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      1 /*
      2  * Copyright  2011,2012  Google, Inc.
      3  *
      4  *  This is part of HarfBuzz, a text shaping library.
      5  *
      6  * Permission is hereby granted, without written agreement and without
      7  * license or royalty fees, to use, copy, modify, and distribute this
      8  * software and its documentation for any purpose, provided that the
      9  * above copyright notice and the following two paragraphs appear in
     10  * all copies of this software.
     11  *
     12  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
     13  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
     14  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
     15  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
     16  * DAMAGE.
     17  *
     18  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
     19  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
     20  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
     21  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
     22  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
     23  *
     24  * Google Author(s): Behdad Esfahbod
     25  */
     26 
     27 #include "hb-ot-shape-complex-indic-private.hh"
     28 #include "hb-ot-layout-private.hh"
     29 
     30 /* buffer var allocations */
     31 #define indic_category() complex_var_u8_0() /* indic_category_t */
     32 #define indic_position() complex_var_u8_1() /* indic_position_t */
     33 
     34 
     35 /*
     36  * Indic shaper.
     37  */
     38 
     39 
     40 #define IN_HALF_BLOCK(u, Base) (((u) & ~0x7Fu) == (Base))
     41 
     42 #define IS_DEVA(u) (IN_HALF_BLOCK (u, 0x0900u))
     43 #define IS_BENG(u) (IN_HALF_BLOCK (u, 0x0980u))
     44 #define IS_GURU(u) (IN_HALF_BLOCK (u, 0x0A00u))
     45 #define IS_GUJR(u) (IN_HALF_BLOCK (u, 0x0A80u))
     46 #define IS_ORYA(u) (IN_HALF_BLOCK (u, 0x0B00u))
     47 #define IS_TAML(u) (IN_HALF_BLOCK (u, 0x0B80u))
     48 #define IS_TELU(u) (IN_HALF_BLOCK (u, 0x0C00u))
     49 #define IS_KNDA(u) (IN_HALF_BLOCK (u, 0x0C80u))
     50 #define IS_MLYM(u) (IN_HALF_BLOCK (u, 0x0D00u))
     51 #define IS_SINH(u) (IN_HALF_BLOCK (u, 0x0D80u))
     52 #define IS_KHMR(u) (IN_HALF_BLOCK (u, 0x1780u))
     53 
     54 
     55 #define MATRA_POS_LEFT(u)	POS_PRE_M
     56 #define MATRA_POS_RIGHT(u)	( \
     57 				  IS_DEVA(u) ? POS_AFTER_SUB  : \
     58 				  IS_BENG(u) ? POS_AFTER_POST : \
     59 				  IS_GURU(u) ? POS_AFTER_POST : \
     60 				  IS_GUJR(u) ? POS_AFTER_POST : \
     61 				  IS_ORYA(u) ? POS_AFTER_POST : \
     62 				  IS_TAML(u) ? POS_AFTER_POST : \
     63 				  IS_TELU(u) ? (u <= 0x0C42u ? POS_BEFORE_SUB : POS_AFTER_SUB) : \
     64 				  IS_KNDA(u) ? (u < 0x0CC3u || u > 0xCD6u ? POS_BEFORE_SUB : POS_AFTER_SUB) : \
     65 				  IS_MLYM(u) ? POS_AFTER_POST : \
     66 				  IS_SINH(u) ? POS_AFTER_SUB  : \
     67 				  IS_KHMR(u) ? POS_AFTER_POST : \
     68 				  /*default*/  POS_AFTER_SUB    \
     69 				)
     70 #define MATRA_POS_TOP(u)	( /* BENG and MLYM don't have top matras. */ \
     71 				  IS_DEVA(u) ? POS_AFTER_SUB  : \
     72 				  IS_GURU(u) ? POS_AFTER_POST : /* Deviate from spec */ \
     73 				  IS_GUJR(u) ? POS_AFTER_SUB  : \
     74 				  IS_ORYA(u) ? POS_AFTER_MAIN : \
     75 				  IS_TAML(u) ? POS_AFTER_SUB  : \
     76 				  IS_TELU(u) ? POS_BEFORE_SUB : \
     77 				  IS_KNDA(u) ? POS_BEFORE_SUB : \
     78 				  IS_SINH(u) ? POS_AFTER_SUB  : \
     79 				  IS_KHMR(u) ? POS_AFTER_POST : \
     80 				  /*default*/  POS_AFTER_SUB    \
     81 				)
     82 #define MATRA_POS_BOTTOM(u)	( \
     83 				  IS_DEVA(u) ? POS_AFTER_SUB  : \
     84 				  IS_BENG(u) ? POS_AFTER_SUB  : \
     85 				  IS_GURU(u) ? POS_AFTER_POST : \
     86 				  IS_GUJR(u) ? POS_AFTER_POST : \
     87 				  IS_ORYA(u) ? POS_AFTER_SUB  : \
     88 				  IS_TAML(u) ? POS_AFTER_POST : \
     89 				  IS_TELU(u) ? POS_BEFORE_SUB : \
     90 				  IS_KNDA(u) ? POS_BEFORE_SUB : \
     91 				  IS_MLYM(u) ? POS_AFTER_POST : \
     92 				  IS_SINH(u) ? POS_AFTER_SUB  : \
     93 				  IS_KHMR(u) ? POS_AFTER_POST : \
     94 				  /*default*/  POS_AFTER_SUB    \
     95 				)
     96 
     97 static inline indic_position_t
     98 matra_position (hb_codepoint_t u, indic_position_t side)
     99 {
    100   switch ((int) side)
    101   {
    102     case POS_PRE_C:	return MATRA_POS_LEFT (u);
    103     case POS_POST_C:	return MATRA_POS_RIGHT (u);
    104     case POS_ABOVE_C:	return MATRA_POS_TOP (u);
    105     case POS_BELOW_C:	return MATRA_POS_BOTTOM (u);
    106   };
    107   return side;
    108 }
    109 
    110 /* XXX
    111  * This is a hack for now.  We should move this data into the main Indic table.
    112  * Or completely remove it and just check in the tables.
    113  */
    114 static const hb_codepoint_t ra_chars[] = {
    115   0x0930u, /* Devanagari */
    116   0x09B0u, /* Bengali */
    117   0x09F0u, /* Bengali */
    118   0x0A30u, /* Gurmukhi */	/* No Reph */
    119   0x0AB0u, /* Gujarati */
    120   0x0B30u, /* Oriya */
    121   0x0BB0u, /* Tamil */		/* No Reph */
    122   0x0C30u, /* Telugu */		/* Reph formed only with ZWJ */
    123   0x0CB0u, /* Kannada */
    124   0x0D30u, /* Malayalam */	/* No Reph, Logical Repha */
    125 
    126   0x0DBBu, /* Sinhala */		/* Reph formed only with ZWJ */
    127 
    128   0x179Au, /* Khmer */		/* No Reph, Visual Repha */
    129 };
    130 
    131 static inline bool
    132 is_ra (hb_codepoint_t u)
    133 {
    134   for (unsigned int i = 0; i < ARRAY_LENGTH (ra_chars); i++)
    135     if (u == ra_chars[i])
    136       return true;
    137   return false;
    138 }
    139 
    140 static inline bool
    141 is_one_of (const hb_glyph_info_t &info, unsigned int flags)
    142 {
    143   /* If it ligated, all bets are off. */
    144   if (_hb_glyph_info_ligated (&info)) return false;
    145   return !!(FLAG_SAFE (info.indic_category()) & flags);
    146 }
    147 
    148 static inline bool
    149 is_joiner (const hb_glyph_info_t &info)
    150 {
    151   return is_one_of (info, JOINER_FLAGS);
    152 }
    153 
    154 static inline bool
    155 is_consonant (const hb_glyph_info_t &info)
    156 {
    157   return is_one_of (info, CONSONANT_FLAGS);
    158 }
    159 
    160 static inline bool
    161 is_halant_or_coeng (const hb_glyph_info_t &info)
    162 {
    163   return is_one_of (info, HALANT_OR_COENG_FLAGS);
    164 }
    165 
    166 static inline void
    167 set_indic_properties (hb_glyph_info_t &info)
    168 {
    169   hb_codepoint_t u = info.codepoint;
    170   unsigned int type = hb_indic_get_categories (u);
    171   indic_category_t cat = (indic_category_t) (type & 0x7Fu);
    172   indic_position_t pos = (indic_position_t) (type >> 8);
    173 
    174 
    175   /*
    176    * Re-assign category
    177    */
    178 
    179   /* The following act more like the Bindus. */
    180   if (unlikely (hb_in_range (u, 0x0953u, 0x0954u)))
    181     cat = OT_SM;
    182   /* The following act like consonants. */
    183   else if (unlikely (hb_in_ranges (u, 0x0A72u, 0x0A73u,
    184 				      0x1CF5u, 0x1CF6u)))
    185     cat = OT_C;
    186   /* TODO: The following should only be allowed after a Visarga.
    187    * For now, just treat them like regular tone marks. */
    188   else if (unlikely (hb_in_range (u, 0x1CE2u, 0x1CE8u)))
    189     cat = OT_A;
    190   /* TODO: The following should only be allowed after some of
    191    * the nasalization marks, maybe only for U+1CE9..U+1CF1.
    192    * For now, just treat them like tone marks. */
    193   else if (unlikely (u == 0x1CEDu))
    194     cat = OT_A;
    195   /* The following take marks in standalone clusters, similar to Avagraha. */
    196   else if (unlikely (hb_in_ranges (u, 0xA8F2u, 0xA8F7u,
    197 				      0x1CE9u, 0x1CECu,
    198 				      0x1CEEu, 0x1CF1u)))
    199   {
    200     cat = OT_Symbol;
    201     ASSERT_STATIC ((int) INDIC_SYLLABIC_CATEGORY_AVAGRAHA == OT_Symbol);
    202   }
    203   else if (unlikely (u == 0x17C6u)) cat = OT_N; /* Khmer Bindu doesn't like to be repositioned. */
    204   else if (unlikely (hb_in_range (u, 0x2010u, 0x2011u)))
    205 				    cat = OT_PLACEHOLDER;
    206   else if (unlikely (u == 0x25CCu)) cat = OT_DOTTEDCIRCLE;
    207 
    208 
    209   /*
    210    * Re-assign position.
