/***************************************************************************/
/*                                                                         */
/*  cffgload.c                                                             */
/*                                                                         */
/*    OpenType Glyph Loader (body).                                        */
/*                                                                         */
/*  Copyright 1996-2012 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 <ft2build.h>
#include FT_INTERNAL_DEBUG_H
#include FT_INTERNAL_STREAM_H
#include FT_INTERNAL_SFNT_H
#include FT_OUTLINE_H

#include "cffobjs.h"
#include "cffload.h"
#include "cffgload.h"

#include "cfferrs.h"


  /*************************************************************************/
  /*                                                                       */
  /* The macro FT_COMPONENT is used in trace mode.  It is an implicit      */
  /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log  */
  /* messages during execution.                                            */
  /*                                                                       */
#undef  FT_COMPONENT
#define FT_COMPONENT  trace_cffgload


  typedef enum  CFF_Operator_
  {
    cff_op_unknown = 0,

    cff_op_rmoveto,
    cff_op_hmoveto,
    cff_op_vmoveto,

    cff_op_rlineto,
    cff_op_hlineto,
    cff_op_vlineto,

    cff_op_rrcurveto,
    cff_op_hhcurveto,
    cff_op_hvcurveto,
    cff_op_rcurveline,
    cff_op_rlinecurve,
    cff_op_vhcurveto,
    cff_op_vvcurveto,

    cff_op_flex,
    cff_op_hflex,
    cff_op_hflex1,
    cff_op_flex1,

    cff_op_endchar,

    cff_op_hstem,
    cff_op_vstem,
    cff_op_hstemhm,
    cff_op_vstemhm,

    cff_op_hintmask,
    cff_op_cntrmask,
    cff_op_dotsection,  /* deprecated, acts as no-op */

    cff_op_abs,
    cff_op_add,
    cff_op_sub,
    cff_op_div,
    cff_op_neg,
    cff_op_random,
    cff_op_mul,
    cff_op_sqrt,

    cff_op_blend,

    cff_op_drop,
    cff_op_exch,
    cff_op_index,
    cff_op_roll,
    cff_op_dup,

    cff_op_put,
    cff_op_get,
    cff_op_store,
    cff_op_load,

    cff_op_and,
    cff_op_or,
    cff_op_not,
    cff_op_eq,
    cff_op_ifelse,

    cff_op_callsubr,
    cff_op_callgsubr,
    cff_op_return,

    /* Type 1 opcodes: invalid but seen in real life */
    cff_op_hsbw,
    cff_op_closepath,
    cff_op_callothersubr,
    cff_op_pop,
    cff_op_seac,
    cff_op_sbw,
    cff_op_setcurrentpoint,

    /* do not remove */
    cff_op_max

  } CFF_Operator;


#define CFF_COUNT_CHECK_WIDTH  0x80
#define CFF_COUNT_EXACT        0x40
#define CFF_COUNT_CLEAR_STACK  0x20

  /* count values which have the `CFF_COUNT_CHECK_WIDTH' flag set are  */
  /* used for checking the width and requested numbers of arguments    */
  /* only; they are set to zero afterwards                             */

  /* the other two flags are informative only and unused currently     */

  static const FT_Byte  cff_argument_counts[] =
  {
    0,  /* unknown */

    2 | CFF_COUNT_CHECK_WIDTH | CFF_COUNT_EXACT, /* rmoveto */
    1 | CFF_COUNT_CHECK_WIDTH | CFF_COUNT_EXACT,
    1 | CFF_COUNT_CHECK_WIDTH | CFF_COUNT_EXACT,

    0 | CFF_COUNT_CLEAR_STACK, /* rlineto */
    0 | CFF_COUNT_CLEAR_STACK,
    0 | CFF_COUNT_CLEAR_STACK,

    0 | CFF_COUNT_CLEAR_STACK, /* rrcurveto */
    0 | CFF_COUNT_CLEAR_STACK,
    0 | CFF_COUNT_CLEAR_STACK,
    0 | CFF_COUNT_CLEAR_STACK,
    0 | CFF_COUNT_CLEAR_STACK,
    0 | CFF_COUNT_CLEAR_STACK,
    0 | CFF_COUNT_CLEAR_STACK,

    13, /* flex */
    7,
    9,
    11,

    0 | CFF_COUNT_CHECK_WIDTH, /* endchar */

    2 | CFF_COUNT_CHECK_WIDTH, /* hstem */
    2 | CFF_COUNT_CHECK_WIDTH,
    2 | CFF_COUNT_CHECK_WIDTH,
    2 | CFF_COUNT_CHECK_WIDTH,

    0 | CFF_COUNT_CHECK_WIDTH, /* hintmask */
    0 | CFF_COUNT_CHECK_WIDTH, /* cntrmask */
    0, /* dotsection */

    1, /* abs */
    2,
    2,
    2,
    1,
    0,
    2,
    1,

    1, /* blend */

    1, /* drop */
    2,
    1,
    2,
    1,

    2, /* put */
    1,
    4,
    3,

    2, /* and */
    2,
    1,
    2,
    4,

    1, /* callsubr */
    1,
    0,

    2, /* hsbw */
    0,
    0,
    0,
    5, /* seac */
    4, /* sbw */
    2  /* setcurrentpoint */
  };


