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116 lines
2.5 KiB
116 lines
2.5 KiB
#include <stdlib.h>
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#include <stdint.h>
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#include <stdio.h>
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#include "utils.h"
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#define DELTA 0x2
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#define OVERSHOOT 0x8
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err_t _array_rescale(void ***ptr, size_t *len, size_t use)
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{
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CHECK(len, INVALID_PARAMS)
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CHECK((use <= *len), INVALID_PARAMS)
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CHECK(ptr, INVALID_PARAMS)
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// This is a simple linear scale strategy
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if ((int) (*len - OVERSHOOT) >= (int) (use + DELTA)) *len -= OVERSHOOT;
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if (use + DELTA >= *len) *len += DELTA;
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*ptr = realloc(*ptr, *len * sizeof(void *));
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return OK;
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}
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err_t _array_search(void **ptr, size_t len, size_t *out, void *in)
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{
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CHECK(ptr, INVALID_PARAMS)
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CHECK(in, INVALID_PARAMS)
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CHECK((len > 0), INVALID_PARAMS)
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(*out) = -1;
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for(int i = 0; i < len; i++)
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if((*ptr) == in) (*out) = i;
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return OK;
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}
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err_t _array_remove(void **ptr, size_t idx, size_t len, void **out)
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{
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CHECK(ptr, INVALID_PARAMS)
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CHECK((idx >= 0), INVALID_PARAMS)
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CHECK((len > idx), INVALID_PARAMS)
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if(out != NULL) (*out) = ptr[idx];
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for(int i = idx + 1; idx < len; i++)
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ptr[i - 1] = ptr[i];
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return OK;
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}
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err_t _hash(char *str, size_t len, size_t *out)
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{
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CHECK(str, INVALID_PARAMS)
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CHECK((len > 0), INVALID_PARAMS)
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// Implements the "murmur" non-cryptographic hash
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#define C1 0xcc9e2d51
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#define C2 0x1b873593
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#define N 0xe6546b64
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#define M 5
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#define C3 0x85ebca6b
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#define C4 0xc2b2ae35
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#define R1 15
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#define R2 13
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#define R3 16
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#define R4 13
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#define ROTL32(v, shift) ( ((v) << (shift)) | ( (v) >> (32 - (shift))) )
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size_t key_len = strlen(str);
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int l = (int) key_len / 4;
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uint32_t seed = 0xAF172FE;
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int i = 0;
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uint32_t k = 0;
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uint32_t h = seed;
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uint8_t *d = (uint8_t *) str;
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const uint32_t *chunks = (const uint32_t *)(d + l * 4);
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const uint8_t *tail = (const uint8_t *)(d + l * 4);
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for (i = -l; i != 0; ++i) {
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k = chunks[i];
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k *= C1;
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k = ROTL32(k, R1);
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k *= C2;
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h ^= k;
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h = ROTL32(k, R2);
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h = h * M + N;
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}
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k = 0;
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switch(key_len & 3) {
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case 3:
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k ^= (tail[2] << 16);
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case 2:
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k ^= (tail[1] << 8);
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case 1:
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k ^= tail[0];
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k *= C1;
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k = ROTL32(k, R1);
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k *= C2;
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h ^= k;
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default: break;
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}
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/* Finalised hash */
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h ^= key_len;
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h ^= (h >> R3);
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h *= C3;
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h ^= (h >> R4);
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h *= C4;
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h ^= (h >> R3);
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/* Finalise ✨ */
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h %= len;
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*out = (size_t) h;
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return OK;
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}
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