    211    */
    212 
    213   if ((FLAG_SAFE (cat) & CONSONANT_FLAGS))
    214   {
    215     pos = POS_BASE_C;
    216     if (is_ra (u))
    217       cat = OT_Ra;
    218   }
    219   else if (cat == OT_M)
    220   {
    221     pos = matra_position (u, pos);
    222   }
    223   else if ((FLAG_SAFE (cat) & (FLAG (OT_SM) | FLAG (OT_VD) | FLAG (OT_A) | FLAG (OT_Symbol))))
    224   {
    225     pos = POS_SMVD;
    226   }
    227 
    228   if (unlikely (u == 0x0B01u)) pos = POS_BEFORE_SUB; /* Oriya Bindu is BeforeSub in the spec. */
    229 
    230 
    231 
    232   info.indic_category() = cat;
    233   info.indic_position() = pos;
    234 }
    235 
    236 /*
    237  * Things above this line should ideally be moved to the Indic table itself.
    238  */
    239 
    240 
    241 /*
    242  * Indic configurations.  Note that we do not want to keep every single script-specific
    243  * behavior in these tables necessarily.  This should mainly be used for per-script
    244  * properties that are cheaper keeping here, than in the code.  Ie. if, say, one and
    245  * only one script has an exception, that one script can be if'ed directly in the code,
    246  * instead of adding a new flag in these structs.
    247  */
    248 
    249 enum base_position_t {
    250   BASE_POS_FIRST,
    251   BASE_POS_LAST_SINHALA,
    252   BASE_POS_LAST
    253 };
    254 enum reph_position_t {
    255   REPH_POS_AFTER_MAIN  = POS_AFTER_MAIN,
    256   REPH_POS_BEFORE_SUB  = POS_BEFORE_SUB,
    257   REPH_POS_AFTER_SUB   = POS_AFTER_SUB,
    258   REPH_POS_BEFORE_POST = POS_BEFORE_POST,
    259   REPH_POS_AFTER_POST  = POS_AFTER_POST,
    260   REPH_POS_DONT_CARE   = POS_RA_TO_BECOME_REPH
    261 };
    262 enum reph_mode_t {
    263   REPH_MODE_IMPLICIT,  /* Reph formed out of initial Ra,H sequence. */
    264   REPH_MODE_EXPLICIT,  /* Reph formed out of initial Ra,H,ZWJ sequence. */
    265   REPH_MODE_VIS_REPHA, /* Encoded Repha character, no reordering needed. */
    266   REPH_MODE_LOG_REPHA  /* Encoded Repha character, needs reordering. */
    267 };
    268 enum blwf_mode_t {
    269   BLWF_MODE_PRE_AND_POST, /* Below-forms feature applied to pre-base and post-base. */
    270   BLWF_MODE_POST_ONLY     /* Below-forms feature applied to post-base only. */
    271 };
    272 struct indic_config_t
    273 {
    274   hb_script_t     script;
    275   bool            has_old_spec;
    276   hb_codepoint_t  virama;
    277   base_position_t base_pos;
    278   reph_position_t reph_pos;
    279   reph_mode_t     reph_mode;
    280   blwf_mode_t     blwf_mode;
    281 };
    282 
    283 static const indic_config_t indic_configs[] =
    284 {
    285   /* Default.  Should be first. */
    286   {HB_SCRIPT_INVALID,	false,      0,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
    287   {HB_SCRIPT_DEVANAGARI,true, 0x094Du,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
    288   {HB_SCRIPT_BENGALI,	true, 0x09CDu,BASE_POS_LAST, REPH_POS_AFTER_SUB,  REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
    289   {HB_SCRIPT_GURMUKHI,	true, 0x0A4Du,BASE_POS_LAST, REPH_POS_BEFORE_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
    290   {HB_SCRIPT_GUJARATI,	true, 0x0ACDu,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
    291   {HB_SCRIPT_ORIYA,	true, 0x0B4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
    292   {HB_SCRIPT_TAMIL,	true, 0x0BCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
    293   {HB_SCRIPT_TELUGU,	true, 0x0C4Du,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_POST_ONLY},
    294   {HB_SCRIPT_KANNADA,	true, 0x0CCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_POST_ONLY},
    295   {HB_SCRIPT_MALAYALAM,	true, 0x0D4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_LOG_REPHA,BLWF_MODE_PRE_AND_POST},
    296   {HB_SCRIPT_SINHALA,	false,0x0DCAu,BASE_POS_LAST_SINHALA,
    297 						     REPH_POS_AFTER_MAIN, REPH_MODE_EXPLICIT, BLWF_MODE_PRE_AND_POST},
    298   {HB_SCRIPT_KHMER,	false,0x17D2u,BASE_POS_FIRST,REPH_POS_DONT_CARE,  REPH_MODE_VIS_REPHA,BLWF_MODE_PRE_AND_POST},
    299 };
    300 
    301 
    302 
    303 /*
    304  * Indic shaper.
    305  */
    306 
    307 struct feature_list_t {
    308   hb_tag_t tag;
    309   hb_ot_map_feature_flags_t flags;
    310 };
    311 
    312 static const feature_list_t
    313 indic_features[] =
    314 {
    315   /*
    316    * Basic features.
    317    * These features are applied in order, one at a time, after initial_reordering.
    318    */
    319   {HB_TAG('n','u','k','t'), F_GLOBAL},
    320   {HB_TAG('a','k','h','n'), F_GLOBAL},
    321   {HB_TAG('r','p','h','f'), F_NONE},
    322   {HB_TAG('r','k','r','f'), F_GLOBAL},
    323   {HB_TAG('p','r','e','f'), F_NONE},
    324   {HB_TAG('b','l','w','f'), F_NONE},
    325   {HB_TAG('a','b','v','f'), F_NONE},
    326   {HB_TAG('h','a','l','f'), F_NONE},
    327   {HB_TAG('p','s','t','f'), F_NONE},
    328   {HB_TAG('v','a','t','u'), F_GLOBAL},
    329   {HB_TAG('c','j','c','t'), F_GLOBAL},
    330   {HB_TAG('c','f','a','r'), F_NONE},
    331   /*
    332    * Other features.
    333    * These features are applied all at once, after final_reordering.
    334    * Default Bengali font in Windows for example has intermixed
    335    * lookups for init,pres,abvs,blws features.
    336    */
    337   {HB_TAG('i','n','i','t'), F_NONE},
    338   {HB_TAG('p','r','e','s'), F_GLOBAL},
    339   {HB_TAG('a','b','v','s'), F_GLOBAL},
    340   {HB_TAG('b','l','w','s'), F_GLOBAL},
    341   {HB_TAG('p','s','t','s'), F_GLOBAL},
    342   {HB_TAG('h','a','l','n'), F_GLOBAL},
    343   /* Positioning features, though we don't care about the types. */
    344   {HB_TAG('d','i','s','t'), F_GLOBAL},
    345   {HB_TAG('a','b','v','m'), F_GLOBAL},
    346   {HB_TAG('b','l','w','m'), F_GLOBAL},
    347 };
    348 
    349 /*
    350  * Must be in the same order as the indic_features array.
