/* __mpn_sub_n -- Add two limb vectors of the same length > 0 and store

   sum in a third limb vector.

   Copyright (C) 2000-2018 Free Software Foundation, Inc.

   Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).

   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 Lesser General Public License as published by

   the Free Software Foundation; either version 2.1 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 Lesser General Public

   License for more details.

   You should have received a copy of the GNU Lesser General Public License

   along with the GNU MP Library; see the file COPYING.LIB.  If not,

   see <http://www.gnu.org/licenses/>.  */

/*

  INPUT PARAMETERS

  res_ptr	%r2

  s1_ptr	%r3

  s2_ptr	%r4

  size		%r5

*/

#include "sysdep.h"

#include "asm-syntax.h"

ENTRY(__mpn_sub_n)

	st     %r6,24(%r15)   # save register 6

	cfi_offset (%r6, -72)

	sr     %r1,%r1

	lhi    %r0,1          # cannot use ahi to add carry, use slr

.L0:    l      %r6,0(%r1,%r3) # .L0 -> no carry from last sub

	sl     %r6,0(%r1,%r4)

	st     %r6,0(%r1,%r2)

	la     %r1,4(0,%r1)

	brc    4,.L3

.L1:    brct   %r5,.L0

	slr    %r2,%r2        # no last carry to return

	j      .Lexit

.L2:    l      %r6,0(%r1,%r3) # .L2 -> carry from last sub

	sl     %r6,0(%r1,%r4)

	brc    4,.L4

	slr    %r6,%r0        # no carry yet, add carry from last sub

	st     %r6,0(%r1,%r2)

	la     %r1,4(0,%r1)

	brc    11,.L1         # new carry ?

.L3:    brct   %r5,.L2

	lr     %r2,%r0        # return last carry

	j      .Lexit

.L4:    slr    %r6,%r0        # already a carry, add carry from last sub

	st     %r6,0(%r1,%r2)

	la     %r1,4(0,%r1)

	brct   %r5,.L2

	lr     %r2,%r0        # return last carry

.Lexit: l      %r6,24(%r15)   # restore register 6

	br     %r14

END(__mpn_sub_n)