/* ============================================================================
//
// = LIBRARY
//    ULib - c library
//
// = FILENAME
//    hash.h
//
// = AUTHOR
//    Stefano Casazza
//
// ============================================================================ */

#ifndef ULIB_BASE_HASH_H
#define ULIB_BASE_HASH_H 1

#include <ulib/base/xxhash/xxhash.h>

#undef GCC_VERSION
#include <ulib/base/base.h>

/* get next prime number for container */
#define U_GET_NEXT_PRIME_NUMBER(sz) \
 ((sz) <=         53U ?         97U : \
  (sz) <=         97U ?        193U : \
  (sz) <=        193U ?        389U : \
  (sz) <=        389U ?        769U : \
  (sz) <=        769U ?       1543U : \
  (sz) <=       1543U ?       3079U : \
  (sz) <=       3079U ?       6151U : \
  (sz) <=       6151U ?      12289U : \
  (sz) <=      12289U ?      24593U : \
  (sz) <=      24593U ?      49157U : \
  (sz) <=      49157U ?      98317U : \
  (sz) <=      98317U ?     196613U : \
  (sz) <=     196613U ?     393241U : \
  (sz) <=     393241U ?     786433U : \
  (sz) <=     786433U ?    1572869U : \
  (sz) <=    1572869U ?    3145739U : \
  (sz) <=    3145739U ?    6291469U : \
  (sz) <=    6291469U ?   12582917U : \
  (sz) <=   12582917U ?   25165843U : \
  (sz) <=   25165843U ?   50331653U : \
  (sz) <=   50331653U ?  100663319U : \
  (sz) <=  100663319U ?  201326611U : \
  (sz) <=  201326611U ?  402653189U : \
  (sz) <=  402653189U ?  805306457U : \
  (sz) <=  805306457U ?  805306457U : \
  (sz) <= 1610612741U ? 3221225473U : 4294967291U)

#ifdef __cplusplus
extern "C" {
#endif

/* hash variable-length key into 32-bit value */

static inline uint32_t u_xxhash32(const unsigned char* restrict t, uint32_t tlen) { return XXH32(t, tlen, u_seed_hash); }
static inline uint32_t u_xxhash64(const unsigned char* restrict t, uint32_t tlen)
   { return (uint32_t)(((XXH64(t, tlen, u_seed_hash) * (1578233944ULL << 32 | 194370989ULL)) + (20591ULL << 16)) >> 32); }

#ifndef USE_HARDWARE_CRC32
static inline uint32_t u_hash(const unsigned char* restrict t, uint32_t tlen) { return XXH32(t, tlen, u_seed_hash); }
#else
static inline uint32_t u_crc32(const unsigned char* restrict bp, uint32_t len)
{
   uint32_t h1 = 0xABAD1DEA;

   U_INTERNAL_TRACE("u_crc32(%.*s,%u)", U_min(len,128), bp, len)

# ifdef HAVE_ARCH64
   while (len >= sizeof(uint64_t))
      {
      h1 = __builtin_ia32_crc32di(h1, u_get_unalignedp64(bp));

      bp  += sizeof(uint64_t);
      len -= sizeof(uint64_t);
      }
# endif
   while (len >= sizeof(uint32_t))
      {
      h1 = __builtin_ia32_crc32si(h1, u_get_unalignedp32(bp));

      bp  += sizeof(uint32_t);
      len -= sizeof(uint32_t);
      }

   if (len >= sizeof(uint16_t))
      {
      h1 = __builtin_ia32_crc32hi(h1, u_get_unalignedp16(bp));

      bp  += sizeof(uint16_t);
      len -= sizeof(uint16_t);
      }

   if (len) h1 = __builtin_ia32_crc32qi(h1, *bp);

   U_INTERNAL_PRINT("h1 = %u", h1)

   U_INTERNAL_ASSERT_MAJOR(h1, 0)

   return h1;
}

static inline uint32_t u_hash(const unsigned char* restrict t, uint32_t tlen) { return u_crc32(t, tlen); }
#endif

U_EXPORT uint32_t u_hash_ignore_case(const unsigned char* restrict t, uint32_t tlen) __pure;

U_EXPORT uint32_t u_cdb_hash(const unsigned char* restrict t, uint32_t tlen, int flags) __pure;

U_EXPORT uint32_t u_random(uint32_t val) __pure; /* quick 4byte hashing function */
U_EXPORT uint32_t u_integerHash(uint32_t val) __pure;
#ifdef HAVE_ARCH64
U_EXPORT uint32_t u_random64(uint64_t ptr) __pure;
#endif
static inline double u_randomd(uint32_t a) { return (1.0/4294967296.0) * u_random(a); } /* Map hash value into number 0.0 <= n < 1.0 */

#ifdef __cplusplus
}
#endif

#endif