C arm/ecc-192-modp.asm

ifelse(<
   Copyright (C) 2013 Niels Möller

   This file is part of GNU Nettle.

   GNU Nettle is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.

   GNU Nettle 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
   General Public License for more details.

   You should have received copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see http://www.gnu.org/licenses/.
>) 

	.file "ecc-192-modp.asm"
	.arm

define(<HP>, <r0>) C Overlaps unused modulo argument
define(<RP>, <r1>)

define(<T0>, <r2>)
define(<T1>, <r3>)
define(<T2>, <r4>)
define(<T3>, <r5>)
define(<T4>, <r6>)
define(<T5>, <r7>)
define(<T6>, <r8>)
define(<T7>, <r10>)
define(<H0>, <T0>) C Overlaps T0 and T1
define(<H1>, <T1>)
define(<C2>, <HP>)
define(<C4>, <r12>)

	C ecc_192_modp (const struct ecc_modulo *m, mp_limb_t *rp)
	.text
	.align 2

PROLOGUE(nettle_ecc_192_modp)
	push	{r4,r5,r6,r7,r8,r10}
	C Reduce two words at a time
	add	HP, RP, #48
	add	RP, RP, #8
	ldmdb	HP!, {H0,H1}
	ldm	RP, {T2,T3,T4,T5,T6,T7}
	mov	C4, #0
	adds	T4, T4, H0
	adcs	T5, T5, H1
	adcs	T6, T6, H0
	adcs	T7, T7, H1
	C Need to add carry to T2 and T4, do T4 later.
	adc	C4, C4, #0

	ldmdb	HP!, {H0,H1}
	mov	C2, #0
	adcs	T2, T2, H0
	adcs	T3, T3, H1
	adcs	T4, T4, H0
	adcs	T5, T5, H1
	C Need to add carry to T0 and T2, do T2 later
	adc	C2, C2, #0

	ldmdb	RP!, {T0, T1}
	adcs	T0, T0, T6
	adcs	T1, T1, T7
	adcs	T2, T2, T6
	adcs	T3, T3, T7
	adc	C4, C4, #0

	adds	T2, T2, C2
	adcs	T3, T3, #0
	adcs	T4, T4, C4
	adcs	T5, T5, #0
	mov	C2, #0
	adc	C2, C2, #0

	C Add in final carry
	adcs	T0, T0, #0
	adcs	T1, T1, #0
	adcs	T2, T2, C2
	adcs	T3, T3, #0
	adcs	T4, T4, #0
	adc	T5, T5, #0

	stm	RP, {T0,T1,T2,T3,T4,T5}

	pop	{r4,r5,r6,r7,r8,r10}
	bx	lr
EPILOGUE(nettle_ecc_192_modp)