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /**********                                                      *********/
  /**********                                                      *********/
  /**********             GENERIC CHARSTRING PARSING               *********/
  /**********                                                      *********/
  /**********                                                      *********/
  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    cff_builder_init                                                   */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Initializes a given glyph builder.                                 */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    builder :: A pointer to the glyph builder to initialize.           */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face    :: The current face object.                                */
  /*                                                                       */
  /*    size    :: The current size object.                                */
  /*                                                                       */
  /*    glyph   :: The current glyph object.                               */
  /*                                                                       */
  /*    hinting :: Whether hinting is active.                              */
  /*                                                                       */
  static void
  cff_builder_init( CFF_Builder*   builder,
                    TT_Face        face,
                    CFF_Size       size,
                    CFF_GlyphSlot  glyph,
                    FT_Bool        hinting )
  {
    builder->path_begun  = 0;
    builder->load_points = 1;

    builder->face   = face;
    builder->glyph  = glyph;
    builder->memory = face->root.memory;

    if ( glyph )
    {
      FT_GlyphLoader  loader = glyph->root.internal->loader;


      builder->loader  = loader;
      builder->base    = &loader->base.outline;
      builder->current = &loader->current.outline;
      FT_GlyphLoader_Rewind( loader );

      builder->hints_globals = 0;
      builder->hints_funcs   = 0;

      if ( hinting && size )
      {
        CFF_Internal  internal = (CFF_Internal)size->root.internal;


        builder->hints_globals = (void *)internal->topfont;
        builder->hints_funcs   = glyph->root.internal->glyph_hints;
      }
    }

    builder->pos_x = 0;
    builder->pos_y = 0;

    builder->left_bearing.x = 0;
    builder->left_bearing.y = 0;
    builder->advance.x      = 0;
    builder->advance.y      = 0;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    cff_builder_done                                                   */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Finalizes a given glyph builder.  Its contents can still be used   */
  /*    after the call, but the function saves important information       */
  /*    within the corresponding glyph slot.                               */
  /*                                                                       */
  /* <Input>                                                               */
  /*    builder :: A pointer to the glyph builder to finalize.             */
  /*                                                                       */
  static void
  cff_builder_done( CFF_Builder*  builder )
  {
    CFF_GlyphSlot  glyph = builder->glyph;


    if ( glyph )
      glyph->root.outline = *builder->base;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    cff_compute_bias                                                   */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Computes the bias value in dependence of the number of glyph       */
  /*    subroutines.                                                       */
  /*                                                                       */
  /* <Input>                                                               */
  /*    in_charstring_type :: The `CharstringType' value of the top DICT   */
  /*                          dictionary.                                  */
  /*                                                                       */
  /*    num_subrs          :: The number of glyph subroutines.             */
  /*                                                                       */
  /* <Return>                                                              */
  /*    The bias value.                                                    */
  static FT_Int
  cff_compute_bias( FT_Int   in_charstring_type,
                    FT_UInt  num_subrs )
  {
    FT_Int  result;


    if ( in_charstring_type == 1 )
      result = 0;
    else if ( num_subrs < 1240 )
      result = 107;
    else if ( num_subrs < 33900U )
      result = 1131;
    else
      result = 32768U;

    return result;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    cff_decoder_init                                                   */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Initializes a given glyph decoder.                                 */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    decoder :: A pointer to the glyph builder to initialize.           */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face      :: The current face object.                              */
  /*                                                                       */
  /*    size      :: The current size object.                              */
  /*                                                                       */
  /*    slot      :: The current glyph object.                             */
  /*                                                                       */
  /*    hinting   :: Whether hinting is active.                            */
  /*                                                                       */
  /*    hint_mode :: The hinting mode.                                     */
  /*                                                                       */
  FT_LOCAL_DEF( void )
  cff_decoder_init( CFF_Decoder*    decoder,
                    TT_Face         face,
                    CFF_Size        size,
                    CFF_GlyphSlot   slot,
                    FT_Bool         hinting,
                    FT_Render_Mode  hint_mode )
  {
    CFF_Font  cff = (CFF_Font)face->extra.data;


    /* clear everything */
    FT_MEM_ZERO( decoder, sizeof ( *decoder ) );

    /* initialize builder */
    cff_builder_init( &decoder->builder, face, size, slot, hinting );

    /* initialize Type2 decoder */
    decoder->cff          = cff;
    decoder->num_globals  = cff->global_subrs_index.count;
    decoder->globals      = cff->global_subrs;
    decoder->globals_bias = cff_compute_bias(
                              cff->top_font.font_dict.charstring_type,
                              decoder->num_globals );

    decoder->hint_mode    = hint_mode;
  }


  /* this function is used to select the subfont */
  /* and the locals subrs array                  */
  FT_LOCAL_DEF( FT_Error )
  cff_decoder_prepare( CFF_Decoder*  decoder,
                       CFF_Size      size,
                       FT_UInt       glyph_index )
  {
    CFF_Builder  *builder = &decoder->builder;
    CFF_Font      cff     = (CFF_Font)builder->face->extra.data;
    CFF_SubFont   sub     = &cff->top_font;
    FT_Error      error   = CFF_Err_Ok;


    /* manage CID fonts */
    if ( cff->num_subfonts )
    {
      FT_Byte  fd_index = cff_fd_select_get( &cff->fd_select, glyph_index );


      if ( fd_index >= cff->num_subfonts )
      {
        FT_TRACE4(( "cff_decoder_prepare: invalid CID subfont index\n" ));
        error = CFF_Err_Invalid_File_Format;
        goto Exit;
      }

