C x86_64/ecc-224-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-224-modp.asm"

GMP_NUMB_BITS(64)

define(<RP>, <%rsi>)
define(<T0>, <%rdi>) C Overlaps unused modulo input
define(<T1>, <%rcx>)
define(<H0>, <%rax>)
define(<H1>, <%rdx>)
define(<H2>, <%r8>)
define(<F0>, <%r9>)
define(<F1>, <%r10>)
define(<F2>, <%r11>)

	C ecc_224_modp (const struct ecc_modulo *m, mp_limb_t *rp)
PROLOGUE(nettle_ecc_224_modp)
	W64_ENTRY(2, 0)
	mov	48(RP), H0
	mov	56(RP), H1
	C Set (F2,F1,F0)  <--  (H1,H0) << 32
	mov	H0, F0
	mov	H0, F1
	shl	$32, F0
	shr	$32, F1
	mov	H1, F2
	mov	H1, T0
	shl	$32, T0
	shr	$32, F2
	or	T0, F1

	xor	H2, H2
	mov	16(RP), T0
	mov	24(RP), T1
	sub	F0, T0
	sbb	F1, T1
	sbb	F2, H0
	sbb	$0, H1		C No further borrow

	adc	32(RP), H0
	adc	40(RP), H1
	adc	$0, H2

	C Set (F2,F1,F0)  <--  (H2,H1,H0) << 32
	C To free registers, add in T1, T0 as soon as H0, H1 have been copied
	mov	H0, F0
	mov	H0, F1
	add	T0, H0
	mov	H1, F2
	mov	H1, T0
	adc	T1, H1
	mov	H2, T1
	adc	$0, H2

	C Shift 32 bits
	shl	$32, F0
	shr	$32, F1
	shl	$32, T0
	shr	$32, F2
	shl	$32, T1
	or	T0, F1
	or	T1, F2

	mov	(RP), T0
	mov	8(RP), T1
	sub	F0, T0
	sbb	F1, T1
	sbb	F2, H0
	sbb	$0, H1
	sbb	$0, H2

	C We now have H2, H1, H0, T1, T0, with 33 bits left to reduce
	C Set F0       <-- (H2, H1) >> 32
	C Set (F2,F1)  <-- (H2, H1 & 0xffffffff00000000)
	C H1  <--  H1 & 0xffffffff

	mov	H1, F0
	mov	H1, F1
	mov	H2, F2
	movl	XREG(H1), XREG(H1)	C Clears high 32 bits
	sub	H1, F1			C Clears low 32 bits
	shr	$32, F0
	shl	$32, H2
	or	H2, F0

	sub	F0, T0
	sbb	$0, F1
	sbb	$0, F2
	add	F1, T1
	adc	F2, H0
	adc	$0, H1

	mov	T0, (RP)
	mov	T1, 8(RP)
	mov	H0, 16(RP)
	mov	H1, 24(RP)

	W64_EXIT(2, 0)
	ret
EPILOGUE(nettle_ecc_224_modp)