src/otlayout/otlcommn.c - third_party/freetype2 - Git at Google

 /***************************************************************************/
 /*                                                                         */
 /*  otlcommn.c                                                             */
 /*                                                                         */
 /*    OpenType layout support, common tables (body).                       */
 /*                                                                         */
 /*  Copyright 2002 by                                                      */
 /*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
 /*                                                                         */
 /*  This file is part of the FreeType project, and may only be used,       */
 /*  modified, and distributed under the terms of the FreeType project      */
 /*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
 /*  this file you indicate that you have read the license and              */
 /*  understand and accept it fully.                                        */
 /*                                                                         */
 /***************************************************************************/


 #include "otlayout.h"


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                       COVERAGE TABLE                          *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

   OTL_LOCALDEF( void )
   otl_coverage_validate( OTL_Bytes      table,
                          OTL_Validator  valid )
   {
     OTL_Bytes  p;
     OTL_UInt   format;


     if ( table + 4 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     format = OTL_NEXT_USHORT( p );
     switch ( format )
     {
     case 1:
       {
         OTL_UInt  count = OTL_NEXT_USHORT( p );


         if ( p + count * 2 >= valid->limit )
           OTL_INVALID_TOO_SHORT;

         /* XXX: check glyph indices */
       }
       break;

     case 2:
       {
         OTL_UInt  n, num_ranges = OTL_NEXT_USHORT( p );
         OTL_UInt  start, end, start_cover, total = 0, last = 0;


         if ( p + num_ranges * 6 >= valid->limit )
           OTL_INVALID_TOO_SHORT;

         for ( n = 0; n < num_ranges; n++ )
         {
           start       = OTL_NEXT_USHORT( p );
           end         = OTL_NEXT_USHORT( p );
           start_cover = OTL_NEXT_USHORT( p );

           if ( start > end || start_cover != total )
             OTL_INVALID_DATA;

           if ( n > 0 && start <= last )
             OTL_INVALID_DATA;

           total += end - start + 1;
           last   = end;
         }
       }
       break;

     default:
       OTL_INVALID_FORMAT;
     }
   }


   OTL_LOCALDEF( OTL_UInt )
   otl_coverage_get_count( OTL_Bytes  table )
   {
     OTL_Bytes  p      = table;
     OTL_UInt   format = OTL_NEXT_USHORT( p );
     OTL_UInt   count  = OTL_NEXT_USHORT( p );
     OTL_UInt   result = 0;


     switch ( format )
     {
     case 1:
       return count;

     case 2:
       {
         OTL_UInt  start, end;


         for ( ; count > 0; count-- )
         {
           start = OTL_NEXT_USHORT( p );
           end   = OTL_NEXT_USHORT( p );
           p    += 2;                    /* skip start_index */

           result += end - start + 1;
         }
       }
       break;

     default:
       ;
     }

     return result;
   }


   OTL_LOCALDEF( OTL_Int )
   otl_coverage_get_index( OTL_Bytes  table,
                           OTL_UInt   glyph_index )
   {
     OTL_Bytes  p      = table;
     OTL_UInt   format = OTL_NEXT_USHORT( p );
     OTL_UInt   count  = OTL_NEXT_USHORT( p );


     switch ( format )
     {
     case 1:
       {
         OTL_UInt  min = 0, max = count, mid, gindex;


         table += 4;
         while ( min < max )
         {
           mid    = ( min + max ) >> 1;
           p      = table + 2 * mid;
           gindex = OTL_PEEK_USHORT( p );

           if ( glyph_index == gindex )
             return (OTL_Int)mid;

           if ( glyph_index < gindex )
             max = mid;
           else
             min = mid + 1;
         }
       }
       break;

     case 2:
       {
         OTL_UInt  min = 0, max = count, mid;
         OTL_UInt  start, end, delta, start_cover;


         table += 4;
         while ( min < max )
         {
           mid    = ( min + max ) >> 1;
           p      = table + 6 * mid;
           start  = OTL_NEXT_USHORT( p );
           end    = OTL_NEXT_USHORT( p );

           if ( glyph_index < start )
             max = mid;
           else if ( glyph_index > end )
             min = mid + 1;
           else
             return (OTL_Int)( glyph_index + OTL_NEXT_USHORT( p ) - start );
         }
       }
       break;

     default:
       ;
     }

     return -1;
   }


   /*************************************************************************/
   /*************************************************************************/
   /*****                                                               *****/
   /*****                  CLASS DEFINITION TABLE                       *****/
   /*****                                                               *****/
   /*************************************************************************/
   /*************************************************************************/

   OTL_LOCALDEF( void )
   otl_class_definition_validate( OTL_Bytes      table,
                                  OTL_Validator  valid )
   {
     OTL_Bytes  p = table;
     OTL_UInt   format;


     if ( p + 4 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     format = OTL_NEXT_USHORT( p );
     switch ( format )
     {
     case 1:
       {
         OTL_UInt  count, start = OTL_NEXT_USHORT( p );


         if ( p + 2 > valid->limit )
           OTL_INVALID_TOO_SHORT;

         count = OTL_NEXT_USHORT( p );

         if ( p + count * 2 > valid->limit )
           OTL_INVALID_TOO_SHORT;

