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_PRIVATE_HH 28 #define HB_CACHE_PRIVATE_HH 29 30 #include "hb-private.hh" 31 32 33 /* Implements a lock-free cache for int->int functions. */ 34 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)); 40 41 inline void clear (void) 42 { 43 memset (values, 255, sizeof (values)); 44 } 45 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 } 55 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 } 65 66 private: 67 unsigned int values[1<<cache_bits]; 68 }; 69 70 typedef hb_cache_t<21, 16, 8> hb_cmap_cache_t; 71 typedef hb_cache_t<16, 24, 8> hb_advance_cache_t; 72 73 74 #endif /* HB_CACHE_PRIVATE_HH */ 75
