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130 lines
4.3 KiB
C++
130 lines
4.3 KiB
C++
//
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// 68000Mk2Storage.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 16/05/2022.
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// Copyright © 2022 Thomas Harte. All rights reserved.
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//
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#ifndef _8000Mk2Storage_h
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#define _8000Mk2Storage_h
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#include "../../../InstructionSets/M68k/Decoder.hpp"
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#include "../../../InstructionSets/M68k/Perform.hpp"
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#include "../../../InstructionSets/M68k/Status.hpp"
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namespace CPU {
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namespace MC68000Mk2 {
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struct ProcessorBase: public InstructionSet::M68k::NullFlowController {
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/// States for the state machine which are named by
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/// me for their purpose rather than automatically by file position.
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/// These are negative to avoid ambiguity with the other group.
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enum State: int {
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Reset = -1,
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Decode = -2,
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WaitForDTACK = -3,
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FetchOperand = -4,
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StoreOperand = -5,
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// Various different effective address calculations.
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CalculateAnDn = -5,
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// Various forms of perform; each of these will
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// perform the current instruction, then do the
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// indicated bus cycle.
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Perform_np = -6,
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Perform_np_n = -7,
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};
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int state_ = State::Reset;
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/// Counts time left on the clock before the current batch of processing
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/// is complete; may be less than zero.
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HalfCycles time_remaining_;
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/// Current supervisor state, for direct provision to the bus handler.
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int is_supervisor_ = 1;
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// A decoder for instructions, plus all collected information about the
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// current instruction.
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InstructionSet::M68k::Predecoder<InstructionSet::M68k::Model::M68000> decoder_;
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InstructionSet::M68k::Preinstruction instruction_;
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uint16_t opcode_;
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uint8_t operand_flags_;
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uint32_t instruction_address_;
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// Register state.
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InstructionSet::M68k::Status status_;
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SlicedInt32 program_counter_;
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SlicedInt32 registers_[16]; // D0–D7 followed by A0–A7.
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SlicedInt32 stack_pointers_[2];
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/// Current state of the DTACK input.
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bool dtack_ = false;
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/// Current state of the VPA input.
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bool vpa_ = false;
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/// Current state of the BERR input.
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bool berr_ = false;
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/// Contains the prefetch queue; the most-recently fetched thing is the
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/// low portion of this word, and the thing fetched before that has
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/// proceeded to the high portion.
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SlicedInt32 prefetch_;
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// Temporary storage for the current instruction's operands
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// and the corresponding effective addresses.
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CPU::SlicedInt32 operand_[2];
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uint32_t effective_address_[2];
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/// If currently in the wait-for-DTACK state, this indicates where to go
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/// upon receipt of DTACK or VPA. BERR will automatically segue
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/// into the proper exception.
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int post_dtack_state_ = 0;
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/// The perform state for this operation.
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int perform_state_ = 0;
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/// When fetching or storing operands, this is the next one to fetch
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/// or store.
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int next_operand_ = 0;
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// Flow controller... all TODO.
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using Preinstruction = InstructionSet::M68k::Preinstruction;
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template <typename IntT> void did_mulu(IntT) {}
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template <typename IntT> void did_muls(IntT) {}
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void did_chk([[maybe_unused]] bool was_under, [[maybe_unused]] bool was_over) {}
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void did_shift([[maybe_unused]] int bit_count) {}
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template <bool did_overflow> void did_divu([[maybe_unused]] uint32_t dividend, [[maybe_unused]] uint32_t divisor) {}
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template <bool did_overflow> void did_divs([[maybe_unused]] int32_t dividend, [[maybe_unused]] int32_t divisor) {}
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void did_bit_op([[maybe_unused]] int bit_position) {}
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inline void did_update_status();
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template <typename IntT> void complete_bcc(bool matched_condition, IntT offset) {}
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void complete_dbcc(bool matched_condition, bool overflowed, int16_t offset) {}
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void bsr(uint32_t offset) {}
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void jsr(uint32_t address) {}
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void jmp(uint32_t address) {}
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void rtr() {}
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void rte() {}
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void rts() {}
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void stop() {}
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void reset() {}
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void link(Preinstruction instruction, uint32_t offset) {}
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void unlink(uint32_t &address) {}
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void pea(uint32_t address) {}
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void move_to_usp(uint32_t address) {}
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void move_from_usp(uint32_t &address) {}
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void tas(Preinstruction instruction, uint32_t address) {}
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template <typename IntT> void movep(Preinstruction instruction, uint32_t source, uint32_t dest) {}
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template <typename IntT> void movem_toM(Preinstruction instruction, uint32_t mask, uint32_t address) {}
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template <typename IntT> void movem_toR(Preinstruction instruction, uint32_t mask, uint32_t address) {}
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template <bool use_current_instruction_pc = true> void raise_exception([[maybe_unused]] int vector) {}
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};
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}
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}
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#endif /* _8000Mk2Storage_h */
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