         /* XXX: check glyph indices */
       }
       break;

     case 2:
       {
         OTL_UInt  n, num_ranges = OTL_NEXT_USHORT( p );
         OTL_UInt  start, end, value, last = 0;


         if ( p + num_ranges * 6 > valid->limit )
           OTL_INVALID_TOO_SHORT;

         for ( n = 0; n < num_ranges; n++ )
         {
           start = OTL_NEXT_USHORT( p );
           end   = OTL_NEXT_USHORT( p );
           value = OTL_NEXT_USHORT( p );  /* ignored */

           if ( start > end || ( n > 0 && start <= last ) )
             OTL_INVALID_DATA;

           last = end;
         }
       }
       break;

     default:
       OTL_INVALID_FORMAT;
     }
   }


   OTL_LOCALDEF( OTL_UInt )
   otl_class_definition_get_value( OTL_Bytes  table,
                                   OTL_UInt   glyph_index )
   {
     OTL_Bytes  p      = table;
     OTL_UInt   format = OTL_NEXT_USHORT( p );


     switch ( format )
     {
     case 1:
       {
         OTL_UInt  start = OTL_NEXT_USHORT( p );
         OTL_UInt  count = OTL_NEXT_USHORT( p );
         OTL_UInt  idx   = (OTL_UInt)( glyph_index - start );


         if ( idx < count )
         {
           p += 2 * idx;
           return OTL_PEEK_USHORT( p );
         }
       }
       break;

     case 2:
       {
         OTL_UInt  count = OTL_NEXT_USHORT( p );
         OTL_UInt  min = 0, max = count, mid, gindex;


         table += 4;
         while ( min < max )
         {
           mid   = ( min + max ) >> 1;
           p     = table + 6 * mid;
           start = OTL_NEXT_USHORT( p );
           end   = OTL_NEXT_USHORT( p );

           if ( glyph_index < start )
             max = mid;
           else if ( glyph_index > end )
             min = mid + 1;
           else
             return OTL_PEEK_USHORT( p );
         }
       }
       break;

     default:
       ;
     }

     return 0;
   }


   /*************************************************************************/
   /*************************************************************************/
   /*****                                                               *****/
   /*****                      DEVICE TABLE                             *****/
   /*****                                                               *****/
   /*************************************************************************/
   /*************************************************************************/

   OTL_LOCALDEF( void )
   otl_device_table_validate( OTL_Bytes      table,
                              OTL_Validator  valid )
   {
     OTL_Bytes  p = table;
     OTL_UInt   start, end, count, format, count;


     if ( p + 8 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     start  = OTL_NEXT_USHORT( p );
     end    = OTL_NEXT_USHORT( p );
     format = OTL_NEXT_USHORT( p );

     if ( format < 1 || format > 3 || end < start )
       OTL_INVALID_DATA;

     count = (OTL_UInt)( end - start + 1 );

     if ( p + ( ( 1 << format ) * count ) / 8 > valid->limit )
       OTL_INVALID_TOO_SHORT;
   }


   OTL_LOCALDEF( OTL_UInt )
   otl_device_table_get_start( OTL_Bytes  table )
   {
     OTL_Bytes  p = table;


     return OTL_PEEK_USHORT( p );
   }


   OTL_LOCALDEF( OTL_UInt )
   otl_device_table_get_end( OTL_Bytes  table )
   {
     OTL_Bytes  p = table + 2;


     return OTL_PEEK_USHORT( p );
   }


   OTL_LOCALDEF( OTL_Int )
   otl_device_table_get_delta( OTL_Bytes  table,
                               OTL_UInt   size )
   {
     OTL_Bytes  p = table;
     OTL_Int    result = 0;
     OTL_UInt   start, end, format, idx, value;


     start  = OTL_NEXT_USHORT( p );
     end    = OTL_NEXT_USHORT( p );
     format = OTL_NEXT_USHORT( p );

     if ( size >= start && size <= end )
     {
       /* we could do that with clever bit operations, but a switch is */
       /* much simpler to understand and maintain                      */
       /*                                                              */
       switch ( format )
       {
       case 1:
         idx    = (OTL_UInt)( ( size - start ) * 2 );
         p     += idx / 16;
         value  = OTL_PEEK_USHORT( p );
         shift  = idx & 15;
         result = (OTL_Short)( value << shift ) >> ( 14 - shift );

         break;

       case 2:
         idx    = (OTL_UInt)( ( size - start ) * 4 );
         p     += idx / 16;
         value  = OTL_PEEK_USHORT( p );
         shift  = idx & 15;
         result = (OTL_Short)( value << shift ) >> ( 12 - shift );

         break;

       case 3:
         idx    = (OTL_UInt)( ( size - start ) * 8 );
         p     += idx / 16;
         value  = OTL_PEEK_USHORT( p );
         shift  = idx & 15;
         result = (OTL_Short)( value << shift ) >> ( 8 - shift );

         break;

       default:
         ;
       }
     }

     return result;
   }


   /*************************************************************************/
   /*************************************************************************/
   /*****                                                               *****/
   /*****                      LOOKUP LISTS                             *****/
   /*****                                                               *****/
   /*************************************************************************/
   /*************************************************************************/

   OTL_LOCALDEF( void )
   otl_lookup_validate( OTL_Bytes      table,
                        OTL_Validator  valid )
   {
     OTL_Bytes  p = table;
     OTL_UInt   num_tables;


     if ( table + 6 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     p += 4;
     num_tables = OTL_NEXT_USHORT( p );

     if ( p + num_tables * 2 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     for ( ; num_tables > 0; num_tables-- )
     {
       offset = OTL_NEXT_USHORT( p );

       if ( table + offset >= valid->limit )
         OTL_INVALID_OFFSET;
     }

     /* XXX: check sub-tables? */
   }


   OTL_LOCALDEF( OTL_UInt )
   otl_lookup_get_count( OTL_Bytes  table )
   {
     OTL_Bytes  p = table + 4;


     return OTL_PEEK_USHORT( p );
   }


   OTL_LOCALDEF( OTL_Bytes )
   otl_lookup_get_table( OTL_Bytes  table,
                         OTL_UInt   idx )
   {
     OTL_Bytes  p, result = NULL;
     OTL_UInt   count;


     p     = table + 4;
     count = OTL_NEXT_USHORT( p );
     if ( idx < count )
     {
       p     += idx * 2;
       result = table + OTL_PEEK_USHORT( p );
     }

     return result;
   }


   /*************************************************************************/
   /*************************************************************************/
   /*****                                                               *****/
   /*****                      LOOKUP LISTS                             *****/
   /*****                                                               *****/
   /*************************************************************************/
   /*************************************************************************/

