/src/skia/third_party/externals/harfbuzz/src/hb-cache.hh

Source (jump to first uncovered line)
/*
 * Copyright © 2012  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
 */

#ifndef HB_CACHE_HH
#define HB_CACHE_HH

#include "hb.hh"


/* Implements a lockfree cache for int->int functions.
 *
 * The cache is a fixed-size array of 16-bit or 32-bit integers.
 * The key is split into two parts: the cache index and the rest.
 *
 * The cache index is used to index into the array.  The rest is used
 * to store the key and the value.
 *
 * The value is stored in the least significant bits of the integer.
 * The key is stored in the most significant bits of the integer.
 * The key is shifted by cache_bits to the left to make room for the
 * value.
 */

template <unsigned int key_bits=16,
   unsigned int value_bits=8 + 32 - key_bits,
   unsigned int cache_bits=8,
   bool thread_safe=true>
struct hb_cache_t
{
  using item_t = typename std::conditional<thread_safe,
             typename std::conditional<key_bits + value_bits - cache_bits <= 16,
                     hb_atomic_short_t,
                     hb_atomic_int_t>::type,
             typename std::conditional<key_bits + value_bits - cache_bits <= 16,
                     short,
                     int>::type
            >::type;

  static_assert ((key_bits >= cache_bits), "");
  static_assert ((key_bits + value_bits <= cache_bits + 8 * sizeof (item_t)), "");

  hb_cache_t () { clear (); }

  void clear ()
  {
    for (auto &v : values)
      v = -1;
  }

  bool get (unsigned int key, unsigned int *value) const
  {
    unsigned int k = key & ((1u<<cache_bits)-1);
    unsigned int v = values[k];
    if ((key_bits + value_bits - cache_bits == 8 * sizeof (item_t) && v == (unsigned int) -1) ||
  (v >> value_bits) != (key >> cache_bits))
      return false;
    *value = v & ((1u<<value_bits)-1);
    return true;
  }

  bool set (unsigned int key, unsigned int value)
  {
    if (unlikely ((key >> key_bits) || (value >> value_bits)))
      return false; /* Overflows */
    unsigned int k = key & ((1u<<cache_bits)-1);
    unsigned int v = ((key>>cache_bits)<<value_bits) | value;
    values[k] = v;
    return true;
  }

  private:
  item_t values[1u<<cache_bits];
};


#endif /* HB_CACHE_HH */

Line	Count	Source (jump to first uncovered line)
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		* The cache is a fixed-size array of 16-bit or 32-bit integers.
36		* The key is split into two parts: the cache index and the rest.
37		*
38		* The cache index is used to index into the array. The rest is used
39		* to store the key and the value.
40		*
41		* The value is stored in the least significant bits of the integer.
42		* The key is stored in the most significant bits of the integer.
43		* The key is shifted by cache_bits to the left to make room for the
44		* value.
45		*/
46
47		template <unsigned int key_bits=16,
48		unsigned int value_bits=8 + 32 - key_bits,
49		unsigned int cache_bits=8,
50		bool thread_safe=true>
51		struct hb_cache_t
52		{
53		using item_t = typename std::conditional<thread_safe,
54		typename std::conditional<key_bits + value_bits - cache_bits <= 16,
55		hb_atomic_short_t,
56		hb_atomic_int_t>::type,
57		typename std::conditional<key_bits + value_bits - cache_bits <= 16,
58		short,
59		int>::type
60		>::type;
61
62		static_assert ((key_bits >= cache_bits), "");
63		static_assert ((key_bits + value_bits <= cache_bits + 8 * sizeof (item_t)), "");
64
65	0	hb_cache_t () { clear (); } Unexecuted instantiation: hb_cache_t<21u, 16u, 8u, true>::hb_cache_t() Unexecuted instantiation: hb_cache_t<24u, 16u, 8u, true>::hb_cache_t() Unexecuted instantiation: hb_cache_t<21u, 3u, 8u, true>::hb_cache_t()
66
67		void clear ()
68	0	{
69	0	for (auto &v : values)
70	0	v = -1;
71	0	} Unexecuted instantiation: hb_cache_t<21u, 3u, 8u, true>::clear() Unexecuted instantiation: hb_cache_t<21u, 16u, 8u, true>::clear() Unexecuted instantiation: hb_cache_t<24u, 16u, 8u, true>::clear()
72
73		bool get (unsigned int key, unsigned int *value) const
74	0	{
75	0	unsigned int k = key & ((1u<<cache_bits)-1);
76	0	unsigned int v = values[k];
77	0	if ((key_bits + value_bits - cache_bits == 8 * sizeof (item_t) && v == (unsigned int) -1) \|\|
78	0	(v >> value_bits) != (key >> cache_bits))
79	0	return false;
80	0	*value = v & ((1u<<value_bits)-1);
81	0	return true;
82	0	} Unexecuted instantiation: hb_cache_t<21u, 16u, 8u, true>::get(unsigned int, unsigned int) const Unexecuted instantiation: hb_cache_t<21u, 3u, 8u, true>::get(unsigned int, unsigned int) const Unexecuted instantiation: hb_cache_t<24u, 16u, 8u, true>::get(unsigned int, unsigned int*) const
83
84		bool set (unsigned int key, unsigned int value)
85	0	{
86	0	if (unlikely ((key >> key_bits) \|\| (value >> value_bits)))
87	0	return false; /* Overflows */
88	0	unsigned int k = key & ((1u<<cache_bits)-1);
89	0	unsigned int v = ((key>>cache_bits)<<value_bits) \| value;
90	0	values[k] = v;
91	0	return true;
92	0	} Unexecuted instantiation: hb_cache_t<21u, 16u, 8u, true>::set(unsigned int, unsigned int) Unexecuted instantiation: hb_cache_t<21u, 3u, 8u, true>::set(unsigned int, unsigned int) Unexecuted instantiation: hb_cache_t<24u, 16u, 8u, true>::set(unsigned int, unsigned int)
93
94		private:
95		item_t values[1u<<cache_bits];
96		};
97
98
99		#endif /* HB_CACHE_HH */

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Created: 2024-05-20 07:14