/* Subtract two limb vectors of equal, non-zero length for PowerPC.

   Copyright (C) 1997-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C 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 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

   Lesser General Public License for more details.

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

   License along with the GNU C Library; if not, see

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

#include <sysdep.h>

/* mp_limb_t mpn_sub_n (mp_ptr res_ptr, mp_srcptr s1_ptr, mp_srcptr s2_ptr,

                        mp_size_t size)

   Calculate s1-s2 and put result in res_ptr; return borrow, 0 or 1.  */

/* Note on optimisation: This code is optimal for the 601.  Almost every other

   possible 2-unrolled inner loop will not be.  Also, watch out for the

   alignment...  */

EALIGN (__mpn_sub_n, 3, 1)

/* Set up for loop below.  */

	mtcrf 0x01,r6

	srwi. r7,r6,1

	mtctr r7

	bt    31,L(2)

/* Set the carry (clear the borrow).  */

	subfc r0,r0,r0

/* Adjust pointers for loop.  */

	addi  r3,r3,-4

	addi  r4,r4,-4

	addi  r5,r5,-4

	b     L(0)

L(2):	lwz   r7,0(r5)

	lwz   r6,0(r4)

	subfc r6,r7,r6

	stw   r6,0(r3)

        beq   L(1)

/* Align start of loop to an odd word boundary to guarantee that the

   last two words can be fetched in one access (for 601).  This turns

   out to be important.  */

L(0):

	lwz   r9,4(r4)

	lwz   r8,4(r5)

	lwzu  r6,8(r4)

	lwzu  r7,8(r5)

	subfe r8,r8,r9

	stw   r8,4(r3)

	subfe r6,r7,r6

	stwu  r6,8(r3)

	bdnz  L(0)

/* Return the borrow. */

L(1):	subfe r3,r3,r3

	neg   r3,r3

	blr

END (__mpn_sub_n)