   OTL_LOCALDEF( void )
   otl_lookup_list_validate( OTL_Bytes      table,
                             OTL_Validator  valid )
   {
     OTL_Bytes  p = table, q;
     OTL_UInt   num_lookups, offset;


     if ( p + 2 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     num_lookups = OTL_NEXT_USHORT( p );

     if ( p + num_lookups * 2 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     for ( ; num_lookups > 0; num_lookups-- )
     {
       offset = OTL_NEXT_USHORT( p );

       otl_lookup_validate( table + offset, valid );
     }
   }


   OTL_LOCALDEF( OTL_UInt )
   otl_lookup_list_get_count( OTL_Bytes  table )
   {
     OTL_Bytes  p = table;


     return OTL_PEEK_USHORT( p );
   }


   OTL_LOCALDEF( OTL_Bytes )
   otl_lookup_list_get_lookup( OTL_Bytes  table,
                               OTL_UInt   idx )
   {
     OTL_Bytes  p, result = 0;
     OTL_UInt   count;


     p     = table;
     count = OTL_NEXT_USHORT( p );
     if ( idx < count )
     {
       p     += idx * 2;
       result = table + OTL_PEEK_USHORT( p );
     }

     return result;
   }


   OTL_LOCALDEF( OTL_Bytes )
   otl_lookup_list_get_table( OTL_Bytes  table,
                              OTL_UInt   lookup_index,
                              OTL_UInt   table_index )
   {
     OTL_Bytes  result = NULL;


     result = otl_lookup_list_get_lookup( table, lookup_index );
     if ( result )
       result = otl_lookup_get_table( result, table_index );

     return result;
   }


   OTL_LOCALDEF( void )
   otl_lookup_list_foreach( OTL_Bytes        table,
                            OTL_ForeachFunc  func,
                            OTL_Pointer      func_data )
   {
     OTL_Bytes  p     = table;
     OTL_UInt   count = OTL_NEXT_USHORT( p );


     for ( ; count > 0; count-- )
       func( table + OTL_NEXT_USHORT( p ), func_data );
   }


   /*************************************************************************/
   /*************************************************************************/
   /*****                                                               *****/
   /*****                        FEATURES                               *****/
   /*****                                                               *****/
   /*************************************************************************/
   /*************************************************************************/

   OTL_LOCALDEF( void )
   otl_feature_validate( OTL_Bytes      table,
                         OTL_Validator  valid )
   {
     OTL_Bytes  p = table;
     OTL_UInt   feat_params, num_lookups;


     if ( p + 4 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     feat_params = OTL_NEXT_USHORT( p );  /* ignored */
     num_lookups = OTL_NEXT_USHORT( p );

     if ( p + num_lookups * 2 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     /* XXX: check lookup indices */
   }


   OTL_LOCALDEF( OTL_UInt )
   otl_feature_get_count( OTL_Bytes  table )
   {
     OTL_Bytes  p = table + 4;


     return OTL_PEEK_USHORT( p );
   }


   OTL_LOCALDEF( OTL_UInt )
   otl_feature_get_lookups( OTL_Bytes  table,
                            OTL_UInt   start,
                            OTL_UInt   count,
                            OTL_UInt  *lookups )
   {
     OTL_Bytes  p;
     OTL_UInt   num_features, result = 0;


     p            = table + 4;
     num_features = OTL_NEXT_USHORT( p );

     p += start * 2;

     for ( ; count > 0 && start < num_features; count--, start++ )
     {
       lookups[0] = OTL_NEXT_USHORT(p);
       lookups++;
       result++;
     }

     return result;
   }


   /*************************************************************************/
   /*************************************************************************/
   /*****                                                               *****/
   /*****                        FEATURE LIST                           *****/
   /*****                                                               *****/
   /*************************************************************************/
   /*************************************************************************/

   OTL_LOCALDEF( void )
   otl_feature_list_validate( OTL_Bytes      table,
                              OTL_Validator  valid )
   {
     OTL_Bytes  p = table;
     OTL_UInt   num_features, offset;


     if ( table + 2 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     num_features = OTL_NEXT_USHORT( p );

     if ( p + num_features * 2 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     for ( ; num_features > 0; num_features-- )
     {
       p     += 4;                       /* skip tag */
       offset = OTL_NEXT_USHORT( p );

       otl_feature_table_validate( table + offset, valid );
     }
   }


   OTL_LOCALDEF( OTL_UInt )
   otl_feature_list_get_count( OTL_Bytes  table )
   {
     OTL_Bytes  p = table;


     return OTL_PEEK_USHORT( p );
   }


   OTL_LOCALDEF( OTL_Bytes )
   otl_feature_list_get_feature( OTL_Bytes  table,
                                 OTL_UInt   idx )
   {
     OTL_Bytes  p, result = NULL;
     OTL_UInt   count;


     p     = table;
     count = OTL_NEXT_USHORT( p );

     if ( idx < count )
     {
       p     += idx * 2;
       result = table + OTL_PEEK_USHORT( p );
     }

     return result;
   }


   OTL_LOCALDEF( void )
   otl_feature_list_foreach( OTL_Bytes        table,
                             OTL_ForeachFunc  func,
                             OTL_Pointer      func_data )
   {
     OTL_Bytes  p;
     OTL_UInt   count;


     p = table;
     count = OTL_NEXT_USHORT( p );

     for ( ; count > 0; count-- )
       func( table + OTL_NEXT_USHORT( p ), func_data );
   }


