crc16_ccitt_sequence_empty),
        new_TestFixture(test_checksum_crc16_ccitt_sequence_1a),
        new_TestFixture(test_checksum_crc16_ccitt_sequence_256a),
        new_TestFixture(test_checksum_crc16_ccitt_sequence_1to9),
        new_TestFixture(test_checksum_crc16_ccitt_sequence_4bytes),
    };

    EMB_UNIT_TESTCALLER(checksum_crc16_ccitt_tests, NULL, NULL, fixtures);

    return (Test *)&checksum_crc16_ccitt_tests;
}