      FT_TRACE3(( "glyph index %d (subfont %d):\n", glyph_index, fd_index ));

      sub = cff->subfonts[fd_index];

      if ( builder->hints_funcs && size )
      {
        CFF_Internal  internal = (CFF_Internal)size->root.internal;


        /* for CFFs without subfonts, this value has already been set */
        builder->hints_globals = (void *)internal->subfonts[fd_index];
      }
    }
#ifdef FT_DEBUG_LEVEL_TRACE
    else
      FT_TRACE3(( "glyph index %d:\n", glyph_index ));
#endif

    decoder->num_locals    = sub->local_subrs_index.count;
    decoder->locals        = sub->local_subrs;
    decoder->locals_bias   = cff_compute_bias(
                               decoder->cff->top_font.font_dict.charstring_type,
                               decoder->num_locals );

    decoder->glyph_width   = sub->private_dict.default_width;
    decoder->nominal_width = sub->private_dict.nominal_width;

  Exit:
    return error;
  }


  /* check that there is enough space for `count' more points */
  static FT_Error
  check_points( CFF_Builder*  builder,
                FT_Int        count )
  {
    return FT_GLYPHLOADER_CHECK_POINTS( builder->loader, count, 0 );
  }


  /* add a new point, do not check space */
  static void
  cff_builder_add_point( CFF_Builder*  builder,
                         FT_Pos        x,
                         FT_Pos        y,
                         FT_Byte       flag )
  {
    FT_Outline*  outline = builder->current;


    if ( builder->load_points )
    {
      FT_Vector*  point   = outline->points + outline->n_points;
      FT_Byte*    control = (FT_Byte*)outline->tags + outline->n_points;


      point->x = x >> 16;
      point->y = y >> 16;
      *control = (FT_Byte)( flag ? FT_CURVE_TAG_ON : FT_CURVE_TAG_CUBIC );
    }

    outline->n_points++;
  }


  /* check space for a new on-curve point, then add it */
  static FT_Error
  cff_builder_add_point1( CFF_Builder*  builder,
                          FT_Pos        x,
                          FT_Pos        y )
  {
    FT_Error  error;


    error = check_points( builder, 1 );
    if ( !error )
      cff_builder_add_point( builder, x, y, 1 );

    return error;
  }


  /* check space for a new contour, then add it */
  static FT_Error
  cff_builder_add_contour( CFF_Builder*  builder )
  {
    FT_Outline*  outline = builder->current;
    FT_Error     error;


    if ( !builder->load_points )
    {
      outline->n_contours++;
      return CFF_Err_Ok;
    }

    error = FT_GLYPHLOADER_CHECK_POINTS( builder->loader, 0, 1 );
    if ( !error )
    {
      if ( outline->n_contours > 0 )
        outline->contours[outline->n_contours - 1] =
          (short)( outline->n_points - 1 );

      outline->n_contours++;
    }

    return error;
  }


  /* if a path was begun, add its first on-curve point */
  static FT_Error
  cff_builder_start_point( CFF_Builder*  builder,
                           FT_Pos        x,
                           FT_Pos        y )
  {
    FT_Error  error = CFF_Err_Ok;


    /* test whether we are building a new contour */
    if ( !builder->path_begun )
    {
      builder->path_begun = 1;
      error = cff_builder_add_contour( builder );
      if ( !error )
        error = cff_builder_add_point1( builder, x, y );
    }

    return error;
  }


  /* close the current contour */
  static void
  cff_builder_close_contour( CFF_Builder*  builder )
  {
    FT_Outline*  outline = builder->current;
    FT_Int       first;


    if ( !outline )
      return;

    first = outline->n_contours <= 1
            ? 0 : outline->contours[outline->n_contours - 2] + 1;

    /* We must not include the last point in the path if it */
    /* is located on the first point.                       */
    if ( outline->n_points > 1 )
    {
      FT_Vector*  p1      = outline->points + first;
      FT_Vector*  p2      = outline->points + outline->n_points - 1;
      FT_Byte*    control = (FT_Byte*)outline->tags + outline->n_points - 1;


      /* `delete' last point only if it coincides with the first    */
      /* point and if it is not a control point (which can happen). */
      if ( p1->x == p2->x && p1->y == p2->y )
        if ( *control == FT_CURVE_TAG_ON )
          outline->n_points--;
    }

    if ( outline->n_contours > 0 )
    {
      /* Don't add contours only consisting of one point, i.e., */
      /* check whether begin point and last point are the same. */
      if ( first == outline->n_points - 1 )
      {
        outline->n_contours--;
        outline->n_points--;
      }
      else
        outline->contours[outline->n_contours - 1] =
          (short)( outline->n_points - 1 );
    }
  }


  static FT_Int
  cff_lookup_glyph_by_stdcharcode( CFF_Font  cff,
                                   FT_Int    charcode )
  {
    FT_UInt    n;
    FT_UShort  glyph_sid;


    /* CID-keyed fonts don't have glyph names */
    if ( !cff->charset.sids )
      return -1;

    /* check range of standard char code */
    if ( charcode < 0 || charcode > 255 )
      return -1;