    351  */
    352 enum {
    353   _NUKT,
    354   _AKHN,
    355   RPHF,
    356   _RKRF,
    357   PREF,
    358   BLWF,
    359   ABVF,
    360   HALF,
    361   PSTF,
    362   _VATU,
    363   _CJCT,
    364   CFAR,
    365 
    366   INIT,
    367   _PRES,
    368   _ABVS,
    369   _BLWS,
    370   _PSTS,
    371   _HALN,
    372   _DIST,
    373   _ABVM,
    374   _BLWM,
    375 
    376   INDIC_NUM_FEATURES,
    377   INDIC_BASIC_FEATURES = INIT /* Don't forget to update this! */
    378 };
    379 
    380 static void
    381 setup_syllables (const hb_ot_shape_plan_t *plan,
    382 		 hb_font_t *font,
    383 		 hb_buffer_t *buffer);
    384 static void
    385 initial_reordering (const hb_ot_shape_plan_t *plan,
    386 		    hb_font_t *font,
    387 		    hb_buffer_t *buffer);
    388 static void
    389 final_reordering (const hb_ot_shape_plan_t *plan,
    390 		  hb_font_t *font,
    391 		  hb_buffer_t *buffer);
    392 static void
    393 clear_syllables (const hb_ot_shape_plan_t *plan,
    394 		 hb_font_t *font,
    395 		 hb_buffer_t *buffer);
    396 
    397 static void
    398 collect_features_indic (hb_ot_shape_planner_t *plan)
    399 {
    400   hb_ot_map_builder_t *map = &plan->map;
    401 
    402   /* Do this before any lookups have been applied. */
    403   map->add_gsub_pause (setup_syllables);
    404 
    405   map->add_global_bool_feature (HB_TAG('l','o','c','l'));
    406   /* The Indic specs do not require ccmp, but we apply it here since if
    407    * there is a use of it, it's typically at the beginning. */
    408   map->add_global_bool_feature (HB_TAG('c','c','m','p'));
    409 
    410 
    411   unsigned int i = 0;
    412   map->add_gsub_pause (initial_reordering);
    413   for (; i < INDIC_BASIC_FEATURES; i++) {
    414     map->add_feature (indic_features[i].tag, 1, indic_features[i].flags | F_MANUAL_ZWJ);
    415     map->add_gsub_pause (NULL);
    416   }
    417   map->add_gsub_pause (final_reordering);
    418   for (; i < INDIC_NUM_FEATURES; i++) {
    419     map->add_feature (indic_features[i].tag, 1, indic_features[i].flags | F_MANUAL_ZWJ);
    420   }
    421 
    422   map->add_global_bool_feature (HB_TAG('c','a','l','t'));
    423   map->add_global_bool_feature (HB_TAG('c','l','i','g'));
    424 
    425   map->add_gsub_pause (clear_syllables);
    426 }
    427 
    428 static void
    429 override_features_indic (hb_ot_shape_planner_t *plan)
    430 {
    431   /* Uniscribe does not apply 'kern' in Khmer. */
    432   if (hb_options ().uniscribe_bug_compatible)
    433   {
    434     switch ((hb_tag_t) plan->props.script)
    435     {
    436       case HB_SCRIPT_KHMER:
    437 	plan->map.add_feature (HB_TAG('k','e','r','n'), 0, F_GLOBAL);
    438 	break;
    439     }
    440   }
    441 
    442   plan->map.add_feature (HB_TAG('l','i','g','a'), 0, F_GLOBAL);
    443 }
    444 
    445 
    446 struct would_substitute_feature_t
    447 {
    448   inline void init (const hb_ot_map_t *map, hb_tag_t feature_tag, bool zero_context_)
    449   {
    450     zero_context = zero_context_;
    451     map->get_stage_lookups (0/*GSUB*/,
    452 			    map->get_feature_stage (0/*GSUB*/, feature_tag),
    453 			    &lookups, &count);
    454   }
    455 
    456   inline bool would_substitute (const hb_codepoint_t *glyphs,
    457 				unsigned int          glyphs_count,
    458 				hb_face_t            *face) const
    459   {
    460     for (unsigned int i = 0; i < count; i++)
    461       if (hb_ot_layout_lookup_would_substitute_fast (face, lookups[i].index, glyphs, glyphs_count, zero_context))
    462 	return true;
    463     return false;
    464   }
    465 
    466   private:
    467   const hb_ot_map_t::lookup_map_t *lookups;
    468   unsigned int count;
    469   bool zero_context;
    470 };
    471 
    472 struct indic_shape_plan_t
    473 {
    474   ASSERT_POD ();
    475 
    476   inline bool get_virama_glyph (hb_font_t *font, hb_codepoint_t *pglyph) const
    477   {
    478     hb_codepoint_t glyph = virama_glyph;
    479     if (unlikely (virama_glyph == (hb_codepoint_t) -1))
    480     {
    481       if (!config->virama || !font->get_nominal_glyph (config->virama, &glyph))
    482 	glyph = 0;
    483       /* Technically speaking, the spec says we should apply 'locl' to virama too.
    484        * Maybe one day... */
    485 
    486       /* Our get_nominal_glyph() function needs a font, so we can't get the virama glyph
    487        * during shape planning...  Instead, overwrite it here.  It's safe.  Don't worry! */
    488       (const_cast<indic_shape_plan_t *> (this))->virama_glyph = glyph;
    489     }
    490 
    491     *pglyph = glyph;
    492     return glyph != 0;
    493   }
    494 
    495   const indic_config_t *config;
    496 
    497   bool is_old_spec;
    498   hb_codepoint_t virama_glyph;
    499 
    500   would_substitute_feature_t rphf;
    501   would_substitute_feature_t pref;
    502   would_substitute_feature_t blwf;
    503   would_substitute_feature_t pstf;
    504 
    505   hb_mask_t mask_array[INDIC_NUM_FEATURES];
    506 };
    507 
    508 static void *
    509 data_create_indic (const hb_ot_shape_plan_t *plan)
    510 {
    511   indic_shape_plan_t *indic_plan = (indic_shape_plan_t *) calloc (1, sizeof (indic_shape_plan_t));
    512   if (unlikely (!indic_plan))
    513     return NULL;
    514 
    515   indic_plan->config = &indic_configs[0];
    516   for (unsigned int i = 1; i < ARRAY_LENGTH (indic_configs); i++)
    517     if (plan->props.script == indic_configs[i].script) {
    518       indic_plan->config = &indic_configs[i];
    519       break;
    520     }
    521 
    522   indic_plan->is_old_spec = indic_plan->config->has_old_spec && ((plan->map.chosen_script[0] & 0x000000FFu) != '2');
    523   indic_plan->virama_glyph = (hb_codepoint_t) -1;
    524 
    525   /* Use zero-context would_substitute() matching for new-spec of the main
    526    * Indic scripts, and scripts with one spec only, but not for old-specs.
    527    * The new-spec for all dual-spec scripts says zero-context matching happens.
    528    *
    529    * However, testing with Malayalam shows that old and new spec both allow
    530    * context.  Testing with Bengali new-spec however shows that it doesn't.
    531    * So, the heuristic here is the way it is.  It should *only* be changed,
    532    * as we discover more cases of what Windows does.  DON'T TOUCH OTHERWISE.
    533    */
    534   bool zero_context = !indic_plan->is_old_spec && plan->props.script != HB_SCRIPT_MALAYALAM;
    535   indic_plan->rphf.init (&plan->map, HB_TAG('r','p','h','f'), zero_context);
    536   indic_plan->pref.init (&plan->map, HB_TAG('p','r','e','f'), zero_context);
    537   indic_plan->blwf.init (&plan->map, HB_TAG('b','l','w','f'), zero_context);
    538   indic_plan->pstf.init (&plan->map, HB_TAG('p','s','t','f'), zero_context);
    539 
    540   for (unsigned int i = 0; i < ARRAY_LENGTH (indic_plan->mask_array); i++)
    541     indic_plan->mask_array[i] = (indic_features[i].flags & F_GLOBAL) ?
    542 				 0 : plan->map.get_1_mask (indic_features[i].tag);
    543 
    544   return indic_plan;
    545 }
    546 
    547 static void
    548 data_destroy_indic (void *data)
    549 {
    550   free (data);
    551 }
    552 
    553 static indic_position_t
    554 consonant_position_from_face (const indic_shape_plan_t *indic_plan,
    555 			      const hb_codepoint_t consonant,
    556 			      const hb_codepoint_t virama,
    557 			      hb_face_t *face)
    558 {
    559   /* For old-spec, the order of glyphs is Consonant,Virama,
    560    * whereas for new-spec, it's Virama,Consonant.  However,
    561    * some broken fonts (like Free Sans) simply copied lookups
    562    * from old-spec to new-spec without modification.
    563    * And oddly enough, Uniscribe seems to respect those lookups.
    564    * Eg. in the sequence U+0924,U+094D,U+0930, Uniscribe finds
    565    * base at 0.  The font however, only has lookups matching
    566    * 930,94D in 'blwf', not the expected 94D,930 (with new-spec
    567    * table).  As such, we simply match both sequences.  Seems
    568    * to work. */
    569   hb_codepoint_t glyphs[3] = {virama, consonant, virama};
    570   if (indic_plan->blwf.would_substitute (glyphs  , 2, face) ||
    571       indic_plan->blwf.would_substitute (glyphs+1, 2, face))
    572     return POS_BELOW_C;
    573   if (indic_plan->pstf.would_substitute (glyphs  , 2, face) ||
    574       indic_plan->pstf.would_substitute (glyphs+1, 2, face))
    575     return POS_POST_C;
    576   if (indic_plan->pref.would_substitute (glyphs  , 2, face) ||
    577       indic_plan->pref.would_substitute (glyphs+1, 2, face))
    578     return POS_POST_C;
    579   return POS_BASE_C;
    580 }
    581 
    582 
    583 enum syllable_type_t {
    584   consonant_syllable,
    585   vowel_syllable,
    586   standalone_cluster,
    587   symbol_cluster,
    588   broken_cluster,
    589   non_indic_cluster,
    590 };
    591 
    592 #include "hb-ot-shape-complex-indic-machine.hh"
    593 
    594 
    595 static void
    596 setup_masks_indic (const hb_ot_shape_plan_t *plan HB_UNUSED,
    597 		   hb_buffer_t              *buffer,
    598 		   hb_font_t                *font HB_UNUSED)
    599 {
    600   HB_BUFFER_ALLOCATE_VAR (buffer, indic_category);
    601   HB_BUFFER_ALLOCATE_VAR (buffer, indic_position);
    602 
    603   /* We cannot setup masks here.  We save information about characters
    604    * and setup masks later on in a pause-callback. */
    605 
    606   unsigned int count = buffer->len;
    607   hb_glyph_info_t *info = buffer->info;
    608   for (unsigned int i = 0; i < count; i++)
    609     set_indic_properties (info[i]);
    610 }
    611 
    612 static void
    613 setup_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
    614 		 hb_font_t *font HB_UNUSED,
    615 		 hb_buffer_t *buffer)
    616 {
    617   find_syllables (buffer);
    618 }
    619 
    620 static int
    621 compare_indic_order (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb)
    622 {
    623   int a = pa->indic_position();
    624   int b = pb->indic_position();
    625 
    626   return a < b ? -1 : a == b ? 0 : +1;
    627 }
    628 
    629 
    630 
    631 static void
    632 update_consonant_positions (const hb_ot_shape_plan_t *plan,
    633 			    hb_font_t         *font,
    634 			    hb_buffer_t       *buffer)
    635 {
    636   const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
    637 
    638   if (indic_plan->config->base_pos != BASE_POS_LAST)
    639     return;
    640 
    641   hb_codepoint_t virama;
    642   if (indic_plan->get_virama_glyph (font, &virama))
    643   {
    644     hb_face_t *face = font->face;
    645     unsigned int count = buffer->len;
    646     hb_glyph_info_t *info = buffer->info;
    647     for (unsigned int i = 0; i < count; i++)
    648       if (info[i].indic_position() == POS_BASE_C)
    649       {
    650 	hb_codepoint_t consonant = info[i].codepoint;
    651 	info[i].indic_position() = consonant_position_from_face (indic_plan, consonant, virama, face);
    652       }
    653   }
    654 }
    655 
    656 
    657 /* Rules from:
    658  * https://www.microsoft.com/typography/otfntdev/devanot/shaping.aspx */
    659 
    660 static void
    661 initial_reordering_consonant_syllable (const hb_ot_shape_plan_t *plan,
    662 				       hb_face_t *face,
    663 				       hb_buffer_t *buffer,
    664 				       unsigned int start, unsigned int end)
    665 {
    666   const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
    667   hb_glyph_info_t *info = buffer->info;
    668 
    669 
    670   /* 1. Find base consonant:
    671    *
    672    * The shaping engine finds the base consonant of the syllable, using the
    673    * following algorithm: starting from the end of the syllable, move backwards
    674    * until a consonant is found that does not have a below-base or post-base
    675    * form (post-base forms have to follow below-base forms), or that is not a
    676    * pre-base reordering Ra, or arrive at the first consonant. The consonant
    677    * stopped at will be the base.
