hash.c


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#include "internal.h"

//
// hash functions (djb2)
// (see http://aras-p.info/blog/2016/08/02/Hash-Functions-all-the-way-down/)
//

uint32_t
fhp_hash_init(void) {
  return 5381;
}

uint32_t
fhp_hash_push(uint32_t hash, uint8_t * const buf, size_t len) {
  for (size_t i = 0; i < len; i++)
    hash = ((hash << 5) + hash) + buf[i];

  return hash;
}

uint32_t
fhp_hash_string(char * const str) {
  uint32_t r = fhp_hash_init();
  return fhp_hash_push(r, (uint8_t*) str, strlen(str));
}

uint32_t
fhp_lc_hash_push(
  uint32_t hash,
  uint8_t * const buf,
  size_t len
) {
  for (size_t i = 0; i < len; i++) {
    uint8_t c = buf[i];

    if ((c >= 'A') && (c <= 'Z'))
      c = (c - 'A') + 'a';

    hash = ((hash << 5) + hash) + c;
  }

  return hash;
}

uint32_t
fhp_lc_hash_string(char * const str) {
  uint32_t r = fhp_hash_init();
  return fhp_lc_hash_push(r, (uint8_t*) str, strlen(str));
}