    /* Get code to SID mapping from `cff_standard_encoding'. */
    glyph_sid = cff_get_standard_encoding( (FT_UInt)charcode );

    for ( n = 0; n < cff->num_glyphs; n++ )
    {
      if ( cff->charset.sids[n] == glyph_sid )
        return n;
    }

    return -1;
  }


  static FT_Error
  cff_get_glyph_data( TT_Face    face,
                      FT_UInt    glyph_index,
                      FT_Byte**  pointer,
                      FT_ULong*  length )
  {
#ifdef FT_CONFIG_OPTION_INCREMENTAL
    /* For incremental fonts get the character data using the */
    /* callback function.                                     */
    if ( face->root.internal->incremental_interface )
    {
      FT_Data   data;
      FT_Error  error =
                  face->root.internal->incremental_interface->funcs->get_glyph_data(
                    face->root.internal->incremental_interface->object,
                    glyph_index, &data );


      *pointer = (FT_Byte*)data.pointer;
      *length = data.length;

      return error;
    }
    else
#endif /* FT_CONFIG_OPTION_INCREMENTAL */

    {
      CFF_Font  cff  = (CFF_Font)(face->extra.data);


      return cff_index_access_element( &cff->charstrings_index, glyph_index,
                                       pointer, length );
    }
  }


  static void
  cff_free_glyph_data( TT_Face    face,
                       FT_Byte**  pointer,
                       FT_ULong   length )
  {
#ifndef FT_CONFIG_OPTION_INCREMENTAL
    FT_UNUSED( length );
#endif

#ifdef FT_CONFIG_OPTION_INCREMENTAL
    /* For incremental fonts get the character data using the */
    /* callback function.                                     */
    if ( face->root.internal->incremental_interface )
    {
      FT_Data data;


      data.pointer = *pointer;
      data.length  = length;

      face->root.internal->incremental_interface->funcs->free_glyph_data(
        face->root.internal->incremental_interface->object, &data );
    }
    else
#endif /* FT_CONFIG_OPTION_INCREMENTAL */

    {
      CFF_Font  cff = (CFF_Font)(face->extra.data);


      cff_index_forget_element( &cff->charstrings_index, pointer );
    }
  }


  static FT_Error
  cff_operator_seac( CFF_Decoder*  decoder,
                     FT_Pos        asb,
                     FT_Pos        adx,
                     FT_Pos        ady,
                     FT_Int        bchar,
                     FT_Int        achar )
  {
    FT_Error      error;
    CFF_Builder*  builder = &decoder->builder;
    FT_Int        bchar_index, achar_index;
    TT_Face       face = decoder->builder.face;
    FT_Vector     left_bearing, advance;
    FT_Byte*      charstring;
    FT_ULong      charstring_len;
    FT_Pos        glyph_width;


    if ( decoder->seac )
    {
      FT_ERROR(( "cff_operator_seac: invalid nested seac\n" ));
      return CFF_Err_Syntax_Error;
    }

    adx += decoder->builder.left_bearing.x;
    ady += decoder->builder.left_bearing.y;

#ifdef FT_CONFIG_OPTION_INCREMENTAL
    /* Incremental fonts don't necessarily have valid charsets.        */
    /* They use the character code, not the glyph index, in this case. */
    if ( face->root.internal->incremental_interface )
    {
      bchar_index = bchar;
      achar_index = achar;
    }
    else
#endif /* FT_CONFIG_OPTION_INCREMENTAL */
    {
      CFF_Font cff = (CFF_Font)(face->extra.data);


      bchar_index = cff_lookup_glyph_by_stdcharcode( cff, bchar );
      achar_index = cff_lookup_glyph_by_stdcharcode( cff, achar );
    }

    if ( bchar_index < 0 || achar_index < 0 )
    {
      FT_ERROR(( "cff_operator_seac:"
                 " invalid seac character code arguments\n" ));
      return CFF_Err_Syntax_Error;
    }

    /* If we are trying to load a composite glyph, do not load the */
    /* accent character and return the array of subglyphs.         */
    if ( builder->no_recurse )
    {
      FT_GlyphSlot    glyph  = (FT_GlyphSlot)builder->glyph;
      FT_GlyphLoader  loader = glyph->internal->loader;
      FT_SubGlyph     subg;


      /* reallocate subglyph array if necessary */
      error = FT_GlyphLoader_CheckSubGlyphs( loader, 2 );
      if ( error )
        goto Exit;

      subg = loader->current.subglyphs;

      /* subglyph 0 = base character */
      subg->index = bchar_index;
      subg->flags = FT_SUBGLYPH_FLAG_ARGS_ARE_XY_VALUES |
                    FT_SUBGLYPH_FLAG_USE_MY_METRICS;
      subg->arg1  = 0;
      subg->arg2  = 0;
      subg++;

      /* subglyph 1 = accent character */
      subg->index = achar_index;
      subg->flags = FT_SUBGLYPH_FLAG_ARGS_ARE_XY_VALUES;
      subg->arg1  = (FT_Int)( adx >> 16 );
      subg->arg2  = (FT_Int)( ady >> 16 );

      /* set up remaining glyph fields */
      glyph->num_subglyphs = 2;
      glyph->subglyphs     = loader->base.subglyphs;
      glyph->format        = FT_GLYPH_FORMAT_COMPOSITE;

      loader->current.num_subglyphs = 2;
    }

    FT_GlyphLoader_Prepare( builder->loader );