    678    *
    679    *   o If the syllable starts with Ra + Halant (in a script that has Reph)
    680    *     and has more than one consonant, Ra is excluded from candidates for
    681    *     base consonants.
    682    */
    683 
    684   unsigned int base = end;
    685   bool has_reph = false;
    686 
    687   {
    688     /* -> If the syllable starts with Ra + Halant (in a script that has Reph)
    689      *    and has more than one consonant, Ra is excluded from candidates for
    690      *    base consonants. */
    691     unsigned int limit = start;
    692     if (indic_plan->config->reph_pos != REPH_POS_DONT_CARE &&
    693 	indic_plan->mask_array[RPHF] &&
    694 	start + 3 <= end &&
    695 	(
    696 	 (indic_plan->config->reph_mode == REPH_MODE_IMPLICIT && !is_joiner (info[start + 2])) ||
    697 	 (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT && info[start + 2].indic_category() == OT_ZWJ)
    698 	))
    699     {
    700       /* See if it matches the 'rphf' feature. */
    701       hb_codepoint_t glyphs[3] = {info[start].codepoint,
    702 				  info[start + 1].codepoint,
    703 				  indic_plan->config->reph_mode == REPH_MODE_EXPLICIT ?
    704 				    info[start + 2].codepoint : 0};
    705       if (indic_plan->rphf.would_substitute (glyphs, 2, face) ||
    706 	  (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT &&
    707 	   indic_plan->rphf.would_substitute (glyphs, 3, face)))
    708       {
    709 	limit += 2;
    710 	while (limit < end && is_joiner (info[limit]))
    711 	  limit++;
    712 	base = start;
    713 	has_reph = true;
    714       }
    715     } else if (indic_plan->config->reph_mode == REPH_MODE_LOG_REPHA && info[start].indic_category() == OT_Repha)
    716     {
    717 	limit += 1;
    718 	while (limit < end && is_joiner (info[limit]))
    719 	  limit++;
    720 	base = start;
    721 	has_reph = true;
    722     }
    723 
    724     switch (indic_plan->config->base_pos)
    725     {
    726       case BASE_POS_LAST:
    727       {
    728 	/* -> starting from the end of the syllable, move backwards */
    729 	unsigned int i = end;
    730 	bool seen_below = false;
    731 	do {
    732 	  i--;
    733 	  /* -> until a consonant is found */
    734 	  if (is_consonant (info[i]))
    735 	  {
    736 	    /* -> that does not have a below-base or post-base form
    737 	     * (post-base forms have to follow below-base forms), */
    738 	    if (info[i].indic_position() != POS_BELOW_C &&
    739 		(info[i].indic_position() != POS_POST_C || seen_below))
    740 	    {
    741 	      base = i;
    742 	      break;
    743 	    }
    744 	    if (info[i].indic_position() == POS_BELOW_C)
    745 	      seen_below = true;
    746 
    747 	    /* -> or that is not a pre-base reordering Ra,
    748 	     *
    749 	     * IMPLEMENTATION NOTES:
    750 	     *
    751 	     * Our pre-base reordering Ra's are marked POS_POST_C, so will be skipped
    752 	     * by the logic above already.
    753 	     */
    754 
    755 	    /* -> or arrive at the first consonant. The consonant stopped at will
    756 	     * be the base. */
    757 	    base = i;
    758 	  }
    759 	  else
    760 	  {
    761 	    /* A ZWJ after a Halant stops the base search, and requests an explicit
    762 	     * half form.
    763 	     * A ZWJ before a Halant, requests a subjoined form instead, and hence
    764 	     * search continues.  This is particularly important for Bengali
    765 	     * sequence Ra,H,Ya that should form Ya-Phalaa by subjoining Ya. */
    766 	    if (start < i &&
    767 		info[i].indic_category() == OT_ZWJ &&
    768 		info[i - 1].indic_category() == OT_H)
    769 	      break;
    770 	  }
    771 	} while (i > limit);
    772       }
    773       break;
    774 
    775       case BASE_POS_LAST_SINHALA:
    776       {
    777         /* Sinhala base positioning is slightly different from main Indic, in that:
    778 	 * 1. Its ZWJ behavior is different,
    779 	 * 2. We don't need to look into the font for consonant positions.
    780 	 */
    781 
    782 	if (!has_reph)
    783 	  base = limit;
    784 
    785 	/* Find the last base consonant that is not blocked by ZWJ.  If there is
    786 	 * a ZWJ right before a base consonant, that would request a subjoined form. */
    787 	for (unsigned int i = limit; i < end; i++)
    788 	  if (is_consonant (info[i]))
    789 	  {
    790 	    if (limit < i && info[i - 1].indic_category() == OT_ZWJ)
    791 	      break;
    792 	    else
    793 	      base = i;
    794 	  }
    795 
    796 	/* Mark all subsequent consonants as below. */
    797 	for (unsigned int i = base + 1; i < end; i++)
    798 	  if (is_consonant (info[i]))
    799 	    info[i].indic_position() = POS_BELOW_C;
    800       }
    801       break;
    802 
    803       case BASE_POS_FIRST:
    804       {
    805 	/* The first consonant is always the base. */
    806 
    807 	assert (indic_plan->config->reph_mode == REPH_MODE_VIS_REPHA);
    808 	assert (!has_reph);
    809 
    810 	base = start;
    811 
    812 	/* Mark all subsequent consonants as below. */
    813 	for (unsigned int i = base + 1; i < end; i++)
    814 	  if (is_consonant (info[i]))
    815 	    info[i].indic_position() = POS_BELOW_C;
    816       }
    817       break;
    818     }
    819 
    820     /* -> If the syllable starts with Ra + Halant (in a script that has Reph)
    821      *    and has more than one consonant, Ra is excluded from candidates for
    822      *    base consonants.
    823      *
    824      *  Only do this for unforced Reph. (ie. not for Ra,H,ZWJ. */
    825     if (has_reph && base == start && limit - base <= 2) {
    826       /* Have no other consonant, so Reph is not formed and Ra becomes base. */
    827       has_reph = false;
    828     }
    829   }
    830 
    831 
    832   /* 2. Decompose and reorder Matras:
    833    *
    834    * Each matra and any syllable modifier sign in the cluster are moved to the
    835    * appropriate position relative to the consonant(s) in the cluster. The
    836    * shaping engine decomposes two- or three-part matras into their constituent
    837    * parts before any repositioning. Matra characters are classified by which
    838    * consonant in a conjunct they have affinity for and are reordered to the
    839    * following positions:
    840    *
    841    *   o Before first half form in the syllable
    842    *   o After subjoined consonants
    843    *   o After post-form consonant
    844    *   o After main consonant (for above marks)
    845    *
    846    * IMPLEMENTATION NOTES:
    847    *
    848    * The normalize() routine has already decomposed matras for us, so we don't
    849    * need to worry about that.
    850    */
    851 
    852 
    853   /* 3.  Reorder marks to canonical order:
    854    *
    855    * Adjacent nukta and halant or nukta and vedic sign are always repositioned
    856    * if necessary, so that the nukta is first.
    857    *
    858    * IMPLEMENTATION NOTES:
    859    *
    860    * We don't need to do this: the normalize() routine already did this for us.
    861    */
    862 
    863 
    864   /* Reorder characters */
    865 
    866   for (unsigned int i = start; i < base; i++)
    867     info[i].indic_position() = MIN (POS_PRE_C, (indic_position_t) info[i].indic_position());
    868 
    869   if (base < end)
    870     info[base].indic_position() = POS_BASE_C;
    871 
    872   /* Mark final consonants.  A final consonant is one appearing after a matra,
    873    * like in Khmer. */
    874   for (unsigned int i = base + 1; i < end; i++)
    875     if (info[i].indic_category() == OT_M) {
    876       for (unsigned int j = i + 1; j < end; j++)
    877         if (is_consonant (info[j])) {
    878 	  info[j].indic_position() = POS_FINAL_C;
    879 	  break;
    880 	}
    881       break;
    882     }
    883 
    884   /* Handle beginning Ra */
    885   if (has_reph)
    886     info[start].indic_position() = POS_RA_TO_BECOME_REPH;
    887 
    888   /* For old-style Indic script tags, move the first post-base Halant after
    889    * last consonant.
    890    *
    891    * Reports suggest that in some scripts Uniscribe does this only if there
    892    * is *not* a Halant after last consonant already (eg. Kannada), while it
    893    * does it unconditionally in other scripts (eg. Malayalam).  We don't
    894    * currently know about other scripts, so we single out Malayalam for now.
    895    *
    896    * Kannada test case:
    897    * U+0C9A,U+0CCD,U+0C9A,U+0CCD
    898    * With some versions of Lohit Kannada.
