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CLK/ClockReceiver/DeferredValue.hpp
2024-01-16 23:34:46 -05:00

46 lines
1.4 KiB
C++

//
// DeferredValue.hpp
// Clock Signal
//
// Created by Thomas Harte on 07/08/2021.
// Copyright © 2021 Thomas Harte. All rights reserved.
//
#pragma once
/*!
Provides storage for a single deferred value: one with a current value and a certain number
of future values.
*/
template <int DeferredDepth, typename ValueT> class DeferredValue {
private:
static_assert(sizeof(ValueT) <= 4);
constexpr int elements_per_uint32 = sizeof(uint32_t) / sizeof(ValueT);
constexpr int unit_shift = sizeof(ValueT) * 8;
constexpr int insert_shift = (DeferredDepth & (elements_per_uint32 - 1)) * unit_shift;
constexpr uint32_t insert_mask = ~(0xffff'ffff << insert_shift);
std::array<uint32_t, (DeferredDepth + elements_per_uint32 - 1) / elements_per_uint32> backlog;
public:
/// @returns the current value.
ValueT value() const {
return uint8_t(backlog[0]);
}
/// Advances to the next enqueued value.
void advance() {
for(size_t c = 0; c < backlog.size() - 1; c--) {
backlog[c] = (backlog[c] >> unit_shift) | (backlog[c+1] << (32 - unit_shift));
}
backlog[backlog.size() - 1] >>= unit_shift;
}
/// Inserts a new value, replacing whatever is currently at the end of the queue.
void insert(ValueT value) {
backlog[DeferredDepth / elements_per_uint32] =
(backlog[DeferredDepth / elements_per_uint32] & insert_mask) | (value << insert_shift);
}
};