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CLK/ClockReceiver/Dispatcher.hpp

90 lines
2.4 KiB
C++

//
// Serialiser.hpp
// Clock Signal
//
// Created by Thomas Harte on 29/05/2023.
// Copyright © 2023 Thomas Harte. All rights reserved.
//
#ifndef Dispatcher_hpp
#define Dispatcherr_hpp
namespace Dispatcher {
/// The unity function; converts n directly to n.
struct UnitConverter {
constexpr int operator ()(int n) {
return n;
}
};
template <int max, typename SequencerT, typename ConverterT = UnitConverter>
struct Dispatcher {
/// Perform @c target.perform<n>() for the input range [start, end]; @c ConverterT()(n) will be applied to
/// each individual step before it becomes the relevant template argument.
void dispatch(SequencerT &target, int start, int end) {
// Minor optimisation: do a comparison with end once outside the loop and if it implies so
// then do no further comparisons within the loop. This is somewhat targetted at expected
// use cases.
if(end < max) {
dispatch<true>(target, start, end);
} else {
dispatch<false>(target, start, end);
}
}
private:
template <bool use_end> void dispatch(SequencerT &target, int start, int end) {
static_assert(max < 2048);
// Yes, macros, yuck. But I want an actual switch statement for the dispatch to start
// and to allow a simple [[fallthrough]] through all subsequent steps up until end.
// So I don't think I have much in the way of options here.
//
// Sensible choices by the optimiser are assumed.
#define index(n) \
if constexpr (n == max) return; \
if(use_end && end == n) return; \
[[fallthrough]]; \
case n: target.template perform<ConverterT()(n)>();
#define index2(n) index(n); index(n+1);
#define index4(n) index2(n); index2(n+2);
#define index8(n) index4(n); index4(n+4);
#define index16(n) index8(n); index8(n+8);
#define index32(n) index16(n); index16(n+16);
#define index64(n) index32(n); index32(n+32);
#define index128(n) index64(n); index64(n+64);
#define index256(n) index128(n); index128(n+128);
#define index512(n) index256(n); index256(n+256);
#define index1024(n) index512(n); index512(n+512);
#define index2048(n) index1024(n); index1024(n+1024);
switch(start) {
default: assert(false);
index2048(0);
}
#undef index
#undef index2
#undef index4
#undef index8
#undef index16
#undef index32
#undef index64
#undef index128
#undef index256
#undef index512
#undef index1024
#undef index2048
}
};
}
#endif /* Dispatcher_hpp */