    899    * https://bugs.freedesktop.org/show_bug.cgi?id=59118
    900    *
    901    * Malayalam test case:
    902    * U+0D38,U+0D4D,U+0D31,U+0D4D,U+0D31,U+0D4D
    903    * With lohit-ttf-20121122/Lohit-Malayalam.ttf
    904    */
    905   if (indic_plan->is_old_spec)
    906   {
    907     bool disallow_double_halants = buffer->props.script != HB_SCRIPT_MALAYALAM;
    908     for (unsigned int i = base + 1; i < end; i++)
    909       if (info[i].indic_category() == OT_H)
    910       {
    911         unsigned int j;
    912         for (j = end - 1; j > i; j--)
    913 	  if (is_consonant (info[j]) ||
    914 	      (disallow_double_halants && info[j].indic_category() == OT_H))
    915 	    break;
    916 	if (info[j].indic_category() != OT_H && j > i) {
    917 	  /* Move Halant to after last consonant. */
    918 	  hb_glyph_info_t t = info[i];
    919 	  memmove (&info[i], &info[i + 1], (j - i) * sizeof (info[0]));
    920 	  info[j] = t;
    921 	}
    922         break;
    923       }
    924   }
    925 
    926   /* Attach misc marks to previous char to move with them. */
    927   {
    928     indic_position_t last_pos = POS_START;
    929     for (unsigned int i = start; i < end; i++)
    930     {
    931       if ((FLAG_SAFE (info[i].indic_category()) & (JOINER_FLAGS | FLAG (OT_N) | FLAG (OT_RS) | MEDIAL_FLAGS | HALANT_OR_COENG_FLAGS)))
    932       {
    933 	info[i].indic_position() = last_pos;
    934 	if (unlikely (info[i].indic_category() == OT_H &&
    935 		      info[i].indic_position() == POS_PRE_M))
    936 	{
    937 	  /*
    938 	   * Uniscribe doesn't move the Halant with Left Matra.
    939 	   * TEST: U+092B,U+093F,U+094DE
    940 	   * We follow.  This is important for the Sinhala
    941 	   * U+0DDA split matra since it decomposes to U+0DD9,U+0DCA
    942 	   * where U+0DD9 is a left matra and U+0DCA is the virama.
    943 	   * We don't want to move the virama with the left matra.
    944 	   * TEST: U+0D9A,U+0DDA
    945 	   */
    946 	  for (unsigned int j = i; j > start; j--)
    947 	    if (info[j - 1].indic_position() != POS_PRE_M) {
    948 	      info[i].indic_position() = info[j - 1].indic_position();
    949 	      break;
    950 	    }
    951 	}
    952       } else if (info[i].indic_position() != POS_SMVD) {
    953         last_pos = (indic_position_t) info[i].indic_position();
    954       }
    955     }
    956   }
    957   /* For post-base consonants let them own anything before them
    958    * since the last consonant or matra. */
    959   {
    960     unsigned int last = base;
    961     for (unsigned int i = base + 1; i < end; i++)
    962       if (is_consonant (info[i]))
    963       {
    964 	for (unsigned int j = last + 1; j < i; j++)
    965 	  if (info[j].indic_position() < POS_SMVD)
    966 	    info[j].indic_position() = info[i].indic_position();
    967 	last = i;
    968       } else if (info[i].indic_category() == OT_M)
    969         last = i;
    970   }
    971 
    972 
    973   {
    974     /* Use syllable() for sort accounting temporarily. */
    975     unsigned int syllable = info[start].syllable();
    976     for (unsigned int i = start; i < end; i++)
    977       info[i].syllable() = i - start;
    978 
    979     /* Sit tight, rock 'n roll! */
    980     hb_stable_sort (info + start, end - start, compare_indic_order);
    981     /* Find base again */
    982     base = end;
    983     for (unsigned int i = start; i < end; i++)
    984       if (info[i].indic_position() == POS_BASE_C)
    985       {
    986 	base = i;
    987 	break;
    988       }
    989     /* Things are out-of-control for post base positions, they may shuffle
    990      * around like crazy.  In old-spec mode, we move halants around, so in
    991      * that case merge all clusters after base.  Otherwise, check the sort
    992      * order and merge as needed.
    993      * For pre-base stuff, we handle cluster issues in final reordering.
    994      *
    995      * We could use buffer->sort() for this, if there was no special
    996      * reordering of pre-base stuff happening later...
    997      */
    998     if (indic_plan->is_old_spec || end - base > 127)
    999       buffer->merge_clusters (base, end);
   1000     else
   1001     {
   1002       /* Note!  syllable() is a one-byte field. */
   1003       for (unsigned int i = base; i < end; i++)
   1004         if (info[i].syllable() != 255)
   1005 	{
   1006 	  unsigned int max = i;
   1007 	  unsigned int j = start + info[i].syllable();
   1008 	  while (j != i)
   1009 	  {
   1010 	    max = MAX (max, j);
   1011 	    unsigned int next = start + info[j].syllable();
   1012 	    info[j].syllable() = 255; /* So we don't process j later again. */
   1013 	    j = next;
   1014 	  }
   1015 	  if (i != max)
   1016 	    buffer->merge_clusters (i, max + 1);
   1017 	}
   1018     }
   1019 
   1020     /* Put syllable back in. */
   1021     for (unsigned int i = start; i < end; i++)
   1022       info[i].syllable() = syllable;
   1023   }
   1024 
   1025   /* Setup masks now */
   1026 
   1027   {
   1028     hb_mask_t mask;
   1029 
   1030     /* Reph */
   1031     for (unsigned int i = start; i < end && info[i].indic_position() == POS_RA_TO_BECOME_REPH; i++)
   1032       info[i].mask |= indic_plan->mask_array[RPHF];
   1033 
   1034     /* Pre-base */
   1035     mask = indic_plan->mask_array[HALF];
   1036     if (!indic_plan->is_old_spec &&
   1037 	indic_plan->config->blwf_mode == BLWF_MODE_PRE_AND_POST)
   1038       mask |= indic_plan->mask_array[BLWF];
   1039     for (unsigned int i = start; i < base; i++)
   1040       info[i].mask  |= mask;
   1041     /* Base */
   1042     mask = 0;
   1043     if (base < end)
   1044       info[base].mask |= mask;
   1045     /* Post-base */
   1046     mask = indic_plan->mask_array[BLWF] | indic_plan->mask_array[ABVF] | indic_plan->mask_array[PSTF];
   1047     for (unsigned int i = base + 1; i < end; i++)
   1048       info[i].mask  |= mask;
   1049   }
   1050 
   1051   if (indic_plan->is_old_spec &&
   1052       buffer->props.script == HB_SCRIPT_DEVANAGARI)
   1053   {
   1054     /* Old-spec eye-lash Ra needs special handling.  From the
   1055      * spec:
   1056      *
   1057      * "The feature 'below-base form' is applied to consonants
   1058      * having below-base forms and following the base consonant.
   1059      * The exception is vattu, which may appear below half forms
   1060      * as well as below the base glyph. The feature 'below-base
   1061      * form' will be applied to all such occurrences of Ra as well."
   1062      *
   1063      * Test case: U+0924,U+094D,U+0930,U+094d,U+0915
   1064      * with Sanskrit 2003 font.
   1065      *
   1066      * However, note that Ra,Halant,ZWJ is the correct way to
   1067      * request eyelash form of Ra, so we wouldbn't inhibit it
   1068      * in that sequence.
   1069      *
   1070      * Test case: U+0924,U+094D,U+0930,U+094d,U+200D,U+0915
   1071      */
   1072     for (unsigned int i = start; i + 1 < base; i++)
   1073       if (info[i  ].indic_category() == OT_Ra &&
   1074 	  info[i+1].indic_category() == OT_H  &&
   1075 	  (i + 2 == base ||
   1076 	   info[i+2].indic_category() != OT_ZWJ))
   1077       {
   1078 	info[i  ].mask |= indic_plan->mask_array[BLWF];
   1079 	info[i+1].mask |= indic_plan->mask_array[BLWF];
   1080       }
   1081   }
   1082 
   1083   unsigned int pref_len = 2;
   1084   if (indic_plan->mask_array[PREF] && base + pref_len < end)
   1085   {
   1086     /* Find a Halant,Ra sequence and mark it for pre-base reordering processing. */
   1087     for (unsigned int i = base + 1; i + pref_len - 1 < end; i++) {
   1088       hb_codepoint_t glyphs[2];
   1089       for (unsigned int j = 0; j < pref_len; j++)
   1090         glyphs[j] = info[i + j].codepoint;
   1091       if (indic_plan->pref.would_substitute (glyphs, pref_len, face))
   1092       {
   1093 	for (unsigned int j = 0; j < pref_len; j++)
   1094 	  info[i++].mask |= indic_plan->mask_array[PREF];
   1095 
   1096 	/* Mark the subsequent stuff with 'cfar'.  Used in Khmer.
   1097 	 * Read the feature spec.
   1098 	 * This allows distinguishing the following cases with MS Khmer fonts:
   1099 	 * U+1784,U+17D2,U+179A,U+17D2,U+1782
   1100 	 * U+1784,U+17D2,U+1782,U+17D2,U+179A
   1101 	 */
   1102 	if (indic_plan->mask_array[CFAR])
   1103 	  for (; i < end; i++)
   1104 	    info[i].mask |= indic_plan->mask_array[CFAR];
   1105 
   1106 	break;
   1107       }
   1108     }
   1109   }
   1110 
   1111   /* Apply ZWJ/ZWNJ effects */
   1112   for (unsigned int i = start + 1; i < end; i++)
   1113     if (is_joiner (info[i])) {
   1114       bool non_joiner = info[i].indic_category() == OT_ZWNJ;
   1115       unsigned int j = i;
   1116 
   1117       do {
   1118 	j--;
   1119 
   1120 	/* ZWJ/ZWNJ should disable CJCT.  They do that by simply
   1121 	 * being there, since we don't skip them for the CJCT
   1122 	 * feature (ie. F_MANUAL_ZWJ) */
   1123 
   1124 	/* A ZWNJ disables HALF. */
   1125 	if (non_joiner)
   1126 	  info[j].mask &= ~indic_plan->mask_array[HALF];
   1127 
   1128       } while (j > start && !is_consonant (info[j]));
   1129     }
   1130 }
   1131 
   1132 static void
   1133 initial_reordering_standalone_cluster (const hb_ot_shape_plan_t *plan,
   1134 				       hb_face_t *face,
   1135 				       hb_buffer_t *buffer,
   1136 				       unsigned int start, unsigned int end)
   1137 {
   1138   /* We treat placeholder/dotted-circle as if they are consonants, so we
   1139    * should just chain.  Only if not in compatibility mode that is... */
   1140 
   1141   if (hb_options ().uniscribe_bug_compatible)
   1142   {
   1143     /* For dotted-circle, this is what Uniscribe does:
   1144      * If dotted-circle is the last glyph, it just does nothing.
