84 lines
2.2 KiB
C++
84 lines
2.2 KiB
C++
/*
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* Copyright © 2018 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* Google Author(s): Behdad Esfahbod
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*/
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#include "hb-private.hh"
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#ifndef HB_NO_VISIBILITY
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void * const _hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
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/*thread_local*/ void * _hb_CrapPool[HB_NULL_POOL_SIZE / sizeof (void *)] = {};
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#endif
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/* Following comment and table copied from glib. */
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/* Each table size has an associated prime modulo (the first prime
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* lower than the table size) used to find the initial bucket. Probing
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* then works modulo 2^n. The prime modulo is necessary to get a
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* good distribution with poor hash functions.
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*/
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static const unsigned int prime_mod [] =
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{
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1, /* For 1 << 0 */
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2,
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3,
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7,
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13,
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31,
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61,
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127,
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251,
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509,
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1021,
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2039,
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4093,
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8191,
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16381,
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32749,
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65521, /* For 1 << 16 */
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131071,
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262139,
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524287,
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1048573,
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2097143,
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4194301,
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8388593,
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16777213,
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33554393,
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67108859,
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134217689,
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268435399,
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536870909,
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1073741789,
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2147483647 /* For 1 << 31 */
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};
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unsigned int _hb_prime_for (unsigned int shift)
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{
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if (unlikely (shift >= ARRAY_LENGTH (prime_mod)))
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return prime_mod[ARRAY_LENGTH (prime_mod) - 1];
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return prime_mod[shift];
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}
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