1/* __mpn_sub_n -- Add two limb vectors of the same length > 0 and store
2   sum in a third limb vector.
3   Copyright (C) 2000-2021 Free Software Foundation, Inc.
4   This file is part of the GNU MP Library.
5
6   The GNU MP Library is free software; you can redistribute it and/or modify
7   it under the terms of the GNU Lesser General Public License as published by
8   the Free Software Foundation; either version 2.1 of the License, or (at your
9   option) any later version.
10
11   The GNU MP Library is distributed in the hope that it will be useful, but
12   WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
14   License for more details.
15
16   You should have received a copy of the GNU Lesser General Public License
17   along with the GNU MP Library; see the file COPYING.LIB.  If not,
18   see <https://www.gnu.org/licenses/>.  */
19
20/*
21  INPUT PARAMETERS
22  res_ptr	%r2
23  s1_ptr	%r3
24  s2_ptr	%r4
25  size		%r5
26*/
27
28#include "sysdep.h"
29#include "asm-syntax.h"
30
31ENTRY(__mpn_sub_n)
32	st     %r6,24(%r15)   # save register 6
33	cfi_offset (%r6, -72)
34	sr     %r1,%r1
35	lhi    %r0,1          # cannot use ahi to add carry, use slr
36.L0:    l      %r6,0(%r1,%r3) # .L0 -> no carry from last sub
37	sl     %r6,0(%r1,%r4)
38	st     %r6,0(%r1,%r2)
39	la     %r1,4(0,%r1)
40	brc    4,.L3
41.L1:    brct   %r5,.L0
42	slr    %r2,%r2        # no last carry to return
43	j      .Lexit
44.L2:    l      %r6,0(%r1,%r3) # .L2 -> carry from last sub
45	sl     %r6,0(%r1,%r4)
46	brc    4,.L4
47	slr    %r6,%r0        # no carry yet, add carry from last sub
48	st     %r6,0(%r1,%r2)
49	la     %r1,4(0,%r1)
50	brc    11,.L1         # new carry ?
51.L3:    brct   %r5,.L2
52	lr     %r2,%r0        # return last carry
53	j      .Lexit
54.L4:    slr    %r6,%r0        # already a carry, add carry from last sub
55	st     %r6,0(%r1,%r2)
56	la     %r1,4(0,%r1)
57	brct   %r5,.L2
58	lr     %r2,%r0        # return last carry
59.Lexit: l      %r6,24(%r15)   # restore register 6
60	br     %r14
61END(__mpn_sub_n)
62