   1145      * Ie. It doesn't form Reph. */
   1146     if (buffer->info[end - 1].indic_category() == OT_DOTTEDCIRCLE)
   1147       return;
   1148   }
   1149 
   1150   initial_reordering_consonant_syllable (plan, face, buffer, start, end);
   1151 }
   1152 
   1153 static void
   1154 initial_reordering_syllable (const hb_ot_shape_plan_t *plan,
   1155 			     hb_face_t *face,
   1156 			     hb_buffer_t *buffer,
   1157 			     unsigned int start, unsigned int end)
   1158 {
   1159   syllable_type_t syllable_type = (syllable_type_t) (buffer->info[start].syllable() & 0x0F);
   1160   switch (syllable_type)
   1161   {
   1162     case vowel_syllable: /* We made the vowels look like consonants.  So let's call the consonant logic! */
   1163     case consonant_syllable:
   1164      initial_reordering_consonant_syllable (plan, face, buffer, start, end);
   1165      break;
   1166 
   1167     case broken_cluster: /* We already inserted dotted-circles, so just call the standalone_cluster. */
   1168     case standalone_cluster:
   1169      initial_reordering_standalone_cluster (plan, face, buffer, start, end);
   1170      break;
   1171 
   1172     case symbol_cluster:
   1173     case non_indic_cluster:
   1174       break;
   1175   }
   1176 }
   1177 
   1178 static inline void
   1179 insert_dotted_circles (const hb_ot_shape_plan_t *plan HB_UNUSED,
   1180 		       hb_font_t *font,
   1181 		       hb_buffer_t *buffer)
   1182 {
   1183   /* Note: This loop is extra overhead, but should not be measurable. */
   1184   bool has_broken_syllables = false;
   1185   unsigned int count = buffer->len;
   1186   hb_glyph_info_t *info = buffer->info;
   1187   for (unsigned int i = 0; i < count; i++)
   1188     if ((info[i].syllable() & 0x0F) == broken_cluster)
   1189     {
   1190       has_broken_syllables = true;
   1191       break;
   1192     }
   1193   if (likely (!has_broken_syllables))
   1194     return;
   1195 
   1196 
   1197   hb_codepoint_t dottedcircle_glyph;
   1198   if (!font->get_nominal_glyph (0x25CCu, &dottedcircle_glyph))
   1199     return;
   1200 
   1201   hb_glyph_info_t dottedcircle = {0};
   1202   dottedcircle.codepoint = 0x25CCu;
   1203   set_indic_properties (dottedcircle);
   1204   dottedcircle.codepoint = dottedcircle_glyph;
   1205 
   1206   buffer->clear_output ();
   1207 
   1208   buffer->idx = 0;
   1209   unsigned int last_syllable = 0;
   1210   while (buffer->idx < buffer->len && !buffer->in_error)
   1211   {
   1212     unsigned int syllable = buffer->cur().syllable();
   1213     syllable_type_t syllable_type = (syllable_type_t) (syllable & 0x0F);
   1214     if (unlikely (last_syllable != syllable && syllable_type == broken_cluster))
   1215     {
   1216       last_syllable = syllable;
   1217 
   1218       hb_glyph_info_t ginfo = dottedcircle;
   1219       ginfo.cluster = buffer->cur().cluster;
   1220       ginfo.mask = buffer->cur().mask;
   1221       ginfo.syllable() = buffer->cur().syllable();
   1222       /* TODO Set glyph_props? */
   1223 
   1224       /* Insert dottedcircle after possible Repha. */
   1225       while (buffer->idx < buffer->len && !buffer->in_error &&
   1226 	     last_syllable == buffer->cur().syllable() &&
   1227 	     buffer->cur().indic_category() == OT_Repha)
   1228         buffer->next_glyph ();
   1229 
   1230       buffer->output_info (ginfo);
   1231     }
   1232     else
   1233       buffer->next_glyph ();
   1234   }
   1235 
   1236   buffer->swap_buffers ();
   1237 }
   1238 
   1239 static void
   1240 initial_reordering (const hb_ot_shape_plan_t *plan,
   1241 		    hb_font_t *font,
   1242 		    hb_buffer_t *buffer)
   1243 {
   1244   update_consonant_positions (plan, font, buffer);
   1245   insert_dotted_circles (plan, font, buffer);
   1246 
   1247   foreach_syllable (buffer, start, end)
   1248     initial_reordering_syllable (plan, font->face, buffer, start, end);
   1249 }
   1250 
   1251 static void
   1252 final_reordering_syllable (const hb_ot_shape_plan_t *plan,
   1253 			   hb_buffer_t *buffer,
   1254 			   unsigned int start, unsigned int end)
   1255 {
   1256   const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
   1257   hb_glyph_info_t *info = buffer->info;
   1258 
   1259 
   1260   /* This function relies heavily on halant glyphs.  Lots of ligation
   1261    * and possibly multiplication substitutions happened prior to this
   1262    * phase, and that might have messed up our properties.  Recover
   1263    * from a particular case of that where we're fairly sure that a
   1264    * class of OT_H is desired but has been lost. */
   1265   if (indic_plan->virama_glyph)
   1266   {
   1267     unsigned int virama_glyph = indic_plan->virama_glyph;
   1268     for (unsigned int i = start; i < end; i++)
   1269       if (info[i].codepoint == virama_glyph &&
   1270 	  _hb_glyph_info_ligated (&info[i]) &&
   1271 	  _hb_glyph_info_multiplied (&info[i]))
   1272       {
   1273         /* This will make sure that this glyph passes is_halant_or_coeng() test. */
   1274 	info[i].indic_category() = OT_H;
   1275 	_hb_glyph_info_clear_ligated_and_multiplied (&info[i]);
   1276       }
   1277   }
   1278 
   1279 
   1280   /* 4. Final reordering:
   1281    *
   1282    * After the localized forms and basic shaping forms GSUB features have been
   1283    * applied (see below), the shaping engine performs some final glyph
   1284    * reordering before applying all the remaining font features to the entire
   1285    * cluster.
   1286    */
   1287 
   1288   bool try_pref = !!indic_plan->mask_array[PREF];
   1289 
   1290   /* Find base again */
   1291   unsigned int base;
   1292   for (base = start; base < end; base++)
   1293     if (info[base].indic_position() >= POS_BASE_C)
   1294     {
   1295       if (try_pref && base + 1 < end)
   1296       {
   1297 	for (unsigned int i = base + 1; i < end; i++)
   1298 	  if ((info[i].mask & indic_plan->mask_array[PREF]) != 0)
   1299 	  {
   1300 	    if (!(_hb_glyph_info_substituted (&info[i]) &&
   1301 		  _hb_glyph_info_ligated_and_didnt_multiply (&info[i])))
   1302 	    {
   1303 	      /* Ok, this was a 'pref' candidate but didn't form any.
   1304 	       * Base is around here... */
   1305 	      base = i;
   1306 	      while (base < end && is_halant_or_coeng (info[base]))
   1307 		base++;
   1308 	      info[base].indic_position() = POS_BASE_C;
   1309 
   1310 	      try_pref = false;
   1311 	    }
   1312 	    break;
   1313 	  }
   1314       }
   1315       /* For Malayalam, skip over unformed below- (but NOT post-) forms. */
   1316       if (buffer->props.script == HB_SCRIPT_MALAYALAM)
   1317       {
   1318 	for (unsigned int i = base + 1; i < end; i++)
   1319 	{
   1320 	  while (i < end && is_joiner (info[i]))
   1321 	    i++;
   1322 	  if (i == end || !is_halant_or_coeng (info[i]))
   1323 	    break;
   1324 	  i++; /* Skip halant. */
   1325 	  while (i < end && is_joiner (info[i]))
   1326 	    i++;
   1327 	  if (i < end && is_consonant (info[i]) && info[i].indic_position() == POS_BELOW_C)
   1328 	  {
   1329 	    base = i;
   1330 	    info[base].indic_position() = POS_BASE_C;
   1331 	  }
   1332 	}
   1333       }
   1334 
   1335       if (start < base && info[base].indic_position() > POS_BASE_C)
   1336         base--;
   1337       break;
   1338     }
   1339   if (base == end && start < base &&
   1340       is_one_of (info[base - 1], FLAG (OT_ZWJ)))
   1341     base--;
   1342   if (base < end)
   1343     while (start < base &&
   1344 	   is_one_of (info[base], (FLAG (OT_N) | HALANT_OR_COENG_FLAGS)))
   1345       base--;
   1346 
   1347 
   1348   /*   o Reorder matras:
   1349    *
   1350    *     If a pre-base matra character had been reordered before applying basic
   1351    *     features, the glyph can be moved closer to the main consonant based on
   1352    *     whether half-forms had been formed. Actual position for the matra is
   1353    *     defined as after last standalone halant glyph, after initial matra
   1354    *     position and before the main consonant. If ZWJ or ZWNJ follow this
   1355    *     halant, position is moved after it.
