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comparison mupdf-source/thirdparty/harfbuzz/src/hb-cache.hh @ 3:2c135c81b16c

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MERGE: upstream PyMuPDF 1.26.4 with MuPDF 1.26.7
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:44:09 +0200
parents b50eed0cc0ef
children
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0:6015a75abc2d 3:2c135c81b16c
1 /*
2 * Copyright © 2012 Google, Inc.
3 *
4 * This is part of HarfBuzz, a text shaping library.
5 *
6 * Permission is hereby granted, without written agreement and without
7 * license or royalty fees, to use, copy, modify, and distribute this
8 * software and its documentation for any purpose, provided that the
9 * above copyright notice and the following two paragraphs appear in
10 * all copies of this software.
11 *
12 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
13 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
14 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
15 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
16 * DAMAGE.
17 *
18 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
19 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
21 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
22 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
23 *
24 * Google Author(s): Behdad Esfahbod
25 */
26
27 #ifndef HB_CACHE_HH
28 #define HB_CACHE_HH
29
30 #include "hb.hh"
31
32
33 /* Implements a lockfree cache for int->int functions. */
34
35 template <unsigned int key_bits=16,
36 unsigned int value_bits=8 + 32 - key_bits,
37 unsigned int cache_bits=8,
38 bool thread_safe=true>
39 struct hb_cache_t
40 {
41 using item_t = typename std::conditional<thread_safe,
42 hb_atomic_int_t,
43 typename std::conditional<key_bits + value_bits - cache_bits <= 16,
44 short,
45 int>::type
46 >::type;
47
48 static_assert ((key_bits >= cache_bits), "");
49 static_assert ((key_bits + value_bits <= cache_bits + 8 * sizeof (item_t)), "");
50
51 void init () { clear (); }
52 void fini () {}
53
54 void clear ()
55 {
56 for (unsigned i = 0; i < ARRAY_LENGTH (values); i++)
57 values[i] = -1;
58 }
59
60 bool get (unsigned int key, unsigned int *value) const
61 {
62 unsigned int k = key & ((1u<<cache_bits)-1);
63 unsigned int v = values[k];
64 if ((key_bits + value_bits - cache_bits == 8 * sizeof (item_t) && v == (unsigned int) -1) ||
65 (v >> value_bits) != (key >> cache_bits))
66 return false;
67 *value = v & ((1u<<value_bits)-1);
68 return true;
69 }
70
71 bool set (unsigned int key, unsigned int value)
72 {
73 if (unlikely ((key >> key_bits) || (value >> value_bits)))
74 return false; /* Overflows */
75 unsigned int k = key & ((1u<<cache_bits)-1);
76 unsigned int v = ((key>>cache_bits)<<value_bits) | value;
77 values[k] = v;
78 return true;
79 }
80
81 private:
82 item_t values[1u<<cache_bits];
83 };
84
85
86 #endif /* HB_CACHE_HH */