   /*************************************************************************/
   /*************************************************************************/
   /*****                                                               *****/
   /*****                       LANGUAGE SYSTEM                         *****/
   /*****                                                               *****/
   /*************************************************************************/
   /*************************************************************************/


   OTL_LOCALDEF( void )
   otl_lang_validate( OTL_Bytes      table,
                      OTL_Validator  valid )
   {
     OTL_Bytes  p = table;
     OTL_UInt   lookup_order;
     OTL_UInt   req_feature;
     OTL_UInt   num_features;


     if ( table + 6 >= valid->limit )
       OTL_INVALID_TOO_SHORT;

     lookup_order = OTL_NEXT_USHORT( p );
     req_feature  = OTL_NEXT_USHORT( p );
     num_features = OTL_NEXT_USHORT( p );

     /* XXX: check req_feature if not 0xFFFFU */

     if ( p + 2 * num_features >= valid->limit )
       OTL_INVALID_TOO_SHORT;

     /* XXX: check features indices! */
   }


   OTL_LOCALDEF( OTL_UInt )
   otl_lang_get_count( OTL_Bytes  table )
   {
     OTL_Bytes  p = table + 4;

     return OTL_PEEK_USHORT( p );
   }


   OTL_LOCALDEF( OTL_UInt )
   otl_lang_get_req_feature( OTL_Bytes  table )
   {
     OTL_Bytes  p = table + 2;


     return OTL_PEEK_USHORT( p );
   }


   OTL_LOCALDEF( OTL_UInt )
   otl_lang_get_features( OTL_Bytes  table,
                          OTL_UInt   start,
                          OTL_UInt   count,
                          OTL_UInt  *features )
   {
     OTL_Bytes  p            = table + 4;
     OTL_UInt   num_features = OTL_NEXT_USHORT( p );
     OTL_UInt   result       = 0;


     p += start * 2;

     for ( ; count > 0 && start < num_features; start++, count-- )
     {
       features[0] = OTL_NEXT_USHORT( p );
       features++;
       result++;
     }

     return result;
   }


   /*************************************************************************/
   /*************************************************************************/
   /*****                                                               *****/
   /*****                           SCRIPTS                             *****/
   /*****                                                               *****/
   /*************************************************************************/
   /*************************************************************************/


   OTL_LOCALDEF( void )
   otl_script_validate( OTL_Bytes      table,
                        OTL_Validator  valid )
   {
     OTL_UInt   default_lang;
     OTL_Bytes  p = table;


     if ( table + 4 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     default_lang = OTL_NEXT_USHORT( p );
     num_langs    = OTL_NEXT_USHORT( p );

     if ( default_lang != 0 )
     {
       if ( table + default_lang >= valid->limit )
         OTL_INVALID_OFFSET;
     }

     if ( p + num_langs * 6 >= valid->limit )
       OTL_INVALID_OFFSET;

     for ( ; num_langs > 0; num_langs-- )
     {
       OTL_UInt  offset;


       p     += 4;  /* skip tag */
       offset = OTL_NEXT_USHORT( p );

       otl_lang_validate( table + offset, valid );
     }
   }


   OTL_LOCALDEF( void )
   otl_script_list_validate( OTL_Bytes      list,
                             OTL_Validator  valid )
   {
     OTL_UInt   num_scripts;
     OTL_Bytes  p = list;


     if ( list + 2 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     num_scripts = OTL_NEXT_USHORT( p );

     if ( p + num_scripts * 6 > valid->limit )
       OTL_INVALID_TOO_SHORT;

     for ( ; num_scripts > 0; num_scripts-- )
     {
       OTL_UInt  offset;


       p     += 4;                       /* skip tag */
       offset = OTL_NEXT_USHORT( p );

       otl_script_table_validate( list + offset, valid );
     }
   }


   /*************************************************************************/
   /*************************************************************************/
   /*****                                                               *****/
   /*****                         LOOKUP LISTS                          *****/
   /*****                                                               *****/
   /*************************************************************************/
   /*************************************************************************/

   static void
   otl_lookup_table_validate( OTL_Bytes          table,
                              OTL_UInt           type_count,
                              OTL_ValidateFunc*  type_funcs,
                              OTL_Validator      valid )
   {
     OTL_Bytes         p = table;
     OTL_UInt          lookup_type, lookup_flag, count;
     OTL_ValidateFunc  validate;

     OTL_CHECK( 6 );
     lookup_type = OTL_NEXT_USHORT( p );
     lookup_flag = OTL_NEXT_USHORT( p );
     count       = OTL_NEXT_USHORT( p );

     if ( lookup_type == 0 || lookup_type >= type_count )
       OTL_INVALID_DATA;

     validate = type_funcs[ lookup_type - 1 ];

     OTL_CHECK( 2*count );
     for ( ; count > 0; count-- )
       validate( table + OTL_NEXT_USHORT( p ), valid );
   }


