From 993c51915f503f74ee00eee646b67bf2e3f73596 Mon Sep 17 00:00:00 2001 From: Behdad Esfahbod Date: Sat, 9 Jun 2012 02:48:16 -0400 Subject: [PATCH] Add fast-path to GSUB to check coverage Shaves a good 10% off DejaVu Sans with simple Latin text for me. Now, DejaVu is very ChainContext-intensive, but it's also a very popular font! --- src/hb-ot-layout-gsub-table.hh | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/src/hb-ot-layout-gsub-table.hh b/src/hb-ot-layout-gsub-table.hh index 6a4199d..caaaa85 100644 --- a/src/hb-ot-layout-gsub-table.hh +++ b/src/hb-ot-layout-gsub-table.hh @@ -968,6 +968,17 @@ struct SubstLookupSubTable inline bool apply (hb_apply_context_t *c, unsigned int lookup_type) const { TRACE_APPLY (); + if (likely (lookup_type < Context) || + (hb_in_range (lookup_type, Context, ChainContext) && + hb_in_range (u.header.sub_format, 1, 2))) + { + /* Fast path, for most that have coverage in the same place. + * Note that ReverseChainSingle can also go through this but + * it's not worth the effort. */ + hb_codepoint_t glyph_id = c->buffer->cur().codepoint; + unsigned int index = (this+u.header.coverage) (glyph_id); + if (likely (index == NOT_COVERED)) return TRACE_RETURN (false); + } switch (lookup_type) { case Single: return TRACE_RETURN (u.single.apply (c)); case Multiple: return TRACE_RETURN (u.multiple.apply (c)); @@ -998,7 +1009,10 @@ struct SubstLookupSubTable private: union { - USHORT sub_format; + struct { + USHORT sub_format; + OffsetTo coverage; + } header; SingleSubst single; MultipleSubst multiple; AlternateSubst alternate; @@ -1009,7 +1023,7 @@ struct SubstLookupSubTable ReverseChainSingleSubst reverseChainContextSingle; } u; public: - DEFINE_SIZE_UNION (2, sub_format); + DEFINE_SIZE_UNION (2, header.sub_format); }; -- 2.7.4