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Takes a serious shot at back_map.

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Thomas Harte 2021-06-27 17:36:25 -04:00
parent be19fa9dde
commit 95c906f03d
1 changed files with 16 additions and 2 deletions
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18
ClockReceiver/JustInTime.hpp
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@ -207,8 +207,22 @@ template <class T, class LocalTimeScale = HalfCycles, int multiplier = 1, int di
/// Indicates the amount of time, in the local time scale, until the first local slot that falls wholly
/// after @c duration, if that delay were to occur in @c offset units of time from now.
[[nodiscard]] forceinline LocalTimeScale back_map(TargetTimeScale duration, TargetTimeScale offset) const {
// TODO.
return LocalTimeScale(0);
// A 1:1 mapping is easy.
if constexpr (multiplier == 1 && divider == 1) {
return duration;
}
// Work out when this query is placed, and the time to which it relates
const auto base = time_since_update_ + offset * divider;
const auto target = base + duration * divider;
// Figure out the number of whole input steps that is required to get
// past target, and subtract the number of whole input steps necessary
// to get to base.
const auto steps_to_base = base.as_integral() / divider;
const auto steps_to_target = (target.as_integral() + divider - 1) / divider;
return LocalTimeScale(steps_to_target - steps_to_base);
}
/// Updates this template's record of the next sequence point.