icuSources/layout/LigatureSubstProc.cpp

   1 /*
   2  *
   3  * (C) Copyright IBM Corp. 1998-2004 - All Rights Reserved
   4  *
   5  */
   6
   7 #include "LETypes.h"
   8 #include "MorphTables.h"
   9 #include "StateTables.h"
  10 #include "MorphStateTables.h"
  11 #include "SubtableProcessor.h"
  12 #include "StateTableProcessor.h"
  13 #include "LigatureSubstProc.h"
  14 #include "LEGlyphStorage.h"
  15 #include "LESwaps.h"
  16
  17 U_NAMESPACE_BEGIN
  18
  19 #define ExtendedComplement(m) ((le_int32) (~((le_uint32) (m))))
  20 #define SignBit(m) ((ExtendedComplement(m) >> 1) & (le_int32)(m))
  21 #define SignExtend(v,m) (((v) & SignBit(m))? ((v) | ExtendedComplement(m)): (v))
  22
  23 UOBJECT_DEFINE_RTTI_IMPLEMENTATION(LigatureSubstitutionProcessor)
  24
  25 LigatureSubstitutionProcessor::LigatureSubstitutionProcessor(const MorphSubtableHeader *morphSubtableHeader)
  26   : StateTableProcessor(morphSubtableHeader)
  27 {
  28     ligatureSubstitutionHeader = (const LigatureSubstitutionHeader *) morphSubtableHeader;
  29     ligatureActionTableOffset = SWAPW(ligatureSubstitutionHeader->ligatureActionTableOffset);
  30     componentTableOffset = SWAPW(ligatureSubstitutionHeader->componentTableOffset);
  31     ligatureTableOffset = SWAPW(ligatureSubstitutionHeader->ligatureTableOffset);
  32
  33     entryTable = (const LigatureSubstitutionStateEntry *) ((char *) &stateTableHeader->stHeader + entryTableOffset);
  34 }
  35
  36 LigatureSubstitutionProcessor::~LigatureSubstitutionProcessor()
  37 {
  38 }
  39
  40 void LigatureSubstitutionProcessor::beginStateTable()
  41 {
  42     m = -1;
  43 }
  44
  45 ByteOffset LigatureSubstitutionProcessor::processStateEntry(LEGlyphStorage &glyphStorage, le_int32 &currGlyph, EntryTableIndex index)
  46 {
  47     const LigatureSubstitutionStateEntry *entry = &entryTable[index];
  48     ByteOffset newState = SWAPW(entry->newStateOffset);
  49     le_int16 flags = SWAPW(entry->flags);
  50
  51     if (flags & lsfSetComponent) {
  52         if (++m >= nComponents) {
  53             m = 0;
  54         }
  55
  56         componentStack[m] = currGlyph;
  57     }
  58
  59     ByteOffset actionOffset = flags & lsfActionOffsetMask;
  60
  61     if (actionOffset != 0) {
  62         const LigatureActionEntry *ap = (const LigatureActionEntry *) ((char *) &ligatureSubstitutionHeader->stHeader + actionOffset);
  63         LigatureActionEntry action;
  64         le_int32 offset, i = 0;
  65         le_int32 stack[nComponents];
  66         le_int16 mm = -1;
  67
  68         do {
  69             le_uint32 componentGlyph = componentStack[m--];
  70
  71             action = SWAPL(*ap++);
  72
  73             if (m < 0) {
  74                 m = nComponents - 1;
  75             }
  76
  77             offset = action & lafComponentOffsetMask;
  78             if (offset != 0) {
  79                 const le_int16 *offsetTable = (const le_int16 *)((char *) &ligatureSubstitutionHeader->stHeader + 2 * SignExtend(offset, lafComponentOffsetMask));
  80
  81                 i += SWAPW(offsetTable[LE_GET_GLYPH(glyphStorage[componentGlyph])]);
  82
  83                 if (action & (lafLast | lafStore))  {
  84                     const TTGlyphID *ligatureOffset = (const TTGlyphID *) ((char *) &ligatureSubstitutionHeader->stHeader + i);
  85                     TTGlyphID ligatureGlyph = SWAPW(*ligatureOffset);
  86
  87                     glyphStorage[componentGlyph] = LE_SET_GLYPH(glyphStorage[componentGlyph], ligatureGlyph);
  88                     stack[++mm] = componentGlyph;
  89                     i = 0;
  90                 } else {
  91                     glyphStorage[componentGlyph] = LE_SET_GLYPH(glyphStorage[componentGlyph], 0xFFFF);
  92                 }
  93             }
  94         } while (!(action & lafLast));
  95
  96         while (mm >= 0) {
  97             if (++m >= nComponents) {
  98                 m = 0;
  99             }
 100
 101             componentStack[m] = stack[mm--];
 102         }
 103     }
 104
 105     if (!(flags & lsfDontAdvance)) {
 106         // should handle reverse too!
 107         currGlyph += 1;
 108     }
 109
 110     return newState;
 111 }
 112
 113 void LigatureSubstitutionProcessor::endStateTable()
 114 {
 115 }
 116
 117 U_NAMESPACE_END