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When matching second glyph of kerning pairs, use bsearch 

Roboto has glyphs (like 'F') that have 200 kerning pairs.
Add a handcoded bsearch instead of previous linear search.

This doesn't show much speedup though, apparently we spend the
bulk of the time somewhere before here.
This commit is contained in:
Behdad Esfahbod 2015-01-19 17:00:31 -08:00
parent e9f5c65be0
commit 67dfa8c7c2
1 changed files with 16 additions and 5 deletions
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21
src/hb-ot-layout-gpos-table.hh
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@ -602,12 +602,24 @@ struct PairSet
unsigned int len2 = valueFormats[1].get_len ();
unsigned int record_size = USHORT::static_size * (1 + len1 + len2);
const PairValueRecord *record = CastP<PairValueRecord> (arrayZ);
const PairValueRecord *record_array = CastP<PairValueRecord> (arrayZ);
unsigned int count = len;
for (unsigned int i = 0; i < count; i++)
/* Hand-coded bsearch. */
if (unlikely (!count))
return TRACE_RETURN (false);
hb_codepoint_t x = buffer->info[pos].codepoint;
int min = 0, max = (int) count - 1;
while (min <= max)
{
/* TODO bsearch */
if (buffer->info[pos].codepoint == record->secondGlyph)
int mid = (min + max) / 2;
const PairValueRecord *record = &StructAtOffset<PairValueRecord> (record_array, record_size * mid);
hb_codepoint_t mid_x = record->secondGlyph;
if (x < mid_x)
max = mid - 1;
else if (x > mid_x)
min = mid + 1;
else
{
valueFormats[0].apply_value (c->font, c->direction, this,
&record->values[0], buffer->cur_pos());
@ -618,7 +630,6 @@ struct PairSet
buffer->idx = pos;
return TRACE_RETURN (true);
}
record = &StructAtOffset<PairValueRecord> (record, record_size);
}
return TRACE_RETURN (false);