ARM assembly for ecc_521_modp.

ChangeLog

+2013-03-05  Niels Möller  <nisse@lysator.liu.se>
+
+	* configure.ac (asm_optional_list): Added ecc-521-modp.asm.
+	* ecc-521.c: Check HAVE_NATIVE_ecc_521_modp, and use native
+	version if available.
+	* armv7/ecc-521-modp.asm: New file, 2 time speedup over C version.
+
 2013-03-04  Niels Möller  <nisse@lysator.liu.se>
 
 	* configure.ac (asm_optional_list): Added ecc-384-modp.asm. Deleted
 	bogus reference to $asm_search_list.
-
 	* ecc-384.c: Check HAVE_NATIVE_ecc_384_modp, and use native
 	version if available.
 	* armv7/ecc-384-modp.asm: New file, 3 time speedup over C version.

armv7/ecc-521-modp.asm

+C nettle, low-level cryptographics library
+C
+C Copyright (C) 2013, Niels Möller
+C
+C The nettle library is free software; you can redistribute it and/or modify
+C it under the terms of the GNU Lesser General Public License as published by
+C the Free Software Foundation; either version 2.1 of the License, or (at your
+C option) any later version.
+C
+C The nettle library is distributed in the hope that it will be useful, but
+C WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+C or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
+C License for more details.
+C
+C You should have received a copy of the GNU Lesser General Public License
+C along with the nettle library; see the file COPYING.LIB.  If not, write to
+C the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+C MA 02111-1301, USA.
+
+	.file "ecc-521-modp.asm"
+	.arm
+
+define(<HP>, <r0>)
+define(<RP>, <r1>)
+define(<T0>, <r2>)
+define(<T1>, <r3>)
+define(<T2>, <r4>)
+define(<F0>, <r5>)
+define(<F1>, <r6>)
+define(<F2>, <r7>)
+define(<F3>, <r8>)
+define(<H>, <r12>)
+define(<N>, <lr>)
+
+	C ecc_521_modp (const struct ecc_curve *ecc, mp_limb_t *rp)
+	.text
+.Lc511:
+	.int 511
+
+	.align 2
+
+PROLOGUE(nettle_ecc_521_modp)
+	push	{r4,r5,r6,r7,r8,lr}
+
+	C Use that B^17 = 2^23 (mod p)
+	ldr	F3, [RP, #+68]		C 17
+	add	HP, RP, #72		C 18
+	ldr	T0, [RP]		C 0
+	adds	T0, T0, F3, lsl	#23
+	str	T0, [RP], #+4
+	mov	N, #5
+
+	C 5 iterations, reading limbs 18-20, 21-23, 24-26, 27-29, 30-32
+	C and adding to limbs          1-3,    4-6,   7-9, 19-12, 13-15
+.Loop:
+	ldm	RP, {T0,T1,T2}		C  1+3*k --  3+3*k
+	lsr	F0, F3, #9
+	ldm	HP!, {F1,F2,F3}		C 18+3*k -- 20+3*k
+	orr	F0, F0, F1, lsl #23
+	lsr	F1, F1, #9
+	orr	F1, F1, F2, lsl #23
+	lsr	F2, F2, #9
+	orr	F2, F2, F3, lsl #23
+	adcs	T0, T0, F0
+	adcs	T1, T1, F1
+	adcs	T2, T2, F2
+	sub	N, N, #1
+	stm	RP!,{T0,T1,T2}
+	teq	N, #0
+	bne	.Loop
+
+	ldr	F0, [RP], #-64		C 16
+	ldr	F1, [HP]		C 33
+	ldr	T0, .Lc511
+
+	C Handling of high limbs
+	C F0 = rp[16] + carry in + F3 >> 9
+	adcs	F0, F0, F3, lsr #9
+	C Copy low 9 bits to H, then shift right including carry
+	and	H, F0, T0
+	rrx	F0, F0
+	lsr	F0, F0, #8
+	C Add in F1 = rp[33], with weight 2^1056 = 2^14
+	adds	F0, F0, F1, lsl #14
+	lsr	F1, F1, #18
+	adc	F1, F1, #0
+
+	ldm	RP, {T0, T1}		C 0-1
+	adds	T0, T0, F0
+	adcs	T1, T1, F1
+	stm	RP!, {T0, T1}
+
+	ldm	RP, {T0,T1,T2,F0,F1,F2,F3}	C 2-8
+	adcs	T0, T0, #0
+	adcs	T1, T1, #0
+	adcs	T2, T2, #0
+	adcs	F0, F0, #0
+	adcs	F1, F1, #0
+	adcs	F2, F2, #0
+	adcs	F3, F3, #0
+	stm	RP!, {T0,T1,T2,F0,F1,F2,F3}	C 2-8
+	ldm	RP, {T0,T1,T2,F0,F1,F2,F3}	C 9-15
+	adcs	T0, T0, #0
+	adcs	T1, T1, #0
+	adcs	T2, T2, #0
+	adcs	F0, F0, #0
+	adcs	F1, F1, #0
+	adcs	F2, F2, #0
+	adcs	F3, F3, #0
+	adcs	H, H, #0
+	stm	RP, {T0,T1,T2,F0,F1,F2,F3,H}	C 9-16
+
+	pop	{r4,r5,r6,r7,r8,pc}
+EPILOGUE(nettle_ecc_521_modp)

configure.ac

@@ -250,7 +250,8 @@ asm_replace_list="aes-encrypt-internal.asm aes-decrypt-internal.asm \
 asm_optional_list=""
 
 if test "x$enable_public_key" = "xyes" ; then
-  asm_optional_list="ecc-192-modp.asm ecc-224-modp.asm ecc-256-redc.asm ecc-384-modp.asm"
+  asm_optional_list="ecc-192-modp.asm ecc-224-modp.asm ecc-256-redc.asm \
+      ecc-384-modp.asm ecc-521-modp.asm"
 fi
 
 OPT_ASM_SOURCES=""

ecc-521.c

@@ -34,6 +34,13 @@
 
 #include "ecc-521.h"
 
+#if HAVE_NATIVE_ecc_521_modp
+#define ecc_521_modp nettle_ecc_521_modp
+void
+ecc_521_modp (const struct ecc_curve *ecc, mp_limb_t *rp);
+
+#else
+
 #define B_SHIFT (521 % GMP_NUMB_BITS)
 #define BMODP_SHIFT (GMP_NUMB_BITS - B_SHIFT)
 #define BMODP ((mp_limb_t) 1 << BMODP_SHIFT)
@@ -56,6 +63,7 @@ ecc_521_modp (const struct ecc_curve *ecc UNUSED, mp_limb_t *rp)
 			 & (((mp_limb_t) 1 << B_SHIFT)-1))
     + sec_add_1 (rp, rp, ECC_LIMB_SIZE - 1, hi);
 }
+#endif
 
 const struct ecc_curve nettle_secp_521r1 =
 {