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+// Inferno's libkern/memmove-386.s
+// http://code.google.com/p/inferno-os/source/browse/libkern/memmove-386.s
+//
+// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
+// Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved.
+// Portions Copyright 2009 The Go Authors. All rights reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#include "../../cmd/ld/textflag.h"
+
+TEXT runtime·memmove(SB), NOSPLIT, $0-12
+ MOVL to+0(FP), DI
+ MOVL fr+4(FP), SI
+ MOVL n+8(FP), BX
+
+ // REP instructions have a high startup cost, so we handle small sizes
+ // with some straightline code. The REP MOVSL instruction is really fast
+ // for large sizes. The cutover is approximately 1K.
+tail:
+ TESTL BX, BX
+ JEQ move_0
+ CMPL BX, $2
+ JBE move_1or2
+ CMPL BX, $4
+ JBE move_3or4
+ CMPL BX, $8
+ JBE move_5through8
+ CMPL BX, $16
+ JBE move_9through16
+
+/*
+ * check and set for backwards
+ */
+ CMPL SI, DI
+ JLS back
+
+/*
+ * forward copy loop
+ */
+forward:
+ MOVL BX, CX
+ SHRL $2, CX
+ ANDL $3, BX
+
+ REP; MOVSL
+ JMP tail
+/*
+ * check overlap
+ */
+back:
+ MOVL SI, CX
+ ADDL BX, CX
+ CMPL CX, DI
+ JLS forward
+/*
+ * whole thing backwards has
+ * adjusted addresses
+ */
+
+ ADDL BX, DI
+ ADDL BX, SI
+ STD
+
+/*
+ * copy
+ */
+ MOVL BX, CX
+ SHRL $2, CX
+ ANDL $3, BX
+
+ SUBL $4, DI
+ SUBL $4, SI
+ REP; MOVSL
+
+ CLD
+ ADDL $4, DI
+ ADDL $4, SI
+ SUBL BX, DI
+ SUBL BX, SI
+ JMP tail
+
+move_1or2:
+ MOVB (SI), AX
+ MOVB -1(SI)(BX*1), CX
+ MOVB AX, (DI)
+ MOVB CX, -1(DI)(BX*1)
+move_0:
+ RET
+move_3or4:
+ MOVW (SI), AX
+ MOVW -2(SI)(BX*1), CX
+ MOVW AX, (DI)
+ MOVW CX, -2(DI)(BX*1)
+ RET
+move_5through8:
+ MOVL (SI), AX
+ MOVL -4(SI)(BX*1), CX
+ MOVL AX, (DI)
+ MOVL CX, -4(DI)(BX*1)
+ RET
+move_9through16:
+ MOVL (SI), AX
+ MOVL 4(SI), CX
+ MOVL -8(SI)(BX*1), DX
+ MOVL -4(SI)(BX*1), BP
+ MOVL AX, (DI)
+ MOVL CX, 4(DI)
+ MOVL DX, -8(DI)(BX*1)
+ MOVL BP, -4(DI)(BX*1)
+ RET