Hash algorithms

Files
file	hash_adler32.c
	32-bit Adler hash algorithm
file	hash_crc32.c
	32-bit CRC hash algorithm
file	hash_djb2.c
	DJB2 hash algorithm
file	hash_sdbm.c
	SDBM hash algorithm
file	hash_xor8.c
	8-bit XOR hash algorithm for ASCII characters

Functions
uint32_t	adler32 (const char *s)
	32-bit Adler algorithm implementation More...
void	test_adler32 ()
	Test function for adler32. More...
uint32_t	crc32 (const char *s)
	32-bit CRC algorithm implementation More...
void	test_crc32 ()
	Test function for crc32. More...
uint64_t	djb2 (const char *s)
	DJB2 algorithm implementation. More...
void	test_djb2 (void)
	Test function for djb2. More...
uint64_t	sdbm (const char *s)
	SDBM algorithm implementation. More...
void	test_sdbm ()
	Test function for sdbm. More...
uint8_t	xor8 (const char *s)
	8-bit XOR algorithm implementation More...
void	test_xor8 ()
	Test function for xor8. More...

Detailed Description

Function Documentation

adler32()

uint32_t adler32

(

const char *

s

)

32-bit Adler algorithm implementation

Parameters

s	NULL terminated ASCII string to hash

Returns

32-bit hash result

{
    uint32_t a = 1;
    uint32_t b = 0;
    const uint32_t MODADLER = 65521;
 
    size_t i = 0;
    while (s[i] != '\0')
    {
        a = (a + s[i]) % MODADLER;
        b = (b + a) % MODADLER;
        i++;
    }
    return (b << 16) | a;
}

crc32()

uint32_t crc32

(

const char *

s

)

32-bit CRC algorithm implementation

Parameters

s	NULL terminated ASCII string to hash

Returns

32-bit hash result

{
    uint32_t crc = 0xffffffff;
    size_t i = 0;
    while (s[i] != '\0')
    {
        uint8_t byte = s[i];
        crc = crc ^ byte;
        for (uint8_t j = 8; j > 0; --j)
        {
            crc = (crc >> 1) ^ (0xEDB88320 & (-(crc & 1)));
        }
 
        i++;
    }
    return crc ^ 0xffffffff;
}

djb2()

uint64_t djb2

(

const char *

s

)

DJB2 algorithm implementation.

Parameters

s	NULL terminated string to hash

Returns

64-bit hash result

{
    uint64_t hash = 5381; /* init value */
    size_t i = 0;
    while (s[i] != '\0')
    {
        hash = ((hash << 5) + hash) + s[i];
        i++;
    }
    return hash;
}

sdbm()

uint64_t sdbm

(

const char *

s

)

SDBM algorithm implementation.

Parameters

s	NULL terminated string to hash

Returns

64-bit hash result

{
    uint64_t hash = 0;
    size_t i = 0;
    while (s[i] != '\0')
    {
        hash = s[i] + (hash << 6) + (hash << 16) - hash;
        i++;
    }
    return hash;
}

test_adler32()

void test_adler32

(

)

Test function for adler32.

Returns

None

{
    assert(adler32("Hello World") == 403375133);
    assert(adler32("Hello World!") == 474547262);
    assert(adler32("Hello world") == 413860925);
    assert(adler32("Hello world!") == 487130206);
    printf("Tests passed\n");
}

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test_crc32()

void test_crc32

(

)

Test function for crc32.

Returns

None

{
    assert(crc32("Hello World") == 1243066710);
    assert(crc32("Hello World!") == 472456355);
    assert(crc32("Hello world") == 2346098258);
    assert(crc32("Hello world!") == 461707669);
    printf("Tests passed\n");
}

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test_djb2()

void test_djb2

(

void

)

Test function for djb2.

Returns

none

{
    assert(djb2("Hello World") == 13827776004929097857);
    assert(djb2("Hello World!") == 13594750393630990530);
    assert(djb2("Hello world") == 13827776004967047329);
    assert(djb2("Hello world!") == 13594750394883323106);
    printf("Tests passed\n");
}

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test_sdbm()

void test_sdbm

(

)

Test function for sdbm.

Returns

None

{
    assert(sdbm("Hello World") == 12881824461405877380U);
    assert(sdbm("Hello World!") == 7903571203300273309);
    assert(sdbm("Hello world") == 15154913742888948900U);
    assert(sdbm("Hello world!") == 15254999417003201661U);
    printf("Tests passed\n");
}

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test_xor8()

void test_xor8

(

)

Test function for xor8.

Returns

None

{
    assert(xor8("Hello World") == 228);
    assert(xor8("Hello World!") == 195);
    assert(xor8("Hello world") == 196);
    assert(xor8("Hello world!") == 163);
    printf("Tests passed\n");
}

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xor8()

uint8_t xor8

(

const char *

s

)

8-bit XOR algorithm implementation

Parameters

s	NULL terminated ASCII string to hash

Returns

8-bit hash result

{
    uint8_t hash = 0;
    size_t i = 0;
    while (s[i] != '\0')
    {
        hash = (hash + s[i]) & 0xff;
        i++;
    }
    return (((hash ^ 0xff) + 1) & 0xff);
}