1
0
mirror of https://github.com/TomHarte/CLK.git synced 2025-08-08 14:25:05 +00:00
Files
CLK/ClockReceiver/Dispatcher.hpp

133 lines
3.7 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 {
/// Provides glue for a run of calls like:
///
/// SequencerT.perform<0>(...)
/// SequencerT.perform<1>(...)
/// SequencerT.perform<2>(...)
/// ...etc...
///
/// Allowing the caller to execute any subrange of the calls.
template <typename SequencerT>
struct Dispatcher {
/// Perform @c target.perform<n>() for the input range `start <= n < end`.
template <typename... Args>
void dispatch(SequencerT &target, int start, int end, Args&&... args) {
// 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 < SequencerT::max) {
dispatch<true>(target, start, end, args...);
} else {
dispatch<false>(target, start, end, args...);
}
}
private:
template <bool use_end, typename... Args> void dispatch(SequencerT &target, int start, int end, Args&&... args) {
static_assert(SequencerT::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) \
case n: \
if constexpr (n <= SequencerT::max) { \
if constexpr (n == SequencerT::max) return; \
if constexpr (n < SequencerT::max) { \
if(use_end && end == n) return; \
} \
target.template perform<n>(start, end, args...); \
} \
[[fallthrough]];
#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
}
};
/// An optional target for a Dispatcher which uses a classifier to divide the input region into typed ranges, issuing calls to the target
/// only to begin and end each subrange, and for the number of cycles spent within.
template <typename ClassifierT, TargetT>
struct RangeDispatcher {
static constexpr int max = ClassifierT::max;
template <int n, typename... Args>
void perform(int begin, int end, Arg&&... args) {
constexpr auto region = ClassifierT::region(n);
const auto clipped_start = std::max(start, find_begin(n));
const auto clipped_end = std::min(end, find_end(n));
if constexpr (n == find_begin(n)) {
target.begin<region>(clipped_start);
}
target.advance<region>(clipped_end - clipped_start);
if constexpr (n + 1 == find_end(n)) {
target.end<region>(clipped_end);
}
}
private:
constexpr int find_begin(int n) {
const auto type = ClassifierT::region(n);
while(n && ClassifierT::region(n - 1) == type) --n;
return n;
}
constexpr int find_end(int n) {
const auto type = ClassifierT::region(n);
while(n < ClassifierT::max && ClassifierT::region(n) == type) ++n;
return n;
}
};
}
#endif /* Dispatcher_hpp */