src/hb-static.cc

/*
 * Copyright © 2018  Google, Inc.
 *
 *  This is part of HarfBuzz, a text shaping library.
 *
 * Permission is hereby granted, without written agreement and without
 * license or royalty fees, to use, copy, modify, and distribute this
 * software and its documentation for any purpose, provided that the
 * above copyright notice and the following two paragraphs appear in
 * all copies of this software.
 *
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 *
 * Google Author(s): Behdad Esfahbod
 */

#include "hb-private.hh"

#ifndef HB_NO_VISIBILITY
void * const _hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
/*thread_local*/ void * _hb_CrapPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
#endif


/* Following comment and table copied from glib. */
/* Each table size has an associated prime modulo (the first prime
 * lower than the table size) used to find the initial bucket. Probing
 * then works modulo 2^n. The prime modulo is necessary to get a
 * good distribution with poor hash functions.
 */
static const unsigned int prime_mod [] =
{
  1,          /* For 1 << 0 */
  2,
  3,
  7,
  13,
  31,
  61,
  127,
  251,
  509,
  1021,
  2039,
  4093,
  8191,
  16381,
  32749,
  65521,      /* For 1 << 16 */
  131071,
  262139,
  524287,
  1048573,
  2097143,
  4194301,
  8388593,
  16777213,
  33554393,
  67108859,
  134217689,
  268435399,
  536870909,
  1073741789,
  2147483647  /* For 1 << 31 */
};

unsigned int _hb_prime_for (unsigned int shift)
{
  if (unlikely (shift >= ARRAY_LENGTH (prime_mod)))
    return prime_mod[ARRAY_LENGTH (prime_mod) - 1];

  return prime_mod[shift];
}