glibc/sysdeps/s390/s390-32/sub_n.S

/* __mpn_sub_n -- Add two limb vectors of the same length > 0 and store
   sum in a third limb vector.
   Copyright (C) 2000, 2001 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 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., 59 Temple Place - Suite 330, Boston,
   MA 02111-1307, USA. */

/*
  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
	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)