The Tor Browser: gfx/harfbuzz/src/hb-cache-private.hh@925c144e1f1f

     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  */

    27 #ifndef HB_CACHE_PRIVATE_HH

    28 #define HB_CACHE_PRIVATE_HH

    30 #include "hb-private.hh"

    33 /* Implements a lock-free cache for int->int functions. */

    35 template <unsigned int key_bits, unsigned int value_bits, unsigned int cache_bits>

    36 struct hb_cache_t

    37 {

    38   ASSERT_STATIC (key_bits >= cache_bits);

    39   ASSERT_STATIC (key_bits + value_bits - cache_bits < 8 * sizeof (unsigned int));

    41   inline void clear (void)

    42   {

    43     memset (values, 255, sizeof (values));

    44   }

    46   inline bool get (unsigned int key, unsigned int *value)

    47   {

    48     unsigned int k = key & ((1<<cache_bits)-1);

    49     unsigned int v = values[k];

    50     if ((v >> value_bits) != (key >> cache_bits))

    51       return false;

    52     *value = v & ((1<<value_bits)-1);

    53     return true;

    54   }

    56   inline bool set (unsigned int key, unsigned int value)

    57   {

    58     if (unlikely ((key >> key_bits) || (value >> value_bits)))

    59       return false; /* Overflows */

    60     unsigned int k = key & ((1<<cache_bits)-1);

    61     unsigned int v = ((key>>cache_bits)<<value_bits) | value;

    62     values[k] = v;

    63     return true;

    64   }

    66   private:

    67   unsigned int values[1<<cache_bits];

    68 };

    70 typedef hb_cache_t<21, 16, 8> hb_cmap_cache_t;

    71 typedef hb_cache_t<16, 24, 8> hb_advance_cache_t;

    74 #endif /* HB_CACHE_PRIVATE_HH */

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