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Speedup Device table delta computation for common cases

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This commit is contained in:
Behdad Esfahbod 2010-09-22 16:46:18 -04:00
parent ed4acbde9c
commit 5bd1e95236
1 changed files with 21 additions and 4 deletions
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25
src/hb-ot-layout-common-private.hh
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@ -1,5 +1,6 @@
/*
* Copyright (C) 2007,2008,2009 Red Hat, Inc.
* Copyright (C) 2010 Google, Inc.
*
* This is part of HarfBuzz, a text shaping library.
*
@ -22,6 +23,7 @@
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Red Hat Author(s): Behdad Esfahbod
* Google Author(s): Behdad Esfahbod
*/
#ifndef HB_OT_LAYOUT_COMMON_PRIVATE_HH
@ -519,15 +521,30 @@ struct ClassDef
struct Device
{
/* XXX speed up */
inline hb_position_t get_x_delta (hb_ot_layout_context_t *c) const
{ return c->font->x_ppem ? get_delta (c->font->x_ppem) * (uint64_t) c->font->x_scale / c->font->x_ppem : 0; }
{ return get_delta (c->font->x_ppem, c->font->x_scale); }
inline hb_position_t get_y_delta (hb_ot_layout_context_t *c) const
{ return c->font->y_ppem ? get_delta (c->font->y_ppem) * (uint64_t) c->font->y_scale / c->font->y_ppem : 0; }
{ return get_delta (c->font->y_ppem, c->font->y_scale); }
inline int get_delta (unsigned int ppem_size) const
inline int get_delta (unsigned int ppem, unsigned int scale) const
{
if (!ppem) return 0;
int pixels = get_delta_pixels (ppem);
if (!pixels) return 0;
/* pixels is at most in the -8..7 range. So 64-bit arithmetic is
* not really necessary here. A simple cast to int may just work
* as well. But since this code is not reached that often and
* for the sake of correctness, we do a 64bit operation. */
return pixels * (int64_t) scale / ppem;
}
inline int get_delta_pixels (unsigned int ppem_size) const
{
unsigned int f = deltaFormat;
if (unlikely (f < 1 || f > 3))