    /* First load `bchar' in builder */
    error = cff_get_glyph_data( face, bchar_index,
                                &charstring, &charstring_len );
    if ( !error )
    {
      /* the seac operator must not be nested */
      decoder->seac = TRUE;
      error = cff_decoder_parse_charstrings( decoder, charstring,
                                             charstring_len );
      decoder->seac = FALSE;

      cff_free_glyph_data( face, &charstring, charstring_len );

      if ( error )
        goto Exit;
    }

    /* Save the left bearing, advance and glyph width of the base */
    /* character as they will be erased by the next load.         */

    left_bearing = builder->left_bearing;
    advance      = builder->advance;
    glyph_width  = decoder->glyph_width;

    builder->left_bearing.x = 0;
    builder->left_bearing.y = 0;

    builder->pos_x = adx - asb;
    builder->pos_y = ady;

    /* Now load `achar' on top of the base outline. */
    error = cff_get_glyph_data( face, achar_index,
                                &charstring, &charstring_len );
    if ( !error )
    {
      /* the seac operator must not be nested */
      decoder->seac = TRUE;
      error = cff_decoder_parse_charstrings( decoder, charstring,
                                             charstring_len );
      decoder->seac = FALSE;

      cff_free_glyph_data( face, &charstring, charstring_len );

      if ( error )
        goto Exit;
    }

    /* Restore the left side bearing, advance and glyph width */
    /* of the base character.                                 */
    builder->left_bearing = left_bearing;
    builder->advance      = advance;
    decoder->glyph_width  = glyph_width;

    builder->pos_x = 0;
    builder->pos_y = 0;

  Exit:
    return error;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    cff_decoder_parse_charstrings                                      */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Parses a given Type 2 charstrings program.                         */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    decoder         :: The current Type 1 decoder.                     */
  /*                                                                       */
  /* <Input>                                                               */
  /*    charstring_base :: The base of the charstring stream.              */
  /*                                                                       */
  /*    charstring_len  :: The length in bytes of the charstring stream.   */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_LOCAL_DEF( FT_Error )
  cff_decoder_parse_charstrings( CFF_Decoder*  decoder,
                                 FT_Byte*      charstring_base,
                                 FT_ULong      charstring_len )
  {
    FT_Error           error;
    CFF_Decoder_Zone*  zone;
    FT_Byte*           ip;
    FT_Byte*           limit;
    CFF_Builder*       builder = &decoder->builder;
    FT_Pos             x, y;
    FT_Fixed           seed;
    FT_Fixed*          stack;
    FT_Int             charstring_type =
                         decoder->cff->top_font.font_dict.charstring_type;

    T2_Hints_Funcs     hinter;


    /* set default width */
    decoder->num_hints  = 0;
    decoder->read_width = 1;

    /* compute random seed from stack address of parameter */
    seed = (FT_Fixed)( ( (FT_PtrDist)(char*)&seed              ^
                         (FT_PtrDist)(char*)&decoder           ^
                         (FT_PtrDist)(char*)&charstring_base ) &
                         FT_ULONG_MAX ) ;
    seed = ( seed ^ ( seed >> 10 ) ^ ( seed >> 20 ) ) & 0xFFFFL;
    if ( seed == 0 )
      seed = 0x7384;

    /* initialize the decoder */
    decoder->top  = decoder->stack;
    decoder->zone = decoder->zones;
    zone          = decoder->zones;
    stack         = decoder->top;

    hinter = (T2_Hints_Funcs)builder->hints_funcs;

    builder->path_begun = 0;

    zone->base           = charstring_base;
    limit = zone->limit  = charstring_base + charstring_len;
    ip    = zone->cursor = zone->base;

    error = CFF_Err_Ok;

    x = builder->pos_x;
    y = builder->pos_y;

    /* begin hints recording session, if any */
    if ( hinter )
      hinter->open( hinter->hints );

    /* now execute loop */
    while ( ip < limit )
    {
      CFF_Operator  op;
      FT_Byte       v;


      /********************************************************************/
      /*                                                                  */
      /* Decode operator or operand                                       */
      /*                                                                  */
      v = *ip++;
      if ( v >= 32 || v == 28 )
      {
        FT_Int    shift = 16;
        FT_Int32  val;


        /* this is an operand, push it on the stack */
        if ( v == 28 )
        {
          if ( ip + 1 >= limit )
            goto Syntax_Error;
          val = (FT_Short)( ( (FT_Short)ip[0] << 8 ) | ip[1] );
          ip += 2;
        }
        else if ( v < 247 )
          val = (FT_Int32)v - 139;
        else if ( v < 251 )
        {
          if ( ip >= limit )
            goto Syntax_Error;
          val = ( (FT_Int32)v - 247 ) * 256 + *ip++ + 108;
        }
        else if ( v < 255 )
        {
          if ( ip >= limit )
            goto Syntax_Error;
          val = -( (FT_Int32)v - 251 ) * 256 - *ip++ - 108;
        }
        else
        {
          if ( ip + 3 >= limit )
            goto Syntax_Error;
          val = ( (FT_Int32)ip[0] << 24 ) |
                ( (FT_Int32)ip[1] << 16 ) |
                ( (FT_Int32)ip[2] <<  8 ) |
                            ip[3];
          ip    += 4;
          if ( charstring_type == 2 )
            shift = 0;
        }
        if ( decoder->top - stack >= CFF_MAX_OPERANDS )
          goto Stack_Overflow;

        val           <<= shift;
        *decoder->top++ = val;