   1356    */
   1357 
   1358   if (start + 1 < end && start < base) /* Otherwise there can't be any pre-base matra characters. */
   1359   {
   1360     /* If we lost track of base, alas, position before last thingy. */
   1361     unsigned int new_pos = base == end ? base - 2 : base - 1;
   1362 
   1363     /* Malayalam / Tamil do not have "half" forms or explicit virama forms.
   1364      * The glyphs formed by 'half' are Chillus or ligated explicit viramas.
   1365      * We want to position matra after them.
   1366      */
   1367     if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL)
   1368     {
   1369       while (new_pos > start &&
   1370 	     !(is_one_of (info[new_pos], (FLAG (OT_M) | HALANT_OR_COENG_FLAGS))))
   1371 	new_pos--;
   1372 
   1373       /* If we found no Halant we are done.
   1374        * Otherwise only proceed if the Halant does
   1375        * not belong to the Matra itself! */
   1376       if (is_halant_or_coeng (info[new_pos]) &&
   1377 	  info[new_pos].indic_position() != POS_PRE_M)
   1378       {
   1379 	/* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
   1380 	if (new_pos + 1 < end && is_joiner (info[new_pos + 1]))
   1381 	  new_pos++;
   1382       }
   1383       else
   1384         new_pos = start; /* No move. */
   1385     }
   1386 
   1387     if (start < new_pos && info[new_pos].indic_position () != POS_PRE_M)
   1388     {
   1389       /* Now go see if there's actually any matras... */
   1390       for (unsigned int i = new_pos; i > start; i--)
   1391 	if (info[i - 1].indic_position () == POS_PRE_M)
   1392 	{
   1393 	  unsigned int old_pos = i - 1;
   1394 	  if (old_pos < base && base <= new_pos) /* Shouldn't actually happen. */
   1395 	    base--;
   1396 
   1397 	  hb_glyph_info_t tmp = info[old_pos];
   1398 	  memmove (&info[old_pos], &info[old_pos + 1], (new_pos - old_pos) * sizeof (info[0]));
   1399 	  info[new_pos] = tmp;
   1400 
   1401 	  /* Note: this merge_clusters() is intentionally *after* the reordering.
   1402 	   * Indic matra reordering is special and tricky... */
   1403 	  buffer->merge_clusters (new_pos, MIN (end, base + 1));
   1404 
   1405 	  new_pos--;
   1406 	}
   1407     } else {
   1408       for (unsigned int i = start; i < base; i++)
   1409 	if (info[i].indic_position () == POS_PRE_M) {
   1410 	  buffer->merge_clusters (i, MIN (end, base + 1));
   1411 	  break;
   1412 	}
   1413     }
   1414   }
   1415 
   1416 
   1417   /*   o Reorder reph:
   1418    *
   1419    *     Rephs original position is always at the beginning of the syllable,
   1420    *     (i.e. it is not reordered at the character reordering stage). However,
   1421    *     it will be reordered according to the basic-forms shaping results.
   1422    *     Possible positions for reph, depending on the script, are; after main,
   1423    *     before post-base consonant forms, and after post-base consonant forms.
   1424    */
   1425 
   1426   /* Two cases:
   1427    *
   1428    * - If repha is encoded as a sequence of characters (Ra,H or Ra,H,ZWJ), then
   1429    *   we should only move it if the sequence ligated to the repha form.
   1430    *
   1431    * - If repha is encoded separately and in the logical position, we should only
   1432    *   move it if it did NOT ligate.  If it ligated, it's probably the font trying
   1433    *   to make it work without the reordering.
   1434    */
   1435   if (start + 1 < end &&
   1436       info[start].indic_position() == POS_RA_TO_BECOME_REPH &&
   1437       ((info[start].indic_category() == OT_Repha) ^
   1438        _hb_glyph_info_ligated_and_didnt_multiply (&info[start])))
   1439   {
   1440     unsigned int new_reph_pos;
   1441     reph_position_t reph_pos = indic_plan->config->reph_pos;
   1442 
   1443     assert (reph_pos != REPH_POS_DONT_CARE);
   1444 
   1445     /*       1. If reph should be positioned after post-base consonant forms,
   1446      *          proceed to step 5.
   1447      */
   1448     if (reph_pos == REPH_POS_AFTER_POST)
   1449     {
   1450       goto reph_step_5;
   1451     }
   1452 
   1453     /*       2. If the reph repositioning class is not after post-base: target
   1454      *          position is after the first explicit halant glyph between the
   1455      *          first post-reph consonant and last main consonant. If ZWJ or ZWNJ
   1456      *          are following this halant, position is moved after it. If such
   1457      *          position is found, this is the target position. Otherwise,
   1458      *          proceed to the next step.
   1459      *
   1460      *          Note: in old-implementation fonts, where classifications were
   1461      *          fixed in shaping engine, there was no case where reph position
   1462      *          will be found on this step.
   1463      */
   1464     {
   1465       new_reph_pos = start + 1;
   1466       while (new_reph_pos < base && !is_halant_or_coeng (info[new_reph_pos]))
   1467 	new_reph_pos++;
   1468 
   1469       if (new_reph_pos < base && is_halant_or_coeng (info[new_reph_pos]))
   1470       {
   1471 	/* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */
   1472 	if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1]))
   1473 	  new_reph_pos++;
   1474 	goto reph_move;
   1475       }
   1476     }
   1477 
   1478     /*       3. If reph should be repositioned after the main consonant: find the
   1479      *          first consonant not ligated with main, or find the first
   1480      *          consonant that is not a potential pre-base reordering Ra.
   1481      */
   1482     if (reph_pos == REPH_POS_AFTER_MAIN)
   1483     {
   1484       new_reph_pos = base;
   1485       while (new_reph_pos + 1 < end && info[new_reph_pos + 1].indic_position() <= POS_AFTER_MAIN)
   1486 	new_reph_pos++;
   1487       if (new_reph_pos < end)
   1488         goto reph_move;
   1489     }
   1490 
   1491     /*       4. If reph should be positioned before post-base consonant, find
   1492      *          first post-base classified consonant not ligated with main. If no
   1493      *          consonant is found, the target position should be before the
   1494      *          first matra, syllable modifier sign or vedic sign.
   1495      */
   1496     /* This is our take on what step 4 is trying to say (and failing, BADLY). */
   1497     if (reph_pos == REPH_POS_AFTER_SUB)
   1498     {
   1499       new_reph_pos = base;
   1500       while (new_reph_pos < end &&
   1501 	     !( FLAG_SAFE (info[new_reph_pos + 1].indic_position()) & (FLAG (POS_POST_C) | FLAG (POS_AFTER_POST) | FLAG (POS_SMVD))))
   1502 	new_reph_pos++;
   1503       if (new_reph_pos < end)
   1504         goto reph_move;
   1505     }
   1506 
   1507     /*       5. If no consonant is found in steps 3 or 4, move reph to a position
   1508      *          immediately before the first post-base matra, syllable modifier
   1509      *          sign or vedic sign that has a reordering class after the intended
   1510      *          reph position. For example, if the reordering position for reph
   1511      *          is post-main, it will skip above-base matras that also have a
   1512      *          post-main position.
   1513      */
   1514     reph_step_5:
   1515     {
   1516       /* Copied from step 2. */
   1517       new_reph_pos = start + 1;
   1518       while (new_reph_pos < base && !is_halant_or_coeng (info[new_reph_pos]))
   1519 	new_reph_pos++;
   1520 
   1521       if (new_reph_pos < base && is_halant_or_coeng (info[new_reph_pos]))
   1522       {
   1523 	/* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */
   1524 	if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1]))
   1525 	  new_reph_pos++;
   1526 	goto reph_move;
   1527       }
   1528     }
   1529 
   1530     /*       6. Otherwise, reorder reph to the end of the syllable.
   1531      */
   1532     {
   1533       new_reph_pos = end - 1;
   1534       while (new_reph_pos > start && info[new_reph_pos].indic_position() == POS_SMVD)
   1535 	new_reph_pos--;
   1536 
   1537       /*
   1538        * If the Reph is to be ending up after a Matra,Halant sequence,
   1539        * position it before that Halant so it can interact with the Matra.
   1540        * However, if it's a plain Consonant,Halant we shouldn't do that.
   1541        * Uniscribe doesn't do this.
   1542        * TEST: U+0930,U+094D,U+0915,U+094B,U+094D
   1543        */
   1544       if (!hb_options ().uniscribe_bug_compatible &&
   1545 	  unlikely (is_halant_or_coeng (info[new_reph_pos]))) {
   1546 	for (unsigned int i = base + 1; i < new_reph_pos; i++)
   1547 	  if (info[i].indic_category() == OT_M) {
   1548 	    /* Ok, got it. */
   1549 	    new_reph_pos--;
   1550 	  }
   1551       }
   1552       goto reph_move;
   1553     }
   1554 
   1555     reph_move:
   1556     {
   1557       /* Move */
   1558       buffer->merge_clusters (start, new_reph_pos + 1);
   1559       hb_glyph_info_t reph = info[start];
   1560       memmove (&info[start], &info[start + 1], (new_reph_pos - start) * sizeof (info[0]));
   1561       info[new_reph_pos] = reph;
   1562 
   1563       if (start < base && base <= new_reph_pos)
   1564 	base--;
   1565     }
   1566   }
   1567 
   1568 
   1569   /*   o Reorder pre-base reordering consonants:
   1570    *
   1571    *     If a pre-base reordering consonant is found, reorder it according to
   1572    *     the following rules:
   1573    */
   1574 
   1575   if (try_pref && base + 1 < end) /* Otherwise there can't be any pre-base reordering Ra. */
   1576   {
   1577     for (unsigned int i = base + 1; i < end; i++)
   1578       if ((info[i].mask & indic_plan->mask_array[PREF]) != 0)
   1579       {
   1580 	/*       1. Only reorder a glyph produced by substitution during application
   1581 	 *          of the <pref> feature. (Note that a font may shape a Ra consonant with
   1582 	 *          the feature generally but block it in certain contexts.)
