/* mpn_add_n -- add (or subtract) bignums.

   Copyright (C) 2013-2018 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>

#include <arm-features.h>

	.syntax unified

	.text

#ifdef USE_AS_SUB_N

# define INITC	cmp r0, r0

# define OPC	sbcs

# define RETC	sbc r0, r0, r0; neg r0, r0

# define FUNC	__mpn_sub_n

#else

# define INITC	cmn r0, #0

# define OPC	adcs

# define RETC	mov r0, #0; adc r0, r0, r0

# define FUNC	__mpn_add_n

#endif

/* mp_limb_t mpn_add_n(res_ptr, src1_ptr, src2_ptr, size) */

ENTRY (FUNC)

	push	{ r4, r5, r6, r7, r8, r10, lr }

	cfi_adjust_cfa_offset (28)

	cfi_rel_offset (r4, 0)

	cfi_rel_offset (r5, 4)

	cfi_rel_offset (r6, 8)

	cfi_rel_offset (r7, 12)

	cfi_rel_offset (r8, 16)

	cfi_rel_offset (r10, 20)

	cfi_rel_offset (lr, 24)

	INITC				/* initialize carry flag */

	tst	r3, #1			/* count & 1 == 1? */

	add	lr, r1, r3, lsl #2	/* compute end src1 */

	beq	1f

	ldr	r4, [r1], #4		/* do one to make count even */

	ldr	r5, [r2], #4

	OPC	r4, r4, r5

	teq	r1, lr			/* end of count? (preserve carry) */

	str	r4, [r0], #4

	beq	9f

1:

	tst	r3, #2			/* count & 2 == 2?  */

	beq	2f

	ldm	r1!, { r4, r5 }		/* do two to make count 0 mod 4 */

	ldm	r2!, { r6, r7 }

	OPC	r4, r4, r6

	OPC	r5, r5, r7

	teq	r1, lr			/* end of count? */

	stm	r0!, { r4, r5 }

	beq	9f

2:

	ldm	r1!, { r3, r5, r7, r10 }	/* do four each loop */

	ldm	r2!, { r4, r6, r8, ip }

	OPC	r3, r3, r4

	OPC	r5, r5, r6

	OPC	r7, r7, r8

	OPC	r10, r10, ip

	teq	r1, lr

	stm	r0!, { r3, r5, r7, r10 }

	bne	2b

9:

	RETC				/* copy carry out */

#ifndef ARM_ALWAYS_BX

	pop	{ r4, r5, r6, r7, r8, r10, pc }

#else

	pop	{ r4, r5, r6, r7, r8, r10, lr }

	bx	lr

#endif

END (FUNC)