varch/doc/hash.en.md

Introduction

A Hash algorithm is an algorithm that can discretely map data of any length to data of a specified shorter length in a way that is generally irreversible.

Interface

uint32_t hash_bkdr(void *data, uint32_t size);
uint32_t hash_ap(void *data, uint32_t size);
uint32_t hash_djb(void *data, uint32_t size);
uint32_t hash_js(void *data, uint32_t size);
uint32_t hash_rs(void *data, uint32_t size);
uint32_t hash_sdbm(void *data, uint32_t size);
uint32_t hash_pjw(void *data, uint32_t size);
uint32_t hash_elf(void *data, uint32_t size);
uint32_t hash_dek(void *data, uint32_t size);
uint32_t hash_bp(void *data, uint32_t size);
uint32_t hash_fnv(void *data, uint32_t size);
uint32_t hash_jdk6(void *data, uint32_t size);

These several checksum algorithms are used in the same way. They all take the address of the data and the size of the data as parameters and return the calculated 32-bit hash value.

Testing

static void test(void)
{
	printf("hash_bkdr 0x%X\r\n", hash_bkdr("Hello", 5));
	printf("hash_ap 0x%X\r\n", hash_ap("Hello", 5));
	printf("hash_djb 0x%X\r\n", hash_djb("Hello", 5));
	printf("hash_js 0x%X\r\n", hash_js("Hello", 5));
	printf("hash_rs 0x%X\r\n", hash_rs("Hello", 5));
	printf("hash_sdbm 0x%X\r\n", hash_sdbm("Hello", 5));
	printf("hash_pjw 0x%X\r\n", hash_pjw("Hello", 5));
	printf("hash_elf 0x%X\r\n", hash_elf("Hello", 5));
	printf("hash_dek 0x%X\r\n", hash_dek("Hello", 5));
	printf("hash_bp 0x%X\r\n", hash_bp("Hello", 5));
	printf("hash_fnv 0x%X\r\n", hash_fnv("Hello", 5));
	printf("hash_jdk6 0x%X\r\n", hash_jdk6("Hello", 5));
}

Result

hash_bkdr 0x7D80646E
hash_ap 0x646C7322
hash_djb 0xD4F2079
hash_js 0x6060CD85
hash_rs 0x15794872
hash_sdbm 0x2B45B912
hash_pjw 0x4EC32F
hash_elf 0x4EC32F
hash_dek 0xEB33DEF
hash_bp 0xCBB366F
hash_fnv 0x2EA7AFEE
hash_jdk6 0x42628B2