- dccp_timestamp(sk, &now);
- if (timeval_delta(&now, &hctx->ccid3hctx_t_ld) >=
- hctx->ccid3hctx_rtt) {
- hctx->ccid3hctx_x = max_t(u32, min_t(u32, hctx->ccid3hctx_x_recv,
- hctx->ccid3hctx_x) * 2,
- usecs_div(hctx->ccid3hctx_s,
- hctx->ccid3hctx_rtt));
- hctx->ccid3hctx_t_ld = now;
- }
+ hctx->ccid3hctx_x = min(((__u64)hctx->ccid3hctx_x_calc) << 6,
+ hctx->ccid3hctx_x_recv * 2);
+ hctx->ccid3hctx_x = max(hctx->ccid3hctx_x,
+ (((__u64)hctx->ccid3hctx_s) << 6) /
+ TFRC_T_MBI);
+
+ } else if (timeval_delta(now, &hctx->ccid3hctx_t_ld) -
+ (suseconds_t)hctx->ccid3hctx_rtt >= 0) {
+
+ hctx->ccid3hctx_x =
+ max(2 * min(hctx->ccid3hctx_x, hctx->ccid3hctx_x_recv),
+ scaled_div(((__u64)hctx->ccid3hctx_s) << 6,
+ hctx->ccid3hctx_rtt));
+ hctx->ccid3hctx_t_ld = *now;
+ }
+
+ if (hctx->ccid3hctx_x != old_x)
+ ccid3_update_send_time(hctx);
+}
+
+/*
+ * Track the mean packet size `s' (cf. RFC 4342, 5.3 and RFC 3448, 4.1)
+ * @len: DCCP packet payload size in bytes
+ */
+static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hctx, int len)
+{
+ if (unlikely(len == 0))
+ ccid3_pr_debug("Packet payload length is 0 - not updating\n");
+ else
+ hctx->ccid3hctx_s = hctx->ccid3hctx_s == 0 ? len :
+ (9 * hctx->ccid3hctx_s + len) / 10;
+ /*
+ * Note: We could do a potential optimisation here - when `s' changes,
+ * recalculate sending rate and consequently t_ipi, t_delta, and
+ * t_now. This is however non-standard, and the benefits are not
+ * clear, so it is currently left out.
+ */
+}
+
+/*
+ * Update Window Counter using the algorithm from [RFC 4342, 8.1].
+ * The algorithm is not applicable if RTT < 4 microseconds.
+ */
+static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx,
+ struct timeval *now)
+{
+ suseconds_t delta;
+ u32 quarter_rtts;
+
+ if (unlikely(hctx->ccid3hctx_rtt < 4)) /* avoid divide-by-zero */
+ return;
+
+ delta = timeval_delta(now, &hctx->ccid3hctx_t_last_win_count);
+ DCCP_BUG_ON(delta < 0);
+
+ quarter_rtts = (u32)delta / (hctx->ccid3hctx_rtt / 4);
+
+ if (quarter_rtts > 0) {
+ hctx->ccid3hctx_t_last_win_count = *now;
+ hctx->ccid3hctx_last_win_count += min_t(u32, quarter_rtts, 5);
+ hctx->ccid3hctx_last_win_count &= 0xF; /* mod 16 */
+
+ ccid3_pr_debug("now at %#X\n", hctx->ccid3hctx_last_win_count);