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