]>
Commit | Line | Data |
---|---|---|
15c0b25d AP |
1 | // Copyright 2011 The Go Authors. All rights reserved. |
2 | // Use of this source code is governed by a BSD-style | |
3 | // license that can be found in the LICENSE file. | |
4 | ||
5 | package norm | |
6 | ||
7 | type valueRange struct { | |
8 | value uint16 // header: value:stride | |
9 | lo, hi byte // header: lo:n | |
10 | } | |
11 | ||
12 | type sparseBlocks struct { | |
13 | values []valueRange | |
14 | offset []uint16 | |
15 | } | |
16 | ||
17 | var nfcSparse = sparseBlocks{ | |
18 | values: nfcSparseValues[:], | |
19 | offset: nfcSparseOffset[:], | |
20 | } | |
21 | ||
22 | var nfkcSparse = sparseBlocks{ | |
23 | values: nfkcSparseValues[:], | |
24 | offset: nfkcSparseOffset[:], | |
25 | } | |
26 | ||
27 | var ( | |
28 | nfcData = newNfcTrie(0) | |
29 | nfkcData = newNfkcTrie(0) | |
30 | ) | |
31 | ||
32 | // lookupValue determines the type of block n and looks up the value for b. | |
33 | // For n < t.cutoff, the block is a simple lookup table. Otherwise, the block | |
34 | // is a list of ranges with an accompanying value. Given a matching range r, | |
35 | // the value for b is by r.value + (b - r.lo) * stride. | |
36 | func (t *sparseBlocks) lookup(n uint32, b byte) uint16 { | |
37 | offset := t.offset[n] | |
38 | header := t.values[offset] | |
39 | lo := offset + 1 | |
40 | hi := lo + uint16(header.lo) | |
41 | for lo < hi { | |
42 | m := lo + (hi-lo)/2 | |
43 | r := t.values[m] | |
44 | if r.lo <= b && b <= r.hi { | |
45 | return r.value + uint16(b-r.lo)*header.value | |
46 | } | |
47 | if b < r.lo { | |
48 | hi = m | |
49 | } else { | |
50 | lo = m + 1 | |
51 | } | |
52 | } | |
53 | return 0 | |
54 | } |