HarfBuzz text shaping engine
http://harfbuzz.github.io/
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80 lines
2.5 KiB
80 lines
2.5 KiB
/* |
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* Copyright © 2012 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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#ifndef HB_CACHE_HH |
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#define HB_CACHE_HH |
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#include "hb.hh" |
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/* Implements a lock-free cache for int->int functions. */ |
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template <unsigned int key_bits, unsigned int value_bits, unsigned int cache_bits> |
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struct hb_cache_t |
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{ |
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static_assert ((key_bits >= cache_bits), ""); |
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static_assert ((key_bits + value_bits - cache_bits <= 8 * sizeof (hb_atomic_int_t)), ""); |
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static_assert (sizeof (hb_atomic_int_t) == sizeof (unsigned int), ""); |
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void init () { clear (); } |
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void fini () {} |
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void clear () |
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{ |
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for (unsigned i = 0; i < ARRAY_LENGTH (values); i++) |
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values[i].set_relaxed (-1); |
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} |
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bool get (unsigned int key, unsigned int *value) const |
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{ |
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unsigned int k = key & ((1u<<cache_bits)-1); |
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unsigned int v = values[k].get_relaxed (); |
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if ((key_bits + value_bits - cache_bits == 8 * sizeof (hb_atomic_int_t) && v == (unsigned int) -1) || |
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(v >> value_bits) != (key >> cache_bits)) |
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return false; |
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*value = v & ((1u<<value_bits)-1); |
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return true; |
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} |
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bool set (unsigned int key, unsigned int value) |
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{ |
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if (unlikely ((key >> key_bits) || (value >> value_bits))) |
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return false; /* Overflows */ |
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unsigned int k = key & ((1u<<cache_bits)-1); |
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unsigned int v = ((key>>cache_bits)<<value_bits) | value; |
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values[k].set_relaxed (v); |
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return true; |
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} |
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private: |
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hb_atomic_int_t values[1u<<cache_bits]; |
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}; |
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typedef hb_cache_t<21, 16, 8> hb_cmap_cache_t; |
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typedef hb_cache_t<16, 24, 8> hb_advance_cache_t; |
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#endif /* HB_CACHE_HH */
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