   OTL_LOCALDEF( void )
   otl_lookup_list_validate( OTL_Bytes          table,
                             OTL_UInt           type_count,
                             OTL_ValidateFunc*  type_funcs,
                             OTL_Validator      valid )
   {
     OTL_Bytes  p = table;
     OTL_UInt   count;

     OTL_CHECK( 2 );
     count = OTL_NEXT_USHORT( p );

     OTL_CHECK( 2*count );
     for ( ; count > 0; count-- )
       otl_lookup_table_validate( table + OTL_NEXT_USHORT( p ),
                                  type_count, type_funcs, valid );
   }

 /* END */
	/***************************************************************************/
	/* */
	/* otlcommn.c */
	/* */
	/* OpenType layout support, common tables (body). */
	/* */
	/* Copyright 2002 by */
	/* David Turner, Robert Wilhelm, and Werner Lemberg. */
	/* */
	/* This file is part of the FreeType project, and may only be used, */
	/* modified, and distributed under the terms of the FreeType project */
	/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
	/* this file you indicate that you have read the license and */
	/* understand and accept it fully. */
	/* */
	/***************************************************************************/


	#include "otlayout.h"


	/*************************************************************************/
	/*************************************************************************/
	/*** ***/
	/*** COVERAGE TABLE ***/
	/*** ***/
	/*************************************************************************/
	/*************************************************************************/

	OTL_LOCALDEF( void )
	otl_coverage_validate( OTL_Bytes table,
	OTL_Validator valid )
	{
	OTL_Bytes p;
	OTL_UInt format;


	if ( table + 4 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	format = OTL_NEXT_USHORT( p );
	switch ( format )
	{
	case 1:
	{
	OTL_UInt count = OTL_NEXT_USHORT( p );


	if ( p + count * 2 >= valid->limit )
	OTL_INVALID_TOO_SHORT;

	/* XXX: check glyph indices */
	}
	break;

	case 2:
	{
	OTL_UInt n, num_ranges = OTL_NEXT_USHORT( p );
	OTL_UInt start, end, start_cover, total = 0, last = 0;


	if ( p + num_ranges * 6 >= valid->limit )
	OTL_INVALID_TOO_SHORT;

	for ( n = 0; n < num_ranges; n++ )
	{
	start = OTL_NEXT_USHORT( p );
	end = OTL_NEXT_USHORT( p );
	start_cover = OTL_NEXT_USHORT( p );

	if ( start > end \|\| start_cover != total )
	OTL_INVALID_DATA;

	if ( n > 0 && start <= last )
	OTL_INVALID_DATA;

	total += end - start + 1;
	last = end;
	}
	}
	break;

	default:
	OTL_INVALID_FORMAT;
	}
	}


	OTL_LOCALDEF( OTL_UInt )
	otl_coverage_get_count( OTL_Bytes table )
	{
	OTL_Bytes p = table;
	OTL_UInt format = OTL_NEXT_USHORT( p );
	OTL_UInt count = OTL_NEXT_USHORT( p );
	OTL_UInt result = 0;


	switch ( format )
	{
	case 1:
	return count;

	case 2:
	{
	OTL_UInt start, end;


	for ( ; count > 0; count-- )
	{
	start = OTL_NEXT_USHORT( p );
	end = OTL_NEXT_USHORT( p );
	p += 2; /* skip start_index */

	result += end - start + 1;
	}
	}
	break;

	default:
	;
	}

	return result;
	}


	OTL_LOCALDEF( OTL_Int )
	otl_coverage_get_index( OTL_Bytes table,
	OTL_UInt glyph_index )
	{
	OTL_Bytes p = table;
	OTL_UInt format = OTL_NEXT_USHORT( p );
	OTL_UInt count = OTL_NEXT_USHORT( p );


	switch ( format )
	{
	case 1:
	{
	OTL_UInt min = 0, max = count, mid, gindex;


	table += 4;
	while ( min < max )
	{
	mid = ( min + max ) >> 1;
	p = table + 2 * mid;
	gindex = OTL_PEEK_USHORT( p );

	if ( glyph_index == gindex )
	return (OTL_Int)mid;

	if ( glyph_index < gindex )
	max = mid;
	else
	min = mid + 1;
	}
	}
	break;

	case 2:
	{
	OTL_UInt min = 0, max = count, mid;
	OTL_UInt start, end, delta, start_cover;


	table += 4;
	while ( min < max )
	{
	mid = ( min + max ) >> 1;
	p = table + 6 * mid;
	start = OTL_NEXT_USHORT( p );
	end = OTL_NEXT_USHORT( p );

	if ( glyph_index < start )
	max = mid;
	else if ( glyph_index > end )
	min = mid + 1;
	else
	return (OTL_Int)( glyph_index + OTL_NEXT_USHORT( p ) - start );
	}
	}
	break;

	default:
	;
	}

	return -1;
	}


	/*************************************************************************/
	/*************************************************************************/
	/*** ***/
	/*** CLASS DEFINITION TABLE ***/
	/*** ***/
	/*************************************************************************/
	/*************************************************************************/

