1 // Copyright 2012 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 flate 6 7 // forwardCopy is like the built-in copy function except that it always goes 8 // forward from the start, even if the dst and src overlap. 9 // It is equivalent to: 10 // for i := 0; i < n; i++ { 11 // mem[dst+i] = mem[src+i] 12 // } 13 func forwardCopy(mem []byte, dst, src, n int) { 14 if dst <= src { 15 copy(mem[dst:dst+n], mem[src:src+n]) 16 return 17 } 18 for { 19 if dst >= src+n { 20 copy(mem[dst:dst+n], mem[src:src+n]) 21 return 22 } 23 // There is some forward overlap. The destination 24 // will be filled with a repeated pattern of mem[src:src+k]. 25 // We copy one instance of the pattern here, then repeat. 26 // Each time around this loop k will double. 27 k := dst - src 28 copy(mem[dst:dst+k], mem[src:src+k]) 29 n -= k 30 dst += k 31 } 32 } 33
