diff options
Diffstat (limited to 'src/3rdparty/harfbuzz-ng/src/hb-cache.hh')
-rw-r--r-- | src/3rdparty/harfbuzz-ng/src/hb-cache.hh | 49 |
1 files changed, 34 insertions, 15 deletions
diff --git a/src/3rdparty/harfbuzz-ng/src/hb-cache.hh b/src/3rdparty/harfbuzz-ng/src/hb-cache.hh index e617b75de9..6d8a54cf10 100644 --- a/src/3rdparty/harfbuzz-ng/src/hb-cache.hh +++ b/src/3rdparty/harfbuzz-ng/src/hb-cache.hh @@ -30,29 +30,51 @@ #include "hb.hh" -/* Implements a lockfree cache for int->int functions. */ +/* Implements a lockfree cache for int->int functions. + * + * The cache is a fixed-size array of 16-bit or 32-bit integers. + * The key is split into two parts: the cache index and the rest. + * + * The cache index is used to index into the array. The rest is used + * to store the key and the value. + * + * The value is stored in the least significant bits of the integer. + * The key is stored in the most significant bits of the integer. + * The key is shifted by cache_bits to the left to make room for the + * value. + */ -template <unsigned int key_bits, unsigned int value_bits, unsigned int cache_bits> +template <unsigned int key_bits=16, + unsigned int value_bits=8 + 32 - key_bits, + unsigned int cache_bits=8, + bool thread_safe=true> struct hb_cache_t { + using item_t = typename std::conditional<thread_safe, + typename std::conditional<key_bits + value_bits - cache_bits <= 16, + hb_atomic_short_t, + hb_atomic_int_t>::type, + typename std::conditional<key_bits + value_bits - cache_bits <= 16, + short, + int>::type + >::type; + static_assert ((key_bits >= cache_bits), ""); - static_assert ((key_bits + value_bits - cache_bits <= 8 * sizeof (hb_atomic_int_t)), ""); - static_assert (sizeof (hb_atomic_int_t) == sizeof (unsigned int), ""); + static_assert ((key_bits + value_bits <= cache_bits + 8 * sizeof (item_t)), ""); - void init () { clear (); } - void fini () {} + hb_cache_t () { clear (); } void clear () { - for (unsigned i = 0; i < ARRAY_LENGTH (values); i++) - values[i].set_relaxed (-1); + for (auto &v : values) + v = -1; } bool get (unsigned int key, unsigned int *value) const { unsigned int k = key & ((1u<<cache_bits)-1); - unsigned int v = values[k].get_relaxed (); - if ((key_bits + value_bits - cache_bits == 8 * sizeof (hb_atomic_int_t) && v == (unsigned int) -1) || + unsigned int v = values[k]; + if ((key_bits + value_bits - cache_bits == 8 * sizeof (item_t) && v == (unsigned int) -1) || (v >> value_bits) != (key >> cache_bits)) return false; *value = v & ((1u<<value_bits)-1); @@ -65,16 +87,13 @@ struct hb_cache_t 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); + values[k] = v; return true; } private: - hb_atomic_int_t values[1u<<cache_bits]; + item_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 */ |