	OTL_LOCALDEF( void )
	otl_class_definition_validate( OTL_Bytes table,
	OTL_Validator valid )
	{
	OTL_Bytes p = table;
	OTL_UInt format;


	if ( p + 4 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	format = OTL_NEXT_USHORT( p );
	switch ( format )
	{
	case 1:
	{
	OTL_UInt count, start = OTL_NEXT_USHORT( p );


	if ( p + 2 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	count = OTL_NEXT_USHORT( p );

	if ( p + count * 2 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	/* XXX: check glyph indices */
	}
	break;

	case 2:
	{
	OTL_UInt n, num_ranges = OTL_NEXT_USHORT( p );
	OTL_UInt start, end, value, last = 0;


	if ( p + num_ranges * 6 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	for ( n = 0; n < num_ranges; n++ )
	{
	start = OTL_NEXT_USHORT( p );
	end = OTL_NEXT_USHORT( p );
	value = OTL_NEXT_USHORT( p ); /* ignored */

	if ( start > end \|\| ( n > 0 && start <= last ) )
	OTL_INVALID_DATA;

	last = end;
	}
	}
	break;

	default:
	OTL_INVALID_FORMAT;
	}
	}


	OTL_LOCALDEF( OTL_UInt )
	otl_class_definition_get_value( OTL_Bytes table,
	OTL_UInt glyph_index )
	{
	OTL_Bytes p = table;
	OTL_UInt format = OTL_NEXT_USHORT( p );


	switch ( format )
	{
	case 1:
	{
	OTL_UInt start = OTL_NEXT_USHORT( p );
	OTL_UInt count = OTL_NEXT_USHORT( p );
	OTL_UInt idx = (OTL_UInt)( glyph_index - start );


	if ( idx < count )
	{
	p += 2 * idx;
	return OTL_PEEK_USHORT( p );
	}
	}
	break;

	case 2:
	{
	OTL_UInt count = OTL_NEXT_USHORT( p );
	OTL_UInt min = 0, max = count, mid, gindex;


	table += 4;
	while ( min < max )
	{
	mid = ( min + max ) >> 1;
	p = table + 6 * mid;
	start = OTL_NEXT_USHORT( p );
	end = OTL_NEXT_USHORT( p );

	if ( glyph_index < start )
	max = mid;
	else if ( glyph_index > end )
	min = mid + 1;
	else
	return OTL_PEEK_USHORT( p );
	}
	}
	break;

	default:
	;
	}

	return 0;
	}


	/*************************************************************************/
	/*************************************************************************/
	/*** ***/
	/*** DEVICE TABLE ***/
	/*** ***/
	/*************************************************************************/
	/*************************************************************************/

	OTL_LOCALDEF( void )
	otl_device_table_validate( OTL_Bytes table,
	OTL_Validator valid )
	{
	OTL_Bytes p = table;
	OTL_UInt start, end, count, format, count;


	if ( p + 8 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	start = OTL_NEXT_USHORT( p );
	end = OTL_NEXT_USHORT( p );
	format = OTL_NEXT_USHORT( p );

	if ( format < 1 \|\| format > 3 \|\| end < start )
	OTL_INVALID_DATA;

	count = (OTL_UInt)( end - start + 1 );

	if ( p + ( ( 1 << format ) * count ) / 8 > valid->limit )
	OTL_INVALID_TOO_SHORT;
	}


	OTL_LOCALDEF( OTL_UInt )
	otl_device_table_get_start( OTL_Bytes table )
	{
	OTL_Bytes p = table;


	return OTL_PEEK_USHORT( p );
	}


	OTL_LOCALDEF( OTL_UInt )
	otl_device_table_get_end( OTL_Bytes table )
	{
	OTL_Bytes p = table + 2;


	return OTL_PEEK_USHORT( p );
	}


	OTL_LOCALDEF( OTL_Int )
	otl_device_table_get_delta( OTL_Bytes table,
	OTL_UInt size )
	{
	OTL_Bytes p = table;
	OTL_Int result = 0;
	OTL_UInt start, end, format, idx, value;


	start = OTL_NEXT_USHORT( p );
	end = OTL_NEXT_USHORT( p );
	format = OTL_NEXT_USHORT( p );

	if ( size >= start && size <= end )
	{
	/* we could do that with clever bit operations, but a switch is */
	/* much simpler to understand and maintain */
	/* */
	switch ( format )
	{
	case 1:
	idx = (OTL_UInt)( ( size - start ) * 2 );
	p += idx / 16;
	value = OTL_PEEK_USHORT( p );
	shift = idx & 15;
	result = (OTL_Short)( value << shift ) >> ( 14 - shift );

	break;

	case 2:
	idx = (OTL_UInt)( ( size - start ) * 4 );
	p += idx / 16;
	value = OTL_PEEK_USHORT( p );
	shift = idx & 15;
	result = (OTL_Short)( value << shift ) >> ( 12 - shift );

	break;

	case 3:
	idx = (OTL_UInt)( ( size - start ) * 8 );
	p += idx / 16;
	value = OTL_PEEK_USHORT( p );
	shift = idx & 15;
	result = (OTL_Short)( value << shift ) >> ( 8 - shift );

	break;

	default:
	;
	}
	}

	return result;
	}


	/*************************************************************************/
	/*************************************************************************/
	/*** ***/
	/*** LOOKUP LISTS ***/
	/*** ***/
	/*************************************************************************/
	/*************************************************************************/

	OTL_LOCALDEF( void )
	otl_lookup_validate( OTL_Bytes table,
	OTL_Validator valid )
	{
	OTL_Bytes p = table;
	OTL_UInt num_tables;


	if ( table + 6 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	p += 4;
	num_tables = OTL_NEXT_USHORT( p );

	if ( p + num_tables * 2 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	for ( ; num_tables > 0; num_tables-- )
	{
	offset = OTL_NEXT_USHORT( p );

	if ( table + offset >= valid->limit )
	OTL_INVALID_OFFSET;
	}

	/* XXX: check sub-tables? */
	}


	OTL_LOCALDEF( OTL_UInt )
	otl_lookup_get_count( OTL_Bytes table )
	{
	OTL_Bytes p = table + 4;


	return OTL_PEEK_USHORT( p );
	}


	OTL_LOCALDEF( OTL_Bytes )
	otl_lookup_get_table( OTL_Bytes table,
	OTL_UInt idx )
	{
	OTL_Bytes p, result = NULL;
	OTL_UInt count;


	p = table + 4;
	count = OTL_NEXT_USHORT( p );
	if ( idx < count )
	{
	p += idx * 2;
	result = table + OTL_PEEK_USHORT( p );
	}

	return result;
	}


	/*************************************************************************/
	/*************************************************************************/
	/*** ***/
	/*** LOOKUP LISTS ***/
	/*** ***/
	/*************************************************************************/
	/*************************************************************************/

