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+/* mc68020 __mpn_sub_n -- Subtract two limb vectors of the same length > 0 and
+   store difference in a third limb vector.
+
+Copyright (C) 1992, 1994 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of the GNU Library General Public License as published by
+the Free Software Foundation; either version 2 of the License, or (at your
+option) any later version.
+
+The GNU MP Library is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
+License for more details.
+
+You should have received a copy of the GNU Library General Public License
+along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+/*
+  INPUT PARAMETERS
+  res_ptr	(sp + 4)
+  s1_ptr	(sp + 8)
+  s2_ptr	(sp + 16)
+  size		(sp + 12)
+*/
+
+#include "asm-syntax.h"
+
+	TEXT
+	ALIGN
+	GLOBL	___mpn_sub_n
+
+LAB(___mpn_sub_n)
+/* Save used registers on the stack.  */
+	INSN2(move,l	,MEM_PREDEC(sp),d2)
+	INSN2(move,l	,MEM_PREDEC(sp),a2)
+
+/* Copy the arguments to registers.  Better use movem?  */
+	INSN2(move,l	,a2,MEM_DISP(sp,12))
+	INSN2(move,l	,a0,MEM_DISP(sp,16))
+	INSN2(move,l	,a1,MEM_DISP(sp,20))
+	INSN2(move,l	,d2,MEM_DISP(sp,24))
+
+	INSN2(eor,w	,d2,#1)
+	INSN2(lsr,l	,d2,#1)
+	bcc L1
+	INSN2(subq,l	,d2,#1)		/* clears cy as side effect */
+
+LAB(Loop)
+	INSN2(move,l	,d0,MEM_POSTINC(a0))
+	INSN2(move,l	,d1,MEM_POSTINC(a1))
+	INSN2(subx,l	,d0,d1)
+	INSN2(move,l	,MEM_POSTINC(a2),d0)
+LAB(L1)	INSN2(move,l	,d0,MEM_POSTINC(a0))
+	INSN2(move,l	,d1,MEM_POSTINC(a1))
+	INSN2(subx,l	,d0,d1)
+	INSN2(move,l	,MEM_POSTINC(a2),d0)
+
+	dbf d2,Loop			/* loop until 16 lsb of %4 == -1 */
+	INSN2(subx,l	,d0,d0)		/* d0 <= -cy; save cy as 0 or -1 in d0 */
+	INSN2(sub,l	,d2,#0x10000)
+	bcs L2
+	INSN2(add,l	,d0,d0)		/* restore cy */
+	bra Loop
+
+LAB(L2)
+	INSN1(neg,l	,d0)
+
+/* Restore used registers from stack frame.  */
+	INSN2(move,l	,a2,MEM_POSTINC(sp))
+	INSN2(move,l	,d2,MEM_POSTINC(sp))
+
+	rts