1155 /* P = (x1, y1) => 2P, (x2, y2) => P' */
1156 static void xycz_initial_double(u64 *x1, u64 *y1, u64 *x2, u64 *y2,  in xycz_initial_double()  argument
1163 	vli_set(y2, y1, ndigits);  in xycz_initial_double()
1175 	apply_z(x2, y2, z, curve);  in xycz_initial_double()
1178 /* Input P = (x1, y1, Z), Q = (x2, y2, Z)
1182 static void xycz_add(u64 *x1, u64 *y1, u64 *x2, u64 *y2,  in xycz_add()  argument
1185 	/* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */  in xycz_add()
1198 	/* t4 = y2 - y1 */  in xycz_add()
1199 	vli_mod_sub(y2, y2, y1, curve_prime, ndigits);  in xycz_add()
1200 	/* t5 = (y2 - y1)^2 = D */  in xycz_add()
1201 	vli_mod_square_fast(t5, y2, curve);  in xycz_add()
1213 	/* t4 = (y2 - y1)*(B - x3) */  in xycz_add()
1214 	vli_mod_mult_fast(y2, y2, x2, curve);  in xycz_add()
1216 	vli_mod_sub(y2, y2, y1, curve_prime, ndigits);  in xycz_add()
1221 /* Input P = (x1, y1, Z), Q = (x2, y2, Z)
1225 static void xycz_add_c(u64 *x1, u64 *y1, u64 *x2, u64 *y2,  in xycz_add_c()  argument
1228 	/* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */  in xycz_add_c()
1243 	/* t4 = y2 + y1 */  in xycz_add_c()
1244 	vli_mod_add(t5, y2, y1, curve_prime, ndigits);  in xycz_add_c()
1245 	/* t4 = y2 - y1 */  in xycz_add_c()
1246 	vli_mod_sub(y2, y2, y1, curve_prime, ndigits);  in xycz_add_c()
1254 	/* t3 = (y2 - y1)^2 */  in xycz_add_c()
1255 	vli_mod_square_fast(x2, y2, curve);  in xycz_add_c()
1261 	/* t4 = (y2 - y1)*(B - x3) */  in xycz_add_c()
1262 	vli_mod_mult_fast(y2, y2, t7, curve);  in xycz_add_c()
1264 	vli_mod_sub(y2, y2, y1, curve_prime, ndigits);  in xycz_add_c()
1266 	/* t7 = (y2 + y1)^2 = F */  in xycz_add_c()
1272 	/* t6 = (y2 + y1)*(x3' - B) */  in xycz_add_c()