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+/* __mpn_sub_n -- Add two limb vectors of the same length > 0 and store
+ sum in a third limb vector. 64 bit S/390 version.
+ Copyright (C) 2001 Free Software Foundation, Inc.
+ Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
+ This file is part of the GNU MP Library.
+
+ The GNU C 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 C 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 C Library; see the file COPYING.LIB. If not,
+ write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+/* INPUT PARAMETERS
+ %r2 = res_ptr
+ %r3 = s1_ptr
+ %r4 = s2_ptr
+ %r5 = size. */
+
+#include "sysdep.h"
+#include "asm-syntax.h"
+
+ENTRY(__mpn_sub_n)
+ stg %r6,48(%r15) # save register 6
+ sgr %r1,%r1
+ lghi %r0,1 # cannot use ahi to add carry, use slr
+.L0: lg %r6,0(%r1,%r3) # .L0 -> no carry from last sub
+ slg %r6,0(%r1,%r4)
+ stg %r6,0(%r1,%r2)
+ la %r1,8(%r1)
+ brc 4,.L3
+.L1: brct %r5,.L0
+ slgr %r2,%r2 # no last carry to return
+ j .Lexit
+.L2: lg %r6,0(%r1,%r3) # .L2 -> carry from last sub
+ slg %r6,0(%r1,%r4)
+ brc 4,.L4
+ slgr %r6,%r0 # no carry yet, add carry from last sub
+ stg %r6,0(%r1,%r2)
+ la %r1,8(%r1)
+ brc 11,.L1 # new carry ?
+.L3: brct %r5,.L2
+ lgr %r2,%r0 # return last carry
+ j .Lexit
+.L4: slgr %r6,%r0 # already a carry, add carry from last sub
+ stg %r6,0(%r1,%r2)
+ la %r1,8(%r1)
+ brct %r5,.L2
+ lgr %r2,%r0 # return last carry
+.Lexit: lg %r6,48(%r15) # restore register 6
+ br %r14
+END(__mpn_sub_n)