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33 lines
905 B
33 lines
905 B
8 years ago
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// Copyright 2012 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 flate
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// forwardCopy is like the built-in copy function except that it always goes
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// forward from the start, even if the dst and src overlap.
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// It is equivalent to:
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// for i := 0; i < n; i++ {
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// mem[dst+i] = mem[src+i]
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// }
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func forwardCopy(mem []byte, dst, src, n int) {
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if dst <= src {
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copy(mem[dst:dst+n], mem[src:src+n])
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return
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}
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for {
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if dst >= src+n {
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copy(mem[dst:dst+n], mem[src:src+n])
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return
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}
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// There is some forward overlap. The destination
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// will be filled with a repeated pattern of mem[src:src+k].
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// We copy one instance of the pattern here, then repeat.
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// Each time around this loop k will double.
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k := dst - src
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copy(mem[dst:dst+k], mem[src:src+k])
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n -= k
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dst += k
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}
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}
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