   1583 	 */
   1584         /* Note: We just check that something got substituted.  We don't check that
   1585 	 * the <pref> feature actually did it...
   1586 	 *
   1587 	 * Reorder pref only if it ligated. */
   1588 	if (_hb_glyph_info_ligated_and_didnt_multiply (&info[i]))
   1589 	{
   1590 	  /*
   1591 	   *       2. Try to find a target position the same way as for pre-base matra.
   1592 	   *          If it is found, reorder pre-base consonant glyph.
   1593 	   *
   1594 	   *       3. If position is not found, reorder immediately before main
   1595 	   *          consonant.
   1596 	   */
   1597 
   1598 	  unsigned int new_pos = base;
   1599 	  /* Malayalam / Tamil do not have "half" forms or explicit virama forms.
   1600 	   * The glyphs formed by 'half' are Chillus or ligated explicit viramas.
   1601 	   * We want to position matra after them.
   1602 	   */
   1603 	  if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL)
   1604 	  {
   1605 	    while (new_pos > start &&
   1606 		   !(is_one_of (info[new_pos - 1], FLAG(OT_M) | HALANT_OR_COENG_FLAGS)))
   1607 	      new_pos--;
   1608 
   1609 	    /* In Khmer coeng model, a H,Ra can go *after* matras.  If it goes after a
   1610 	     * split matra, it should be reordered to *before* the left part of such matra. */
   1611 	    if (new_pos > start && info[new_pos - 1].indic_category() == OT_M)
   1612 	    {
   1613 	      unsigned int old_pos = i;
   1614 	      for (unsigned int j = base + 1; j < old_pos; j++)
   1615 		if (info[j].indic_category() == OT_M)
   1616 		{
   1617 		  new_pos--;
   1618 		  break;
   1619 		}
   1620 	    }
   1621 	  }
   1622 
   1623 	  if (new_pos > start && is_halant_or_coeng (info[new_pos - 1]))
   1624 	  {
   1625 	    /* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
   1626 	    if (new_pos < end && is_joiner (info[new_pos]))
   1627 	      new_pos++;
   1628 	  }
   1629 
   1630 	  {
   1631 	    unsigned int old_pos = i;
   1632 
   1633 	    buffer->merge_clusters (new_pos, old_pos + 1);
   1634 	    hb_glyph_info_t tmp = info[old_pos];
   1635 	    memmove (&info[new_pos + 1], &info[new_pos], (old_pos - new_pos) * sizeof (info[0]));
   1636 	    info[new_pos] = tmp;
   1637 
   1638 	    if (new_pos <= base && base < old_pos)
   1639 	      base++;
   1640 	  }
   1641 	}
   1642 
   1643         break;
   1644       }
   1645   }
   1646 
   1647 
   1648   /* Apply 'init' to the Left Matra if it's a word start. */
   1649   if (info[start].indic_position () == POS_PRE_M &&
   1650       (!start ||
   1651        !(FLAG_SAFE (_hb_glyph_info_get_general_category (&info[start - 1])) &
   1652 	 FLAG_RANGE (HB_UNICODE_GENERAL_CATEGORY_FORMAT, HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK))))
   1653     info[start].mask |= indic_plan->mask_array[INIT];
   1654 
   1655 
   1656   /*
   1657    * Finish off the clusters and go home!
   1658    */
   1659   if (hb_options ().uniscribe_bug_compatible)
   1660   {
   1661     switch ((hb_tag_t) plan->props.script)
   1662     {
   1663       case HB_SCRIPT_TAMIL:
   1664       case HB_SCRIPT_SINHALA:
   1665         break;
   1666 
   1667       default:
   1668 	/* Uniscribe merges the entire cluster... Except for Tamil & Sinhala.
   1669 	 * This means, half forms are submerged into the main consonants cluster.
   1670 	 * This is unnecessary, and makes cursor positioning harder, but that's what
   1671 	 * Uniscribe does. */
   1672 	buffer->merge_clusters (start, end);
   1673 	break;
   1674     }
   1675   }
   1676 }
   1677 
   1678 
   1679 static void
   1680 final_reordering (const hb_ot_shape_plan_t *plan,
   1681 		  hb_font_t *font HB_UNUSED,
   1682 		  hb_buffer_t *buffer)
   1683 {
   1684   unsigned int count = buffer->len;
   1685   if (unlikely (!count)) return;
   1686 
   1687   foreach_syllable (buffer, start, end)
   1688     final_reordering_syllable (plan, buffer, start, end);
   1689 
   1690   HB_BUFFER_DEALLOCATE_VAR (buffer, indic_category);
   1691   HB_BUFFER_DEALLOCATE_VAR (buffer, indic_position);
   1692 }
   1693 
   1694 
   1695 static void
   1696 clear_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
   1697 		 hb_font_t *font HB_UNUSED,
   1698 		 hb_buffer_t *buffer)
   1699 {
   1700   hb_glyph_info_t *info = buffer->info;
   1701   unsigned int count = buffer->len;
   1702   for (unsigned int i = 0; i < count; i++)
   1703     info[i].syllable() = 0;
   1704 }
   1705 
   1706 
   1707 static bool
   1708 decompose_indic (const hb_ot_shape_normalize_context_t *c,
   1709 		 hb_codepoint_t  ab,
   1710 		 hb_codepoint_t *a,
   1711 		 hb_codepoint_t *b)
   1712 {
   1713   switch (ab)
   1714   {
   1715     /* Don't decompose these. */
   1716     case 0x0931u  : return false; /* DEVANAGARI LETTER RRA */
   1717     case 0x0B94u  : return false; /* TAMIL LETTER AU */
   1718 
   1719 
   1720     /*
   1721      * Decompose split matras that don't have Unicode decompositions.
   1722      */
   1723 
   1724     /* Khmer */
   1725     case 0x17BEu  : *a = 0x17C1u; *b= 0x17BEu; return true;
   1726     case 0x17BFu  : *a = 0x17C1u; *b= 0x17BFu; return true;
   1727     case 0x17C0u  : *a = 0x17C1u; *b= 0x17C0u; return true;
   1728     case 0x17C4u  : *a = 0x17C1u; *b= 0x17C4u; return true;
   1729     case 0x17C5u  : *a = 0x17C1u; *b= 0x17C5u; return true;
   1730 
   1731 #if 0
   1732     /* Gujarati */
   1733     /* This one has no decomposition in Unicode, but needs no decomposition either. */
   1734     /* case 0x0AC9u  : return false; */
   1735 
   1736     /* Oriya */
   1737     case 0x0B57u  : *a = no decomp, -> RIGHT; return true;
   1738 #endif
   1739   }
   1740 
   1741   if ((ab == 0x0DDAu || hb_in_range (ab, 0x0DDCu, 0x0DDEu)))
   1742   {
   1743     /*
   1744      * Sinhala split matras...  Let the fun begin.
   1745      *
   1746      * These four characters have Unicode decompositions.  However, Uniscribe
   1747      * decomposes them "Khmer-style", that is, it uses the character itself to
   1748      * get the second half.  The first half of all four decompositions is always
   1749      * U+0DD9.
   1750      *
   1751      * Now, there are buggy fonts, namely, the widely used lklug.ttf, that are
   1752      * broken with Uniscribe.  But we need to support them.  As such, we only
   1753      * do the Uniscribe-style decomposition if the character is transformed into
   1754      * its "sec.half" form by the 'pstf' feature.  Otherwise, we fall back to
   1755      * Unicode decomposition.
   1756      *
   1757      * Note that we can't unconditionally use Unicode decomposition.  That would
   1758      * break some other fonts, that are designed to work with Uniscribe, and
   1759      * don't have positioning features for the Unicode-style decomposition.
   1760      *
   1761      * Argh...
   1762      *
   1763      * The Uniscribe behavior is now documented in the newly published Sinhala
   1764      * spec in 2012:
   1765      *
   1766      *   http://www.microsoft.com/typography/OpenTypeDev/sinhala/intro.htm#shaping
   1767      */
   1768 
   1769     const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) c->plan->data;
   1770 
   1771     hb_codepoint_t glyph;
   1772 
   1773     if (hb_options ().uniscribe_bug_compatible ||
   1774 	(c->font->get_nominal_glyph (ab, &glyph) &&
   1775 	 indic_plan->pstf.would_substitute (&glyph, 1, c->font->face)))
   1776     {
   1777       /* Ok, safe to use Uniscribe-style decomposition. */
   1778       *a = 0x0DD9u;
   1779       *b = ab;
   1780       return true;
   1781     }
   1782   }
   1783 
   1784   return (bool) c->unicode->decompose (ab, a, b);
   1785 }
   1786 
   1787 static bool
   1788 compose_indic (const hb_ot_shape_normalize_context_t *c,
   1789 	       hb_codepoint_t  a,
   1790 	       hb_codepoint_t  b,
   1791 	       hb_codepoint_t *ab)
   1792 {
   1793   /* Avoid recomposing split matras. */
   1794   if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a)))
   1795     return false;
   1796 
   1797   /* Composition-exclusion exceptions that we want to recompose. */
   1798   if (a == 0x09AFu && b == 0x09BCu) { *ab = 0x09DFu; return true; }
   1799 
   1800   return (bool) c->unicode->compose (a, b, ab);
   1801 }
   1802 
   1803 
   1804 const hb_ot_complex_shaper_t _hb_ot_complex_shaper_indic =
   1805 {
   1806   "indic",
   1807   collect_features_indic,
   1808   override_features_indic,
   1809   data_create_indic,
   1810   data_destroy_indic,
   1811   NULL, /* preprocess_text */
   1812   NULL, /* postprocess_glyphs */
   1813   HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,
   1814   decompose_indic,
   1815   compose_indic,
   1816   setup_masks_indic,
   1817   NULL, /* disable_otl */
   1818   HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE,
   1819   false, /* fallback_position */
   1820 };
   1821