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ecmult_impl: save one fe_inv_var

This commit is contained in:
Andrew Poelstra 2018-10-01 21:00:41 +00:00
parent 47045270fa
commit 84740acd2a
1 changed files with 2 additions and 1 deletions
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3
src/ecmult_impl.h
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@ -183,6 +183,7 @@ static void secp256k1_ecmult_odd_multiples_table_storage_var(const int n, secp25
}
/* Map `pj` back to our curve by multiplying its z-coordinate by `d.z`. */
zr = pj.z; /* save pj.z so we can use it to extract (d.z)^-1 from zi */
secp256k1_fe_mul(&pj.z, &pj.z, &d.z);
/* Directly set `pre[n - 1]` to `pj`, saving the inverted z-coordinate so
* that we can combine it with the saved z-ratios to compute the other zs
@ -193,7 +194,7 @@ static void secp256k1_ecmult_odd_multiples_table_storage_var(const int n, secp25
secp256k1_ge_to_storage(&pre[n - 1], &p_ge);
/* Compute the actual x-coordinate of D, which will be needed below. */
secp256k1_fe_inv_var(&d.z, &d.z);
secp256k1_fe_mul(&d.z, &zi, &zr); /* d.z = 1/d.z */
secp256k1_fe_sqr(&dx_over_dz_squared, &d.z);
secp256k1_fe_mul(&dx_over_dz_squared, &dx_over_dz_squared, &d.x);