Revert "Remove unused hb_cache_t"

This reverts commit 473b17af.

Updates to recent changes.

src/Makefile.sources

@@ -7,6 +7,7 @@ HB_BASE_sources = \
 	hb-buffer.hh \
 	hb-buffer-serialize.cc \
 	hb-buffer.cc \
+	hb-cache.hh \
 	hb-common.cc \
 	hb-debug.hh \
 	hb-dsalgs.hh \

src/hb-cache.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_HH
+#define HB_CACHE_HH
+
+#include "hb.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
+{
+  static_assert ((key_bits >= cache_bits), "");
+  static_assert ((key_bits + value_bits - cache_bits < 8 * sizeof (unsigned int)), "");
+
+  inline void init (void) { clear (); }
+  inline void fini (void) {}
+
+  inline void clear (void)
+  { memset (values, 255, sizeof (values)); }
+
+  inline bool get (unsigned int key, unsigned int *value)
+  {
+    unsigned int k = key & ((1u<<cache_bits)-1);
+    unsigned int v = values[k].get_relaxed ();
+    if ((v >> value_bits) != (key >> cache_bits))
+      return false;
+    *value = v & ((1u<<value_bits)-1);
+    return true;
+  }
+
+  inline 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].set_relaxed (v);
+    return true;
+  }
+
+  private:
+  hb_atomic_int_t values[1u<<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_HH */

src/hb-ft.cc

@@ -33,6 +33,7 @@
 
 #include "hb-font.hh"
 #include "hb-machinery.hh"
+#include "hb-cache.hh"
 
 #include FT_ADVANCES_H
 #include FT_MULTIPLE_MASTERS_H