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- // Copyright 2011 The Go Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
- package norm
- type valueRange struct {
- value uint16 // header: value:stride
- lo, hi byte // header: lo:n
- }
- type sparseBlocks struct {
- values []valueRange
- offset []uint16
- }
- var nfcSparse = sparseBlocks{
- values: nfcSparseValues[:],
- offset: nfcSparseOffset[:],
- }
- var nfkcSparse = sparseBlocks{
- values: nfkcSparseValues[:],
- offset: nfkcSparseOffset[:],
- }
- var (
- nfcData = newNfcTrie(0)
- nfkcData = newNfkcTrie(0)
- )
- // lookupValue determines the type of block n and looks up the value for b.
- // For n < t.cutoff, the block is a simple lookup table. Otherwise, the block
- // is a list of ranges with an accompanying value. Given a matching range r,
- // the value for b is by r.value + (b - r.lo) * stride.
- func (t *sparseBlocks) lookup(n uint32, b byte) uint16 {
- offset := t.offset[n]
- header := t.values[offset]
- lo := offset + 1
- hi := lo + uint16(header.lo)
- for lo < hi {
- m := lo + (hi-lo)/2
- r := t.values[m]
- if r.lo <= b && b <= r.hi {
- return r.value + uint16(b-r.lo)*header.value
- }
- if b < r.lo {
- hi = m
- } else {
- lo = m + 1
- }
- }
- return 0
- }
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