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80 lines
1.8 KiB
C++
80 lines
1.8 KiB
C++
//
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// Sequencer.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 29/04/2022.
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// Copyright © 2022 Thomas Harte. All rights reserved.
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//
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#ifndef InstructionSets_68k_Sequencer_hpp
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#define InstructionSets_68k_Sequencer_hpp
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#include "Instruction.hpp"
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#include "Model.hpp"
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namespace InstructionSet {
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namespace M68k {
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enum class Step {
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/// No further steps remain.
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Done,
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/// Fetch the value of operand 1.
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FetchOp1,
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/// Fetch the value of operand 2.
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FetchOp2,
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/// Do the logical operation.
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Perform,
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/// A catch-all for bus activity that doesn't fit the pattern
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/// of fetch/stop operand 1/2, e.g. this opaquely covers almost
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/// the entirety of MOVEM.
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///
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/// TODO: list all operations that contain this step,
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/// and to cover what activity.
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SpecificBusActivity,
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/// Store the value of operand 1.
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StoreOp1,
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/// Store the value of operand 2.
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StoreOp2,
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/// Calculate effective address of operand 1.
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CalcEA1,
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/// Calculate effective address of operand 2.
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CalcEA2,
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Max = CalcEA2
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};
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/// Indicates the abstract steps necessary to perform an operation,
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/// at least as far as that's generic.
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template<Model model> class Sequence {
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public:
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Sequence(Operation);
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/// @returns The next @c Step to perform, or @c Done
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/// if no further steps remain. This step is removed from the
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/// list of remaining steps.
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Step pop_front() {
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static_assert(int(Step::Max) < 16);
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const auto step = Step(steps_ & 15);
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steps_ >>= 4;
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return step;
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}
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/// @returns @c true if no steps other than @c Done remain;
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/// @c false otherwise.
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bool empty() {
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return !steps_;
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}
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private:
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uint32_t steps_ = 0;
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uint32_t steps_for(Operation);
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};
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static_assert(sizeof(Sequence<Model::M68000>) == sizeof(uint32_t));
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}
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}
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#endif /* InstructionSets_68k_Sequencer_h */
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