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Start splitting precompute_comb()

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This is the easy part: with the current steps, all information between steps
is passed via T which is already saved. Next we'll need to split at least the
first loop, and maybe calls to normalize_jac_many() and/or the second loop.
This commit is contained in:
Manuel Pégourié-Gonnard 2017-03-20 10:24:17 +01:00
parent 67c83fb871
commit e2d7cb3f10
1 changed files with 45 additions and 5 deletions
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50
library/ecp.c
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@ -113,7 +113,9 @@ struct mbedtls_ecp_restart {
unsigned char T_size; /* number of points in table T */
enum { /* what's the next step ? */
ecp_rs_init = 0, /* just getting started */
ecp_rs_tmp_dummy, /* temporary for incremental testing */
ecp_rs_pre_norm_dbl, /* normalize precomputed 2^n multiples */
ecp_rs_pre_add, /* precompute remaining points by adding */
ecp_rs_pre_norm_add, /* normalize all precomputed points */
ecp_rs_T_done, /* call ecp_mul_comb_after_precomp() */
ecp_rs_final_norm, /* do the final normalization */
} state;
@ -1338,11 +1340,14 @@ static int ecp_precompute_comb( const mbedtls_ecp_group *grp,
mbedtls_ecp_point *cur, *TT[COMB_MAX_PRE - 1];
#if defined(MBEDTLS_ECP_EARLY_RETURN)
/* XXX: dummy "in_progress" return for testing caller */
if( grp->rs != NULL && grp->rs->state == ecp_rs_init )
if( grp->rs != NULL )
{
grp->rs->state++;
return( MBEDTLS_ERR_ECP_IN_PROGRESS );
if( grp->rs->state == ecp_rs_pre_norm_add )
goto norm_add;
if( grp->rs->state == ecp_rs_pre_add )
goto add;
if( grp->rs->state == ecp_rs_pre_norm_dbl )
goto norm_dbl;
}
#endif
@ -1350,6 +1355,8 @@ static int ecp_precompute_comb( const mbedtls_ecp_group *grp,
* Set T[0] = P and
* T[2^{l-1}] = 2^{dl} P for l = 1 .. w-1 (this is not the final value)
*/
ECP_BUDGET( ( w - 1 ) * d * ECP_OPS_DBL ); // XXX: split loop
MBEDTLS_MPI_CHK( mbedtls_ecp_copy( &T[0], P ) );
for( i = 1; i < T_len; i <<= 1 )
@ -1360,20 +1367,42 @@ static int ecp_precompute_comb( const mbedtls_ecp_group *grp,
MBEDTLS_MPI_CHK( ecp_double_jac( grp, cur, cur ) );
}
#if defined(MBEDTLS_ECP_EARLY_RETURN)
if( grp->rs != NULL )
grp->rs->state++;
#endif
/*
* Normalize current elements in T. As T has holes,
* use an auxiliary array of pointers to elements in T.
*/
#if defined(MBEDTLS_ECP_EARLY_RETURN)
norm_dbl:
#endif
j = 0;
for( i = 1; i < T_len; i <<= 1 )
TT[j++] = T + i;
ECP_BUDGET( ECP_OPS_INV + 6 * j - 2 ); // XXX: split next function?
MBEDTLS_MPI_CHK( ecp_normalize_jac_many( grp, TT, j ) );
#if defined(MBEDTLS_ECP_EARLY_RETURN)
if( grp->rs != NULL )
grp->rs->state++;
#endif
/*
* Compute the remaining ones using the minimal number of additions
* Be careful to update T[2^l] only after using it!
*/
#if defined(MBEDTLS_ECP_EARLY_RETURN)
add:
#endif
ECP_BUDGET( ( T_len - 1 ) * ECP_OPS_ADD ); // XXX: split loop?
for( i = 1; i < T_len; i <<= 1 )
{
j = i;
@ -1381,14 +1410,25 @@ static int ecp_precompute_comb( const mbedtls_ecp_group *grp,
MBEDTLS_MPI_CHK( ecp_add_mixed( grp, &T[i + j], &T[j], &T[i] ) );
}
#if defined(MBEDTLS_ECP_EARLY_RETURN)
if( grp->rs != NULL )
grp->rs->state++;
#endif
/*
* Normalize final elements in T. Even though there are no holes now,
* we still need the auxiliary array for homogeneity with last time.
* Also, skip T[0] which is already normalised, being a copy of P.
*/
#if defined(MBEDTLS_ECP_EARLY_RETURN)
norm_add:
#endif
for( j = 0; j + 1 < T_len; j++ )
TT[j] = T + j + 1;
ECP_BUDGET( ECP_OPS_INV + 6 * j - 2 ); // XXX: split next function?
MBEDTLS_MPI_CHK( ecp_normalize_jac_many( grp, TT, j ) );
#if defined(MBEDTLS_ECP_EARLY_RETURN)