static void ep2_mul_sim_plain(ep2_t r, ep2_t p, bn_t k, ep2_t q, bn_t l,
ep2_t *t) {
int len, l0, l1, i, n0, n1, w, gen;
int8_t naf0[2 * FP_BITS + 1], naf1[2 * FP_BITS + 1], *_k, *_m;
ep2_t t0[1 << (EP_WIDTH - 2)];
ep2_t t1[1 << (EP_WIDTH - 2)];
for (i = 0; i < (1 << (EP_WIDTH - 2)); i++) {
ep2_null(t0[i]);
ep2_null(t1[i]);
}
TRY {
gen = (t == NULL ? 0 : 1);
if (!gen) {
for (i = 0; i < (1 << (EP_WIDTH - 2)); i++) {
ep2_new(t0[i]);
}
ep2_tab(t0, p, EP_WIDTH);
t = (ep2_t *)t0;
}
/* Prepare the precomputation table. */
for (i = 0; i < (1 << (EP_WIDTH - 2)); i++) {
ep2_new(t1[i]);
}
/* Compute the precomputation table. */
ep2_tab(t1, q, EP_WIDTH);
/* Compute the w-TNAF representation of k. */
if (gen) {
w = EP_DEPTH;
} else {
w = EP_WIDTH;
}
l0 = l1 = 2 * FP_BITS + 1;
bn_rec_naf(naf0, &l0, k, w);
bn_rec_naf(naf1, &l1, l, EP_WIDTH);
len = MAX(l0, l1);
_k = naf0 + len - 1;
_m = naf1 + len - 1;
for (i = l0; i < len; i++)
naf0[i] = 0;
for (i = l1; i < len; i++)
naf1[i] = 0;
ep2_set_infty(r);
for (i = len - 1; i >= 0; i--, _k--, _m--) {
ep2_dbl(r, r);
n0 = *_k;
n1 = *_m;
if (n0 > 0) {
ep2_add(r, r, t[n0 / 2]);
}
if (n0 < 0) {
ep2_sub(r, r, t[-n0 / 2]);
}
if (n1 > 0) {
ep2_add(r, r, t1[n1 / 2]);
}
if (n1 < 0) {
ep2_sub(r, r, t1[-n1 / 2]);
}
}
/* Convert r to affine coordinates. */
ep2_norm(r, r);
}
CATCH_ANY {
THROW(ERR_CAUGHT);
}
FINALLY {
/* Free the precomputation tables. */
if (!gen) {
for (i = 0; i < (1 << (EP_WIDTH - 2)); i++) {
ep2_free(t0[i]);
}
}
for (i = 0; i < (1 << (EP_WIDTH - 2)); i++) {
ep2_free(t1[i]);
}
}
}
static void ep2_mul_sim_ordin(ep2_t r, ep2_t p, bn_t k, ep2_t q, bn_t l, int gen) {
int len, l0, l1, i, n0, n1, w;
signed char naf0[FP_BITS + 1], naf1[FP_BITS + 1], *t0, *t1;
ep2_t table0[1 << (EP_WIDTH - 2)];
ep2_t table1[1 << (EP_WIDTH - 2)];
ep2_t *t = NULL;
for (i = 0; i < (1 << (EP_WIDTH - 2)); i++) {
ep2_null(table0[i]);
ep2_null(table1[i]);
}
if (gen) {
#if defined(EP_PRECO)
t = ep2_curve_get_tab();
#endif
} else {
for (i = 0; i < (1 << (EP_WIDTH - 2)); i++) {
ep2_new(table0[i]);
}
ep2_tab(table0, p, EP_WIDTH);
t = table0;
}
/* Prepare the precomputation table. */
for (i = 0; i < (1 << (EP_WIDTH - 2)); i++) {
ep2_new(table1[i]);
}
/* Compute the precomputation table. */
ep2_tab(table1, q, EP_WIDTH);
/* Compute the w-TNAF representation of k. */
if (gen) {
w = EP_DEPTH;
} else {
w = EP_WIDTH;
}
l0 = l1 = FP_BITS + 1;
bn_rec_naf(naf0, &l0, k, w);
bn_rec_naf(naf1, &l1, l, EP_WIDTH);
len = MAX(l0, l1);
t0 = naf0 + len - 1;
t1 = naf1 + len - 1;
for (i = l0; i < len; i++)
naf0[i] = 0;
for (i = l1; i < len; i++)
naf1[i] = 0;
ep2_set_infty(r);
for (i = len - 1; i >= 0; i--, t0--, t1--) {
ep2_dbl(r, r);
n0 = *t0;
n1 = *t1;
if (n0 > 0) {
ep2_add(r, r, t[n0 / 2]);
}
if (n0 < 0) {
ep2_sub(r, r, t[-n0 / 2]);
}
if (n1 > 0) {
ep2_add(r, r, table1[n1 / 2]);
}
if (n1 < 0) {
ep2_sub(r, r, table1[-n1 / 2]);
}
}
/* Convert r to affine coordinates. */
ep2_norm(r, r);
/* Free the precomputation table. */
for (i = 0; i < 1 << (EP_WIDTH - 2); i++) {
ep2_free(table0[i]);
ep2_free(table1[i]);
}
}
