139 lines
3.7 KiB
C
139 lines
3.7 KiB
C
/*
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* Copyright (c) 2020 Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/net/net_timeout.h>
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#include <zephyr/sys_clock.h>
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void net_timeout_set(struct net_timeout *timeout,
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uint32_t lifetime,
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uint32_t now)
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{
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uint64_t expire_timeout;
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timeout->timer_start = now;
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/* Highly unlikely, but a zero timeout isn't correctly handled by the
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* standard calculation.
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*/
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if (lifetime == 0U) {
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timeout->wrap_counter = 0;
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timeout->timer_timeout = 0;
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return;
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}
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expire_timeout = (uint64_t)MSEC_PER_SEC * (uint64_t)lifetime;
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timeout->wrap_counter = expire_timeout /
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(uint64_t)NET_TIMEOUT_MAX_VALUE;
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timeout->timer_timeout = expire_timeout -
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(uint64_t)NET_TIMEOUT_MAX_VALUE *
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(uint64_t)timeout->wrap_counter;
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/* The implementation requires that the fractional timeout be zero
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* only when the timeout has completed, so if the residual is zero
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* copy over one timeout from the wrap.
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*/
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if (timeout->timer_timeout == 0U) {
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timeout->timer_timeout = NET_TIMEOUT_MAX_VALUE;
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timeout->wrap_counter -= 1;
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}
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}
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int64_t net_timeout_deadline(const struct net_timeout *timeout,
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int64_t now)
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{
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uint64_t start;
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uint64_t deadline;
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/* Reconstruct the full-precision start time assuming that the full
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* precision start time is less than 2^32 ticks in the past.
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*/
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start = (uint64_t)now;
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start -= (uint32_t)now - timeout->timer_start;
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/* Offset the start time by the full precision remaining delay. */
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deadline = start + timeout->timer_timeout;
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deadline += (uint64_t)NET_TIMEOUT_MAX_VALUE
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* (uint64_t)timeout->wrap_counter;
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return (int64_t)deadline;
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}
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uint32_t net_timeout_remaining(const struct net_timeout *timeout,
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uint32_t now)
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{
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int64_t ret = timeout->timer_timeout;
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ret += timeout->wrap_counter * (uint64_t)NET_TIMEOUT_MAX_VALUE;
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ret -= (int64_t)(int32_t)(now - timeout->timer_start);
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if (ret <= 0) {
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return 0;
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}
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return (uint32_t)((uint64_t)ret / MSEC_PER_SEC);
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}
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uint32_t net_timeout_evaluate(struct net_timeout *timeout,
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uint32_t now)
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{
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uint32_t elapsed;
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uint32_t last_delay;
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int32_t remains;
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bool wraps;
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/* Time since last evaluation or set. */
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elapsed = now - timeout->timer_start;
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/* The delay used the last time this was evaluated. */
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wraps = (timeout->wrap_counter > 0U);
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last_delay = wraps
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? NET_TIMEOUT_MAX_VALUE
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: timeout->timer_timeout;
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/* Time remaining until completion of the last delay. */
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remains = (int32_t)(last_delay - elapsed);
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/* If the deadline for the next event hasn't been reached yet just
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* return the remaining time.
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*/
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if (remains > 0) {
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return (uint32_t)remains;
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}
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/* Deadline has been reached. If we're not wrapping we've completed
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* the last portion of the full timeout, so return zero to indicate
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* the timeout has completed.
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*/
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if (!wraps) {
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return 0U;
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}
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/* There's more to do. We need to update timer_start to correspond to
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* now, then reduce the remaining time by the elapsed time. We know
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* that's at least NET_TIMEOUT_MAX_VALUE, and can apply the
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* reduction by decrementing the wrap count.
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*/
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timeout->timer_start = now;
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elapsed -= NET_TIMEOUT_MAX_VALUE;
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timeout->wrap_counter -= 1;
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/* The residual elapsed must reduce timer_timeout, which is capped at
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* NET_TIMEOUT_MAX_VALUE. But if subtracting would reduce the
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* counter to zero or go negative we need to reduce the the wrap
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* counter once more and add the residual to the counter, so the
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* counter remains positive.
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*/
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if (timeout->timer_timeout > elapsed) {
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timeout->timer_timeout -= elapsed;
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} else {
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timeout->timer_timeout += NET_TIMEOUT_MAX_VALUE - elapsed;
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timeout->wrap_counter -= 1U;
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}
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return (timeout->wrap_counter == 0U)
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? timeout->timer_timeout
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: NET_TIMEOUT_MAX_VALUE;
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}
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