#ifdef FT_DEBUG_LEVEL_TRACE
        if ( !( val & 0xFFFFL ) )
          FT_TRACE4(( " %ld", (FT_Int32)( val >> 16 ) ));
        else
          FT_TRACE4(( " %.2f", val / 65536.0 ));
#endif

      }
      else
      {
        /* The specification says that normally arguments are to be taken */
        /* from the bottom of the stack.  However, this seems not to be   */
        /* correct, at least for Acroread 7.0.8 on GNU/Linux: It pops the */
        /* arguments similar to a PS interpreter.                         */

        FT_Fixed*  args     = decoder->top;
        FT_Int     num_args = (FT_Int)( args - decoder->stack );
        FT_Int     req_args;


        /* find operator */
        op = cff_op_unknown;

        switch ( v )
        {
        case 1:
          op = cff_op_hstem;
          break;
        case 3:
          op = cff_op_vstem;
          break;
        case 4:
          op = cff_op_vmoveto;
          break;
        case 5:
          op = cff_op_rlineto;
          break;
        case 6:
          op = cff_op_hlineto;
          break;
        case 7:
          op = cff_op_vlineto;
          break;
        case 8:
          op = cff_op_rrcurveto;
          break;
        case 9:
          op = cff_op_closepath;
          break;
        case 10:
          op = cff_op_callsubr;
          break;
        case 11:
          op = cff_op_return;
          break;
        case 12:
          {
            if ( ip >= limit )
              goto Syntax_Error;
            v = *ip++;

            switch ( v )
            {
            case 0:
              op = cff_op_dotsection;
              break;
            case 1: /* this is actually the Type1 vstem3 operator */
              op = cff_op_vstem;
              break;
            case 2: /* this is actually the Type1 hstem3 operator */
              op = cff_op_hstem;
              break;
            case 3:
              op = cff_op_and;
              break;
            case 4:
              op = cff_op_or;
              break;
            case 5:
              op = cff_op_not;
              break;
            case 6:
              op = cff_op_seac;
              break;
            case 7:
              op = cff_op_sbw;
              break;
            case 8:
              op = cff_op_store;
              break;
            case 9:
              op = cff_op_abs;
              break;
            case 10:
              op = cff_op_add;
              break;
            case 11:
              op = cff_op_sub;
              break;
            case 12:
              op = cff_op_div;
              break;
            case 13:
              op = cff_op_load;
              break;
            case 14:
              op = cff_op_neg;
              break;
            case 15:
              op = cff_op_eq;
              break;
            case 16:
              op = cff_op_callothersubr;
              break;
            case 17:
              op = cff_op_pop;
              break;
            case 18:
              op = cff_op_drop;
              break;
            case 20:
              op = cff_op_put;
              break;
            case 21:
              op = cff_op_get;
              break;
            case 22:
              op = cff_op_ifelse;
              break;
            case 23:
              op = cff_op_random;
              break;
            case 24:
              op = cff_op_mul;
              break;
            case 26:
              op = cff_op_sqrt;
              break;
            case 27:
              op = cff_op_dup;
              break;
            case 28:
              op = cff_op_exch;
              break;
            case 29:
              op = cff_op_index;
              break;
            case 30:
              op = cff_op_roll;
              break;
            case 33:
              op = cff_op_setcurrentpoint;
              break;
            case 34:
              op = cff_op_hflex;
              break;
            case 35:
              op = cff_op_flex;
              break;
            case 36:
              op = cff_op_hflex1;
              break;
            case 37:
              op = cff_op_flex1;
              break;
            default:
              FT_TRACE4(( " unknown op (12, %d)\n", v ));
              break;
            }
          }
          break;
        case 13:
          op = cff_op_hsbw;
          break;
        case 14:
          op = cff_op_endchar;
          break;
        case 16:
          op = cff_op_blend;
          break;
        case 18:
          op = cff_op_hstemhm;
          break;
        case 19:
          op = cff_op_hintmask;
          break;
        case 20:
          op = cff_op_cntrmask;
          break;
        case 21:
          op = cff_op_rmoveto;
          break;
        case 22:
          op = cff_op_hmoveto;
          break;
        case 23:
          op = cff_op_vstemhm;
          break;
        case 24:
          op = cff_op_rcurveline;
          break;
        case 25:
          op = cff_op_rlinecurve;
          break;
        case 26:
          op = cff_op_vvcurveto;
          break;
        case 27:
          op = cff_op_hhcurveto;
          break;
        case 29:
          op = cff_op_callgsubr;
          break;
        case 30:
          op = cff_op_vhcurveto;
          break;
        case 31:
          op = cff_op_hvcurveto;
          break;
        default:
          FT_TRACE4(( " unknown op (%d)\n", v ));
          break;
        }

        if ( op == cff_op_unknown )
          continue;

        /* check arguments */
        req_args = cff_argument_counts[op];
        if ( req_args & CFF_COUNT_CHECK_WIDTH )
        {
          if ( num_args > 0 && decoder->read_width )
          {
            /* If `nominal_width' is non-zero, the number is really a      */
            /* difference against `nominal_width'.  Else, the number here  */
            /* is truly a width, not a difference against `nominal_width'. */
            /* If the font does not set `nominal_width', then              */
            /* `nominal_width' defaults to zero, and so we can set         */
            /* `glyph_width' to `nominal_width' plus number on the stack   */
            /* -- for either case.                                         */

