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Speed up redisplay of binary files with long series of nulls

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* src/bidi.c (bidi_resolve_weak): Avoid entering a loop searching
for a character needed for resolving the type of a series of BN
and ET characters, as required by rule W5 of UAX#9, if the results
of the resolution are known in advance, because we are at level
zero, and the previous strong character was L.
(bidi_resolve_neutral): Partially resurrect the optimization for a
long series of control characters in an otherwise strictly L2R
text.
(bidi_level_of_next_char): Don't enter the loop that searches for
a paragraph separator if the current character is already at base
embedding level.  (Bug#22739)
This commit is contained in:
Eli Zaretskii 2016-03-06 18:14:46 +02:00
parent e51b27ec2c
commit cc057e4313
1 changed files with 34 additions and 6 deletions
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36
src/bidi.c
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@ -2318,6 +2318,30 @@ bidi_resolve_weak (struct bidi_it *bidi_it)
if (bidi_it->next_en_type == WEAK_EN) /* ET/BN with EN after it */ if (bidi_it->next_en_type == WEAK_EN) /* ET/BN with EN after it */
type = WEAK_EN; type = WEAK_EN;
} }
else if (type == WEAK_BN
/* This condition is for the following important case:
. we are at level zero
. either previous strong character was L,
or we've seen no strong characters since sos
and the base paragraph direction is L2R
. this BN is NOT a bidi directional control
For such a situation, either this BN will be
converted to EN per W5, and then to L by virtue
of W7; or it will become ON per W6, and then L
because of N1/N2. So we take a shortcut here
and make it L right away, to avoid the
potentially costly loop below. This is
important when the buffer has a long series of
control characters, like binary nulls, and no
R2L characters at all. */
&& new_level == 0
&& !bidi_explicit_dir_char (bidi_it->ch)
&& ((bidi_it->last_strong.type == STRONG_L)
|| (bidi_it->last_strong.type == UNKNOWN_BT
&& bidi_it->sos == L2R)))
type = STRONG_L;
else if (bidi_it->next_en_pos >= 0) else if (bidi_it->next_en_pos >= 0)
{ {
/* We overstepped the last known position for ET /* We overstepped the last known position for ET
@ -2981,9 +3005,10 @@ bidi_resolve_neutral (struct bidi_it *bidi_it)
entering the expensive loop in the "else" clause. */ entering the expensive loop in the "else" clause. */
else if (current_level == 0 else if (current_level == 0
&& bidi_it->prev_for_neutral.type == STRONG_L && bidi_it->prev_for_neutral.type == STRONG_L
&& type != WEAK_BN && (ASCII_CHAR_P (bidi_it->ch)
|| (type != WEAK_BN
&& !bidi_explicit_dir_char (bidi_it->ch) && !bidi_explicit_dir_char (bidi_it->ch)
&& !bidi_isolate_fmt_char (type)) && !bidi_isolate_fmt_char (type))))
type = bidi_resolve_neutral_1 (bidi_it->prev_for_neutral.type, type = bidi_resolve_neutral_1 (bidi_it->prev_for_neutral.type,
STRONG_L, current_level); STRONG_L, current_level);
else if (/* current level is 1 */ else if (/* current level is 1 */
@ -3163,7 +3188,7 @@ bidi_level_of_next_char (struct bidi_it *bidi_it)
} }
} }
/* Perhaps the character we want is already cached s fully resolved. /* Perhaps the character we want is already cached as fully resolved.
If it is, the call to bidi_cache_find below will return a type If it is, the call to bidi_cache_find below will return a type
other than UNKNOWN_BT. */ other than UNKNOWN_BT. */
if (bidi_cache_idx > bidi_cache_start && !bidi_it->first_elt) if (bidi_cache_idx > bidi_cache_start && !bidi_it->first_elt)
@ -3223,7 +3248,10 @@ bidi_level_of_next_char (struct bidi_it *bidi_it)
if ((bidi_it->orig_type == NEUTRAL_WS if ((bidi_it->orig_type == NEUTRAL_WS
|| bidi_it->orig_type == WEAK_BN || bidi_it->orig_type == WEAK_BN
|| bidi_isolate_fmt_char (bidi_it->orig_type)) || bidi_isolate_fmt_char (bidi_it->orig_type))
&& bidi_it->next_for_ws.charpos < bidi_it->charpos) && bidi_it->next_for_ws.charpos < bidi_it->charpos
/* If this character is already at base level, we don't need to
reset it, so avoid the potentially costly loop below. */
&& level != bidi_it->level_stack[0].level)
{ {
int ch; int ch;
ptrdiff_t clen = bidi_it->ch_len; ptrdiff_t clen = bidi_it->ch_len;