diff options
Diffstat (limited to 'src/3rdparty/harfbuzz-ng/src/hb-cache.hh')
| -rw-r--r-- | src/3rdparty/harfbuzz-ng/src/hb-cache.hh | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/src/3rdparty/harfbuzz-ng/src/hb-cache.hh b/src/3rdparty/harfbuzz-ng/src/hb-cache.hh index 2e98187b50..6d8a54cf10 100644 --- a/src/3rdparty/harfbuzz-ng/src/hb-cache.hh +++ b/src/3rdparty/harfbuzz-ng/src/hb-cache.hh @@ -30,7 +30,19 @@ #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=16, unsigned int value_bits=8 + 32 - key_bits, @@ -50,14 +62,12 @@ struct hb_cache_t static_assert ((key_bits >= cache_bits), ""); static_assert ((key_bits + value_bits <= cache_bits + 8 * sizeof (item_t)), ""); - hb_cache_t () { init (); } - - void init () { clear (); } + hb_cache_t () { clear (); } void clear () { - for (unsigned i = 0; i < ARRAY_LENGTH (values); i++) - values[i] = -1; + for (auto &v : values) + v = -1; } bool get (unsigned int key, unsigned int *value) const |