	OTL_LOCALDEF( void )
	otl_lookup_list_validate( OTL_Bytes table,
	OTL_Validator valid )
	{
	OTL_Bytes p = table, q;
	OTL_UInt num_lookups, offset;


	if ( p + 2 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	num_lookups = OTL_NEXT_USHORT( p );

	if ( p + num_lookups * 2 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	for ( ; num_lookups > 0; num_lookups-- )
	{
	offset = OTL_NEXT_USHORT( p );

	otl_lookup_validate( table + offset, valid );
	}
	}


	OTL_LOCALDEF( OTL_UInt )
	otl_lookup_list_get_count( OTL_Bytes table )
	{
	OTL_Bytes p = table;


	return OTL_PEEK_USHORT( p );
	}


	OTL_LOCALDEF( OTL_Bytes )
	otl_lookup_list_get_lookup( OTL_Bytes table,
	OTL_UInt idx )
	{
	OTL_Bytes p, result = 0;
	OTL_UInt count;


	p = table;
	count = OTL_NEXT_USHORT( p );
	if ( idx < count )
	{
	p += idx * 2;
	result = table + OTL_PEEK_USHORT( p );
	}

	return result;
	}


	OTL_LOCALDEF( OTL_Bytes )
	otl_lookup_list_get_table( OTL_Bytes table,
	OTL_UInt lookup_index,
	OTL_UInt table_index )
	{
	OTL_Bytes result = NULL;


	result = otl_lookup_list_get_lookup( table, lookup_index );
	if ( result )
	result = otl_lookup_get_table( result, table_index );

	return result;
	}


	OTL_LOCALDEF( void )
	otl_lookup_list_foreach( OTL_Bytes table,
	OTL_ForeachFunc func,
	OTL_Pointer func_data )
	{
	OTL_Bytes p = table;
	OTL_UInt count = OTL_NEXT_USHORT( p );


	for ( ; count > 0; count-- )
	func( table + OTL_NEXT_USHORT( p ), func_data );
	}


	/*************************************************************************/
	/*************************************************************************/
	/*** ***/
	/*** FEATURES ***/
	/*** ***/
	/*************************************************************************/
	/*************************************************************************/

	OTL_LOCALDEF( void )
	otl_feature_validate( OTL_Bytes table,
	OTL_Validator valid )
	{
	OTL_Bytes p = table;
	OTL_UInt feat_params, num_lookups;


	if ( p + 4 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	feat_params = OTL_NEXT_USHORT( p ); /* ignored */
	num_lookups = OTL_NEXT_USHORT( p );

	if ( p + num_lookups * 2 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	/* XXX: check lookup indices */
	}


	OTL_LOCALDEF( OTL_UInt )
	otl_feature_get_count( OTL_Bytes table )
	{
	OTL_Bytes p = table + 4;


	return OTL_PEEK_USHORT( p );
	}


	OTL_LOCALDEF( OTL_UInt )
	otl_feature_get_lookups( OTL_Bytes table,
	OTL_UInt start,
	OTL_UInt count,
	OTL_UInt *lookups )
	{
	OTL_Bytes p;
	OTL_UInt num_features, result = 0;


	p = table + 4;
	num_features = OTL_NEXT_USHORT( p );

	p += start * 2;

	for ( ; count > 0 && start < num_features; count--, start++ )
	{
	lookups[0] = OTL_NEXT_USHORT(p);
	lookups++;
	result++;
	}

	return result;
	}


	/*************************************************************************/
	/*************************************************************************/
	/*** ***/
	/*** FEATURE LIST ***/
	/*** ***/
	/*************************************************************************/
	/*************************************************************************/

	OTL_LOCALDEF( void )
	otl_feature_list_validate( OTL_Bytes table,
	OTL_Validator valid )
	{
	OTL_Bytes p = table;
	OTL_UInt num_features, offset;


	if ( table + 2 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	num_features = OTL_NEXT_USHORT( p );

	if ( p + num_features * 2 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	for ( ; num_features > 0; num_features-- )
	{
	p += 4; /* skip tag */
	offset = OTL_NEXT_USHORT( p );

	otl_feature_table_validate( table + offset, valid );
	}
	}


	OTL_LOCALDEF( OTL_UInt )
	otl_feature_list_get_count( OTL_Bytes table )
	{
	OTL_Bytes p = table;


	return OTL_PEEK_USHORT( p );
	}


	OTL_LOCALDEF( OTL_Bytes )
	otl_feature_list_get_feature( OTL_Bytes table,
	OTL_UInt idx )
	{
	OTL_Bytes p, result = NULL;
	OTL_UInt count;


	p = table;
	count = OTL_NEXT_USHORT( p );

	if ( idx < count )
	{
	p += idx * 2;
	result = table + OTL_PEEK_USHORT( p );
	}

	return result;
	}


	OTL_LOCALDEF( void )
	otl_feature_list_foreach( OTL_Bytes table,
	OTL_ForeachFunc func,
	OTL_Pointer func_data )
	{
	OTL_Bytes p;
	OTL_UInt count;


	p = table;
	count = OTL_NEXT_USHORT( p );

	for ( ; count > 0; count-- )
	func( table + OTL_NEXT_USHORT( p ), func_data );
	}


