Roll harfbuzz-ng 3b8fd9c48f4bde368bf2d465c148b9743a9216ee

third_party/harfbuzz-ng/src/hb-cache-private.hh

+/*
+ * 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_PRIVATE_HH
+#define HB_CACHE_PRIVATE_HH
+
+#include "hb-private.hh"
+
+
+/* Implements a lock-free cache for int->int functions. */
+
+template <unsigned int key_bits, unsigned int value_bits, unsigned int cache_bits>
+struct hb_cache_t
+{
+  ASSERT_STATIC (key_bits >= cache_bits);
+  ASSERT_STATIC (key_bits + value_bits - cache_bits < 8 * sizeof (unsigned int));
+
+  inline void clear (void)
+  {
+    memset (values, 255, sizeof (values));
+  }
+
+  inline bool get (unsigned int key, unsigned int *value)
+  {
+    unsigned int k = key & ((1<<cache_bits)-1);
+    unsigned int v = values[k];
+    if ((v >> value_bits) != (key >> cache_bits))
+      return false;
+  }
+
+  inline bool set (unsigned int key, unsigned int value)
+  {
+    if (unlikely ((key >> key_bits) || (value >> value_bits)))
+      return false; /* Overflows */
+    unsigned int k = key & ((1<<cache_bits)-1);
+    unsigned int v = ((key>>cache_bits)<<value_bits) | value;
+    values[k] = v;
+    return true;
+  }
+
+  private:
+  unsigned int values[1<<cache_bits];
+};
+
+typedef hb_cache_t<21, 16, 8> hb_cmap_cache_t;
+typedef hb_cache_t<16, 24, 8> hb_advance_cache_t;
+
+
+#endif /* HB_CACHE_PRIVATE_HH */