            FT_Int  set_width_ok;


            switch ( op )
            {
            case cff_op_hmoveto:
            case cff_op_vmoveto:
              set_width_ok = num_args & 2;
              break;

            case cff_op_hstem:
            case cff_op_vstem:
            case cff_op_hstemhm:
            case cff_op_vstemhm:
            case cff_op_rmoveto:
            case cff_op_hintmask:
            case cff_op_cntrmask:
              set_width_ok = num_args & 1;
              break;

            case cff_op_endchar:
              /* If there is a width specified for endchar, we either have */
              /* 1 argument or 5 arguments.  We like to argue.             */
              set_width_ok = ( num_args == 5 ) || ( num_args == 1 );
              break;

            default:
              set_width_ok = 0;
              break;
            }

            if ( set_width_ok )
            {
              decoder->glyph_width = decoder->nominal_width +
                                       ( stack[0] >> 16 );

              if ( decoder->width_only )
              {
                /* we only want the advance width; stop here */
                break;
              }

              /* Consumed an argument. */
              num_args--;
            }
          }

          decoder->read_width = 0;
          req_args            = 0;
        }

        req_args &= 0x000F;
        if ( num_args < req_args )
          goto Stack_Underflow;
        args     -= req_args;
        num_args -= req_args;

        /* At this point, `args' points to the first argument of the  */
        /* operand in case `req_args' isn't zero.  Otherwise, we have */
        /* to adjust `args' manually.                                 */

        /* Note that we only pop arguments from the stack which we    */
        /* really need and can digest so that we can continue in case */
        /* of superfluous stack elements.                             */

        switch ( op )
        {
        case cff_op_hstem:
        case cff_op_vstem:
        case cff_op_hstemhm:
        case cff_op_vstemhm:
          /* the number of arguments is always even here */
          FT_TRACE4((
              op == cff_op_hstem   ? " hstem\n"   :
            ( op == cff_op_vstem   ? " vstem\n"   :
            ( op == cff_op_hstemhm ? " hstemhm\n" : " vstemhm\n" ) ) ));

          if ( hinter )
            hinter->stems( hinter->hints,
                           ( op == cff_op_hstem || op == cff_op_hstemhm ),
                           num_args / 2,
                           args - ( num_args & ~1 ) );

          decoder->num_hints += num_args / 2;
          args = stack;
          break;

        case cff_op_hintmask:
        case cff_op_cntrmask:
          FT_TRACE4(( op == cff_op_hintmask ? " hintmask" : " cntrmask" ));

          /* implement vstem when needed --                        */
          /* the specification doesn't say it, but this also works */
          /* with the 'cntrmask' operator                          */
          /*                                                       */
          if ( num_args > 0 )
          {
            if ( hinter )
              hinter->stems( hinter->hints,
                             0,
                             num_args / 2,
                             args - ( num_args & ~1 ) );

            decoder->num_hints += num_args / 2;
          }

          /* In a valid charstring there must be at least one byte */
          /* after `hintmask' or `cntrmask' (e.g., for a `return'  */
          /* instruction).  Additionally, there must be space for  */
          /* `num_hints' bits.                                     */

          if ( ( ip + ( ( decoder->num_hints + 7 ) >> 3 ) ) >= limit )
            goto Syntax_Error;

          if ( hinter )
          {
            if ( op == cff_op_hintmask )
              hinter->hintmask( hinter->hints,
                                builder->current->n_points,
                                decoder->num_hints,
                                ip );
            else
              hinter->counter( hinter->hints,
                               decoder->num_hints,
                               ip );
          }

#ifdef FT_DEBUG_LEVEL_TRACE
          {
            FT_UInt maskbyte;


            FT_TRACE4(( " (maskbytes:" ));

            for ( maskbyte = 0;
                  maskbyte < (FT_UInt)( ( decoder->num_hints + 7 ) >> 3 );
                  maskbyte++, ip++ )
              FT_TRACE4(( " 0x%02X", *ip ));

            FT_TRACE4(( ")\n" ));
          }
#else
          ip += ( decoder->num_hints + 7 ) >> 3;
#endif
          args = stack;
          break;

        case cff_op_rmoveto:
          FT_TRACE4(( " rmoveto\n" ));

          cff_builder_close_contour( builder );
          builder->path_begun = 0;
          x   += args[-2];
          y   += args[-1];
          args = stack;
          break;

        case cff_op_vmoveto:
          FT_TRACE4(( " vmoveto\n" ));

          cff_builder_close_contour( builder );
          builder->path_begun = 0;
          y   += args[-1];
          args = stack;
          break;

        case cff_op_hmoveto:
          FT_TRACE4(( " hmoveto\n" ));

          cff_builder_close_contour( builder );
          builder->path_begun = 0;
          x   += args[-1];
          args = stack;
          break;

        case cff_op_rlineto:
          FT_TRACE4(( " rlineto\n" ));

          if ( cff_builder_start_point ( builder, x, y ) ||
               check_points( builder, num_args / 2 )     )
            goto Fail;

          if ( num_args < 2 )
            goto Stack_Underflow;

          args -= num_args & ~1;
          while ( args < decoder->top )
          {
            x += args[0];
            y += args[1];
            cff_builder_add_point( builder, x, y, 1 );
            args += 2;
          }
          args = stack;
          break;

        case cff_op_hlineto:
        case cff_op_vlineto:
          {
            FT_Int  phase = ( op == cff_op_hlineto );


