| | 1 | /* |
| | 2 | * |
| | 3 | * (C) Copyright IBM Corp. 1998-2004 - All Rights Reserved |
| | 4 | * |
| | 5 | */ |
| | 6 | |
| | 7 | #include "LETypes.h" |
| | 8 | #include "LayoutTables.h" |
| | 9 | #include "LookupTables.h" |
| | 10 | #include "LESwaps.h" |
| | 11 | |
| | 12 | U_NAMESPACE_BEGIN |
| | 13 | |
| | 14 | /* |
| | 15 | These are the rolled-up versions of the uniform binary search. |
| | 16 | Someday, if we need more performance, we can un-roll them. |
| | 17 | |
| | 18 | Note: I put these in the base class, so they only have to |
| | 19 | be written once. Since the base class doesn't define the |
| | 20 | segment table, these routines assume that it's right after |
| | 21 | the binary search header. |
| | 22 | |
| | 23 | Another way to do this is to put each of these routines in one |
| | 24 | of the derived classes, and implement it in the others by casting |
| | 25 | the "this" pointer to the type that has the implementation. |
| | 26 | */ |
| | 27 | const LookupSegment *BinarySearchLookupTable::lookupSegment(const LookupSegment *segments, LEGlyphID glyph) const |
| | 28 | { |
| | 29 | le_int16 unity = SWAPW(unitSize); |
| | 30 | le_int16 probe = SWAPW(searchRange); |
| | 31 | le_int16 extra = SWAPW(rangeShift); |
| | 32 | TTGlyphID ttGlyph = (TTGlyphID) LE_GET_GLYPH(glyph); |
| | 33 | const LookupSegment *entry = segments; |
| | 34 | const LookupSegment *trial = (const LookupSegment *) ((char *) entry + extra); |
| | 35 | |
| | 36 | if (SWAPW(trial->lastGlyph) <= ttGlyph) { |
| | 37 | entry = trial; |
| | 38 | } |
| | 39 | |
| | 40 | while (probe > unity) { |
| | 41 | probe >>= 1; |
| | 42 | trial = (const LookupSegment *) ((char *) entry + probe); |
| | 43 | |
| | 44 | if (SWAPW(trial->lastGlyph) <= ttGlyph) { |
| | 45 | entry = trial; |
| | 46 | } |
| | 47 | } |
| | 48 | |
| | 49 | if (SWAPW(entry->firstGlyph) <= ttGlyph) { |
| | 50 | return entry; |
| | 51 | } |
| | 52 | |
| | 53 | return NULL; |
| | 54 | } |
| | 55 | |
| | 56 | const LookupSingle *BinarySearchLookupTable::lookupSingle(const LookupSingle *entries, LEGlyphID glyph) const |
| | 57 | { |
| | 58 | le_int16 unity = SWAPW(unitSize); |
| | 59 | le_int16 probe = SWAPW(searchRange); |
| | 60 | le_int16 extra = SWAPW(rangeShift); |
| | 61 | TTGlyphID ttGlyph = (TTGlyphID) LE_GET_GLYPH(glyph); |
| | 62 | const LookupSingle *entry = entries; |
| | 63 | const LookupSingle *trial = (const LookupSingle *) ((char *) entry + extra); |
| | 64 | |
| | 65 | if (SWAPW(trial->glyph) <= ttGlyph) { |
| | 66 | entry = trial; |
| | 67 | } |
| | 68 | |
| | 69 | while (probe > unity) { |
| | 70 | probe >>= 1; |
| | 71 | trial = (const LookupSingle *) ((char *) entry + probe); |
| | 72 | |
| | 73 | if (SWAPW(trial->glyph) <= ttGlyph) { |
| | 74 | entry = trial; |
| | 75 | } |
| | 76 | } |
| | 77 | |
| | 78 | if (SWAPW(entry->glyph) == ttGlyph) { |
| | 79 | return entry; |
| | 80 | } |
| | 81 | |
| | 82 | return NULL; |
| | 83 | } |
| | 84 | |
| | 85 | U_NAMESPACE_END |
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