	/*************************************************************************/
	/*************************************************************************/
	/*** ***/
	/*** LANGUAGE SYSTEM ***/
	/*** ***/
	/*************************************************************************/
	/*************************************************************************/


	OTL_LOCALDEF( void )
	otl_lang_validate( OTL_Bytes table,
	OTL_Validator valid )
	{
	OTL_Bytes p = table;
	OTL_UInt lookup_order;
	OTL_UInt req_feature;
	OTL_UInt num_features;


	if ( table + 6 >= valid->limit )
	OTL_INVALID_TOO_SHORT;

	lookup_order = OTL_NEXT_USHORT( p );
	req_feature = OTL_NEXT_USHORT( p );
	num_features = OTL_NEXT_USHORT( p );

	/* XXX: check req_feature if not 0xFFFFU */

	if ( p + 2 * num_features >= valid->limit )
	OTL_INVALID_TOO_SHORT;

	/* XXX: check features indices! */
	}


	OTL_LOCALDEF( OTL_UInt )
	otl_lang_get_count( OTL_Bytes table )
	{
	OTL_Bytes p = table + 4;

	return OTL_PEEK_USHORT( p );
	}


	OTL_LOCALDEF( OTL_UInt )
	otl_lang_get_req_feature( OTL_Bytes table )
	{
	OTL_Bytes p = table + 2;


	return OTL_PEEK_USHORT( p );
	}


	OTL_LOCALDEF( OTL_UInt )
	otl_lang_get_features( OTL_Bytes table,
	OTL_UInt start,
	OTL_UInt count,
	OTL_UInt *features )
	{
	OTL_Bytes p = table + 4;
	OTL_UInt num_features = OTL_NEXT_USHORT( p );
	OTL_UInt result = 0;


	p += start * 2;

	for ( ; count > 0 && start < num_features; start++, count-- )
	{
	features[0] = OTL_NEXT_USHORT( p );
	features++;
	result++;
	}

	return result;
	}




	/*************************************************************************/
	/*************************************************************************/
	/*** ***/
	/*** SCRIPTS ***/
	/*** ***/
	/*************************************************************************/
	/*************************************************************************/


	OTL_LOCALDEF( void )
	otl_script_validate( OTL_Bytes table,
	OTL_Validator valid )
	{
	OTL_UInt default_lang;
	OTL_Bytes p = table;


	if ( table + 4 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	default_lang = OTL_NEXT_USHORT( p );
	num_langs = OTL_NEXT_USHORT( p );

	if ( default_lang != 0 )
	{
	if ( table + default_lang >= valid->limit )
	OTL_INVALID_OFFSET;
	}

	if ( p + num_langs * 6 >= valid->limit )
	OTL_INVALID_OFFSET;

	for ( ; num_langs > 0; num_langs-- )
	{
	OTL_UInt offset;


	p += 4; /* skip tag */
	offset = OTL_NEXT_USHORT( p );

	otl_lang_validate( table + offset, valid );
	}
	}


	OTL_LOCALDEF( void )
	otl_script_list_validate( OTL_Bytes list,
	OTL_Validator valid )
	{
	OTL_UInt num_scripts;
	OTL_Bytes p = list;


	if ( list + 2 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	num_scripts = OTL_NEXT_USHORT( p );

	if ( p + num_scripts * 6 > valid->limit )
	OTL_INVALID_TOO_SHORT;

	for ( ; num_scripts > 0; num_scripts-- )
	{
	OTL_UInt offset;


	p += 4; /* skip tag */
	offset = OTL_NEXT_USHORT( p );

	otl_script_table_validate( list + offset, valid );
	}
	}


	/*************************************************************************/
	/*************************************************************************/
	/*** ***/
	/*** LOOKUP LISTS ***/
	/*** ***/
	/*************************************************************************/
	/*************************************************************************/

	static void
	otl_lookup_table_validate( OTL_Bytes table,
	OTL_UInt type_count,
	OTL_ValidateFunc* type_funcs,
	OTL_Validator valid )
	{
	OTL_Bytes p = table;
	OTL_UInt lookup_type, lookup_flag, count;
	OTL_ValidateFunc validate;

	OTL_CHECK( 6 );
	lookup_type = OTL_NEXT_USHORT( p );
	lookup_flag = OTL_NEXT_USHORT( p );
	count = OTL_NEXT_USHORT( p );

	if ( lookup_type == 0 \|\| lookup_type >= type_count )
	OTL_INVALID_DATA;

	validate = type_funcs[ lookup_type - 1 ];

	OTL_CHECK( 2*count );
	for ( ; count > 0; count-- )
	validate( table + OTL_NEXT_USHORT( p ), valid );
	}


	OTL_LOCALDEF( void )
	otl_lookup_list_validate( OTL_Bytes table,
	OTL_UInt type_count,
	OTL_ValidateFunc* type_funcs,
	OTL_Validator valid )
	{
	OTL_Bytes p = table;
	OTL_UInt count;

	OTL_CHECK( 2 );
	count = OTL_NEXT_USHORT( p );

	OTL_CHECK( 2*count );
	for ( ; count > 0; count-- )
	otl_lookup_table_validate( table + OTL_NEXT_USHORT( p ),
	type_count, type_funcs, valid );
	}

	/* END */