            FT_TRACE4(( op == cff_op_hlineto ? " hlineto\n"
                                             : " vlineto\n" ));

            if ( num_args < 0 )
              goto Stack_Underflow;

            /* there exist subsetted fonts (found in PDFs) */
            /* which call `hlineto' without arguments      */
            if ( num_args == 0 )
              break;

            if ( cff_builder_start_point ( builder, x, y ) ||
                 check_points( builder, num_args )         )
              goto Fail;

            args = stack;
            while ( args < decoder->top )
            {
              if ( phase )
                x += args[0];
              else
                y += args[0];

              if ( cff_builder_add_point1( builder, x, y ) )
                goto Fail;

              args++;
              phase ^= 1;
            }
            args = stack;
          }
          break;

        case cff_op_rrcurveto:
          {
            FT_Int  nargs;


            FT_TRACE4(( " rrcurveto\n" ));

            if ( num_args < 6 )
              goto Stack_Underflow;

            nargs = num_args - num_args % 6;

            if ( cff_builder_start_point ( builder, x, y ) ||
                 check_points( builder, nargs / 2 )     )
              goto Fail;

            args -= nargs;
            while ( args < decoder->top )
            {
              x += args[0];
              y += args[1];
              cff_builder_add_point( builder, x, y, 0 );
              x += args[2];
              y += args[3];
              cff_builder_add_point( builder, x, y, 0 );
              x += args[4];
              y += args[5];
              cff_builder_add_point( builder, x, y, 1 );
              args += 6;
            }
            args = stack;
          }
          break;

        case cff_op_vvcurveto:
          {
            FT_Int  nargs;


            FT_TRACE4(( " vvcurveto\n" ));

            if ( num_args < 4 )
              goto Stack_Underflow;

            /* if num_args isn't of the form 4n or 4n+1, */
            /* we enforce it by clearing the second bit  */

            nargs = num_args & ~2;

            if ( cff_builder_start_point( builder, x, y ) )
              goto Fail;

            args -= nargs;

            if ( nargs & 1 )
            {
              x += args[0];
              args++;
              nargs--;
            }

            if ( check_points( builder, 3 * ( nargs / 4 ) ) )
              goto Fail;

            while ( args < decoder->top )
            {
              y += args[0];
              cff_builder_add_point( builder, x, y, 0 );
              x += args[1];
              y += args[2];
              cff_builder_add_point( builder, x, y, 0 );
              y += args[3];
              cff_builder_add_point( builder, x, y, 1 );
              args += 4;
            }
            args = stack;
          }
          break;

        case cff_op_hhcurveto:
          {
            FT_Int  nargs;


            FT_TRACE4(( " hhcurveto\n" ));

            if ( num_args < 4 )
              goto Stack_Underflow;

            /* if num_args isn't of the form 4n or 4n+1, */
            /* we enforce it by clearing the second bit  */

            nargs = num_args & ~2;

            if ( cff_builder_start_point( builder, x, y ) )
              goto Fail;

            args -= nargs;
            if ( nargs & 1 )
            {
              y += args[0];
              args++;
              nargs--;
            }

            if ( check_points( builder, 3 * ( nargs / 4 ) ) )
              goto Fail;

            while ( args < decoder->top )
            {
              x += args[0];
              cff_builder_add_point( builder, x, y, 0 );
              x += args[1];
              y += args[2];
              cff_builder_add_point( builder, x, y, 0 );
              x += args[3];
              cff_builder_add_point( builder, x, y, 1 );
              args += 4;
            }
            args = stack;
          }
          break;

        case cff_op_vhcurveto:
        case cff_op_hvcurveto:
          {
            FT_Int  phase;
            FT_Int  nargs;


            FT_TRACE4(( op == cff_op_vhcurveto ? " vhcurveto\n"
                                               : " hvcurveto\n" ));

            if ( cff_builder_start_point( builder, x, y ) )
              goto Fail;

            if ( num_args < 4 )
              goto Stack_Underflow;

            /* if num_args isn't of the form 8n, 8n+1, 8n+4, or 8n+5, */
            /* we enforce it by clearing the second bit               */

            nargs = num_args & ~2;

            args -= nargs;
            if ( check_points( builder, ( nargs / 4 ) * 3 ) )
              goto Stack_Underflow;

            phase = ( op == cff_op_hvcurveto );

            while ( nargs >= 4 )
            {
              nargs -= 4;
              if ( phase )
              {
                x += args[0];
                cff_builder_add_point( builder, x, y, 0 );
                x += args[1];
                y += args[2];
                cff_builder_add_point( builder, x, y, 0 );
                y += args[3];
                if ( nargs == 1 )
                  x += args[4];
                cff_builder_add_point( builder, x, y, 1 );
              }
              else
              {
                y += args[0];
                cff_builder_add_point( builder, x, y, 0 );
                x += args[1];
                y += args[2];
                cff_builder_add_point( builder, x, y, 0 );
                x += args[3];
                if ( nargs == 1 )
                  y += args[4];
                cff_builder_add_point( builder, x, y, 1 );
              }
              args  += 4;
              phase ^= 1;
            }
            args = stack;
          }
          break;

        case cff_op_rlinecurve:
          {
            FT_Int  num_lines;
            FT_Int  nargs;


            FT_TRACE4(( " rlinecurve\n" ));

            if ( num_args < 8 )
              goto Stack_Underflow;

            nargs     = num_args & ~1;
            num_lines = ( nargs - 6 ) / 2;…