sl@0: /*
sl@0:  *
sl@0:  * (C) Copyright IBM Corp. 1998-2004 - All Rights Reserved
sl@0:  *
sl@0:  */
sl@0: 
sl@0: #include "LETypes.h"
sl@0: #include "LayoutTables.h"
sl@0: #include "LookupTables.h"
sl@0: #include "LESwaps.h"
sl@0: 
sl@0: U_NAMESPACE_BEGIN
sl@0: 
sl@0: /*
sl@0:     These are the rolled-up versions of the uniform binary search.
sl@0:     Someday, if we need more performance, we can un-roll them.
sl@0:     
sl@0:     Note: I put these in the base class, so they only have to
sl@0:     be written once. Since the base class doesn't define the
sl@0:     segment table, these routines assume that it's right after
sl@0:     the binary search header.
sl@0: 
sl@0:     Another way to do this is to put each of these routines in one
sl@0:     of the derived classes, and implement it in the others by casting
sl@0:     the "this" pointer to the type that has the implementation.
sl@0: */ 
sl@0: const LookupSegment *BinarySearchLookupTable::lookupSegment(const LookupSegment *segments, LEGlyphID glyph) const
sl@0: {
sl@0:     le_int16  unity = SWAPW(unitSize);
sl@0:     le_int16  probe = SWAPW(searchRange);
sl@0:     le_int16  extra = SWAPW(rangeShift);
sl@0:     TTGlyphID ttGlyph = (TTGlyphID) LE_GET_GLYPH(glyph);
sl@0:     const LookupSegment *entry = segments;
sl@0:     const LookupSegment *trial = (const LookupSegment *) ((char *) entry + extra);
sl@0: 
sl@0:     if (SWAPW(trial->lastGlyph) <= ttGlyph) {
sl@0:         entry = trial;
sl@0:     }
sl@0: 
sl@0:     while (probe > unity) {
sl@0:         probe >>= 1;
sl@0:         trial = (const LookupSegment *) ((char *) entry + probe);
sl@0: 
sl@0:         if (SWAPW(trial->lastGlyph) <= ttGlyph) {
sl@0:             entry = trial;
sl@0:         }
sl@0:     }
sl@0: 
sl@0:     if (SWAPW(entry->firstGlyph) <= ttGlyph) {
sl@0:         return entry;
sl@0:     }
sl@0: 
sl@0:     return NULL;
sl@0: }
sl@0: 
sl@0: const LookupSingle *BinarySearchLookupTable::lookupSingle(const LookupSingle *entries, LEGlyphID glyph) const
sl@0: {
sl@0:     le_int16  unity = SWAPW(unitSize);
sl@0:     le_int16  probe = SWAPW(searchRange);
sl@0:     le_int16  extra = SWAPW(rangeShift);
sl@0:     TTGlyphID ttGlyph = (TTGlyphID) LE_GET_GLYPH(glyph);
sl@0:     const LookupSingle *entry = entries;
sl@0:     const LookupSingle *trial = (const LookupSingle *) ((char *) entry + extra);
sl@0: 
sl@0:     if (SWAPW(trial->glyph) <= ttGlyph) {
sl@0:         entry = trial;
sl@0:     }
sl@0: 
sl@0:     while (probe > unity) {
sl@0:         probe >>= 1;
sl@0:         trial = (const LookupSingle *) ((char *) entry + probe);
sl@0: 
sl@0:         if (SWAPW(trial->glyph) <= ttGlyph) {
sl@0:             entry = trial;
sl@0:         }
sl@0:     }
sl@0: 
sl@0:     if (SWAPW(entry->glyph) == ttGlyph) {
sl@0:         return entry;
sl@0:     }
sl@0: 
sl@0:     return NULL;
sl@0: }
sl@0: 
sl@0: U_NAMESPACE_END