add fnv32_1 implementation

master
orange 12 years ago
parent 697f7dfd27
commit 896478de2d

1
.gitignore vendored

@ -13,3 +13,4 @@ ncurses-pong
checkcheck
multibrot
multibrot.png
bloom

@ -1,7 +1,7 @@
CFLAGS=-std=c99 -Wall -g -O2
INDENTOPTS=-kr --no-tabs --braces-on-func-def-line --indent-level2
TARGETS=approximate-pi linked-list mandelbrot threads circular-buffer structs ncurses-pong bit-fuckery bit-fuckery2 checkcheck multibrot
TARGETS=approximate-pi linked-list mandelbrot threads circular-buffer structs ncurses-pong bit-fuckery bit-fuckery2 checkcheck multibrot bloom
EXTRAS=mandelbrot.bmp multibrot.png
.PHONY: all

@ -0,0 +1,46 @@
#include <assert.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
/*
* FNV-1 hash implementation (32-bit aka FNV32_1).
*
* See http://isthe.com/chongo/tech/comp/fnv/
*/
uint32_t fnv32_1(uint8_t *data, size_t data_len) {
uint32_t hash;
/* Constants, for 32-bit only. */
uint32_t offset_basis = (uint32_t) 2166136261UL;
uint32_t FNV_prime = (uint32_t) 16777619UL;
hash = offset_basis;
for (size_t i = 0; i < data_len; i++) {
hash = hash * FNV_prime; /* implictly modulo 2^32 */
hash = hash ^ data[i]; /* implictly only on lower octet. */
}
return hash;
}
/* Compute FNV-1 hash for the given string (without NUL byte). */
uint32_t fnv32_1_str(char *string) {
return fnv32_1((uint8_t *) string, strlen(string));
}
int main(void) {
/* Test FNV32_1 */
assert(fnv32_1_str("03SB[") == 0x00000000UL);
assert(fnv32_1_str("") == 0x811c9dc5UL);
assert(fnv32_1_str("a") == 0x050c5d7eUL);
assert(fnv32_1_str("b") == 0x050c5d7dUL);
assert(fnv32_1_str("c") == 0x050c5d7cUL);
assert(fnv32_1_str("d") == 0x050c5d7bUL);
assert(fnv32_1_str("e") == 0x050c5d7aUL);
assert(fnv32_1_str("f") == 0x050c5d79UL);
assert(fnv32_1_str("fo") == 0x6b772514UL);
assert(fnv32_1_str("foo") == 0x408f5e13UL);
assert(fnv32_1_str("foob") == 0xb4b1178bUL);
assert(fnv32_1_str("fooba") == 0xfdc80fb0UL);
assert(fnv32_1_str("foobar") == 0x31f0b262UL);
}
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