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libsecp256k1/src/group_impl.h  view on Meta::CPAN

    secp256k1_fe_set_int(&a->z, 1);
    secp256k1_ge_set_xy(r, &a->x, &a->y);

    SECP256K1_GEJ_VERIFY(a);
    SECP256K1_GE_VERIFY(r);
}

static void secp256k1_ge_set_all_gej_var(secp256k1_ge *r, const secp256k1_gej *a, size_t len) {
    secp256k1_fe u;
    size_t i;
    size_t last_i = SIZE_MAX;
#ifdef VERIFY
    for (i = 0; i < len; i++) {
        SECP256K1_GEJ_VERIFY(&a[i]);
    }
#endif

    for (i = 0; i < len; i++) {
        if (a[i].infinity) {
            secp256k1_ge_set_infinity(&r[i]);
        } else {
            /* Use destination's x coordinates as scratch space */
            if (last_i == SIZE_MAX) {
                r[i].x = a[i].z;
            } else {
                secp256k1_fe_mul(&r[i].x, &r[last_i].x, &a[i].z);
            }
            last_i = i;
        }
    }
    if (last_i == SIZE_MAX) {
        return;
    }
    secp256k1_fe_inv_var(&u, &r[last_i].x);

    i = last_i;
    while (i > 0) {
        i--;
        if (!a[i].infinity) {
            secp256k1_fe_mul(&r[last_i].x, &r[i].x, &u);
            secp256k1_fe_mul(&u, &u, &a[last_i].z);
            last_i = i;
        }
    }
    VERIFY_CHECK(!a[last_i].infinity);
    r[last_i].x = u;

    for (i = 0; i < len; i++) {
        if (!a[i].infinity) {
            secp256k1_ge_set_gej_zinv(&r[i], &a[i], &r[i].x);
        }
    }

#ifdef VERIFY
    for (i = 0; i < len; i++) {
        SECP256K1_GE_VERIFY(&r[i]);
    }
#endif
}

static void secp256k1_ge_table_set_globalz(size_t len, secp256k1_ge *a, const secp256k1_fe *zr) {
    size_t i;
    secp256k1_fe zs;
#ifdef VERIFY
    for (i = 0; i < len; i++) {
        SECP256K1_GE_VERIFY(&a[i]);
        SECP256K1_FE_VERIFY(&zr[i]);
    }
#endif

    if (len > 0) {
        i = len - 1;
        /* Ensure all y values are in weak normal form for fast negation of points */
        secp256k1_fe_normalize_weak(&a[i].y);
        zs = zr[i];

        /* Work our way backwards, using the z-ratios to scale the x/y values. */
        while (i > 0) {
            if (i != len - 1) {
                secp256k1_fe_mul(&zs, &zs, &zr[i]);
            }
            i--;
            secp256k1_ge_set_ge_zinv(&a[i], &a[i], &zs);
        }
    }

#ifdef VERIFY
    for (i = 0; i < len; i++) {
        SECP256K1_GE_VERIFY(&a[i]);
    }
#endif
}

static void secp256k1_gej_set_infinity(secp256k1_gej *r) {
    r->infinity = 1;
    secp256k1_fe_set_int(&r->x, 0);
    secp256k1_fe_set_int(&r->y, 0);
    secp256k1_fe_set_int(&r->z, 0);

    SECP256K1_GEJ_VERIFY(r);
}

static void secp256k1_ge_set_infinity(secp256k1_ge *r) {
    r->infinity = 1;
    secp256k1_fe_set_int(&r->x, 0);
    secp256k1_fe_set_int(&r->y, 0);

    SECP256K1_GE_VERIFY(r);
}

static void secp256k1_gej_clear(secp256k1_gej *r) {
    secp256k1_memclear(r, sizeof(secp256k1_gej));
}

static void secp256k1_ge_clear(secp256k1_ge *r) {
    secp256k1_memclear(r, sizeof(secp256k1_ge));
}

static int secp256k1_ge_set_xo_var(secp256k1_ge *r, const secp256k1_fe *x, int odd) {
    secp256k1_fe x2, x3;
    int ret;