1 /*
2 *
3 * (C) Copyright IBM Corp. 1998-2013 - 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 */
lookupSegment(const LETableReference & base,const LookupSegment * segments,LEGlyphID glyph,LEErrorCode & success) const27 const LookupSegment *BinarySearchLookupTable::lookupSegment(const LETableReference &base, const LookupSegment *segments, LEGlyphID glyph, LEErrorCode &success) const
28 {
29
30 le_int16 unity = SWAPW(unitSize);
31 le_int16 probe = SWAPW(searchRange);
32 le_int16 extra = SWAPW(rangeShift);
33 TTGlyphID ttGlyph = (TTGlyphID) LE_GET_GLYPH(glyph);
34 LEReferenceTo<LookupSegment> entry(base, success, segments);
35 LEReferenceTo<LookupSegment> trial(entry, success, extra);
36
37 if(LE_FAILURE(success)) return NULL;
38
39 if (SWAPW(trial->lastGlyph) <= ttGlyph) {
40 entry = trial;
41 }
42
43 while (probe > unity && LE_SUCCESS(success)) {
44 probe >>= 1;
45 trial = entry; // copy
46 trial.addOffset(probe, success);
47
48 if (SWAPW(trial->lastGlyph) <= ttGlyph) {
49 entry = trial;
50 }
51 }
52
53 if (SWAPW(entry->firstGlyph) <= ttGlyph) {
54 return entry.getAlias();
55 }
56
57 return NULL;
58 }
59
lookupSingle(const LETableReference & base,const LookupSingle * entries,LEGlyphID glyph,LEErrorCode & success) const60 const LookupSingle *BinarySearchLookupTable::lookupSingle(const LETableReference &base, const LookupSingle *entries, LEGlyphID glyph, LEErrorCode &success) const
61 {
62 le_int16 unity = SWAPW(unitSize);
63 le_int16 probe = SWAPW(searchRange);
64 le_int16 extra = SWAPW(rangeShift);
65 TTGlyphID ttGlyph = (TTGlyphID) LE_GET_GLYPH(glyph);
66 LEReferenceTo<LookupSingle> entry(base, success, entries);
67 LEReferenceTo<LookupSingle> trial(entry, success, extra);
68
69 if (SWAPW(trial->glyph) <= ttGlyph) {
70 entry = trial;
71 }
72
73 while (probe > unity && LE_SUCCESS(success)) {
74 probe >>= 1;
75 trial = entry;
76 trial.addOffset(probe, success);
77
78 if (SWAPW(trial->glyph) <= ttGlyph) {
79 entry = trial;
80 }
81 }
82
83 if (SWAPW(entry->glyph) == ttGlyph) {
84 return entry.getAlias();
85 }
86
87 return NULL;
88 }
89
90 U_NAMESPACE_END
91