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tls: P256: simplify sp_256_mont_inv_8 (no need for a temporary)

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function                                             old     new   delta
sp_256_ecc_mulmod_8                                  543     517     -26

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-11-28 11:10:00 +01:00
parent bfefa6ab6c
commit cfb615781d
1 changed files with 4 additions and 6 deletions
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10
networking/tls_sp_c32.c
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@ -938,7 +938,7 @@ static void sp_256_mont_sqr_8(sp_digit* r, const sp_digit* a
/* Invert the number, in Montgomery form, modulo the modulus (prime) of the
* P256 curve. (r = 1 / a mod m)
*
* r Inverse result.
* r Inverse result. Must not coincide with a.
* a Number to invert.
*/
#if 0
@ -952,17 +952,15 @@ static void sp_256_mont_sqr_8(sp_digit* r, const sp_digit* a
#endif
static void sp_256_mont_inv_8(sp_digit* r, sp_digit* a)
{
sp_digit t[8];
int i;
memcpy(t, a, sizeof(sp_digit) * 8);
memcpy(r, a, sizeof(sp_digit) * 8);
for (i = 254; i >= 0; i--) {
sp_256_mont_sqr_8(t, t /*, p256_mod, p256_mp_mod*/);
sp_256_mont_sqr_8(r, r /*, p256_mod, p256_mp_mod*/);
/*if (p256_mod_2[i / 32] & ((sp_digit)1 << (i % 32)))*/
if (i >= 224 || i == 192 || (i <= 95 && i != 1))
sp_256_mont_mul_8(t, t, a /*, p256_mod, p256_mp_mod*/);
sp_256_mont_mul_8(r, r, a /*, p256_mod, p256_mp_mod*/);
}
memcpy(r, t, sizeof(sp_digit) * 8);
}
/* Multiply a number by Montogmery normalizer mod modulus (prime).