1204 /* P = (x1, y1) => 2P, (x2, y2) => P' */
1205 static void xycz_initial_double(u64 *x1, u64 *y1, u64 *x2, u64 *y2,  in xycz_initial_double()  argument
1212 	vli_set(y2, y1, ndigits);  in xycz_initial_double()
1224 	apply_z(x2, y2, z, curve);  in xycz_initial_double()
1227 /* Input P = (x1, y1, Z), Q = (x2, y2, Z)
1231 static void xycz_add(u64 *x1, u64 *y1, u64 *x2, u64 *y2,  in xycz_add()  argument
1234 	/* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */  in xycz_add()
1247 	/* t4 = y2 - y1 */  in xycz_add()
1248 	vli_mod_sub(y2, y2, y1, curve_prime, ndigits);  in xycz_add()
1249 	/* t5 = (y2 - y1)^2 = D */  in xycz_add()
1250 	vli_mod_square_fast(t5, y2, curve);  in xycz_add()
1262 	/* t4 = (y2 - y1)*(B - x3) */  in xycz_add()
1263 	vli_mod_mult_fast(y2, y2, x2, curve);  in xycz_add()
1265 	vli_mod_sub(y2, y2, y1, curve_prime, ndigits);  in xycz_add()
1270 /* Input P = (x1, y1, Z), Q = (x2, y2, Z)
1274 static void xycz_add_c(u64 *x1, u64 *y1, u64 *x2, u64 *y2,  in xycz_add_c()  argument
1277 	/* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */  in xycz_add_c()
1292 	/* t4 = y2 + y1 */  in xycz_add_c()
1293 	vli_mod_add(t5, y2, y1, curve_prime, ndigits);  in xycz_add_c()
1294 	/* t4 = y2 - y1 */  in xycz_add_c()
1295 	vli_mod_sub(y2, y2, y1, curve_prime, ndigits);  in xycz_add_c()
1303 	/* t3 = (y2 - y1)^2 */  in xycz_add_c()
1304 	vli_mod_square_fast(x2, y2, curve);  in xycz_add_c()
1310 	/* t4 = (y2 - y1)*(B - x3) */  in xycz_add_c()
1311 	vli_mod_mult_fast(y2, y2, t7, curve);  in xycz_add_c()
1313 	vli_mod_sub(y2, y2, y1, curve_prime, ndigits);  in xycz_add_c()
1315 	/* t7 = (y2 + y1)^2 = F */  in xycz_add_c()
1321 	/* t6 = (y2 + y1)*(x3' - B) */  in xycz_add_c()