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84 lines
2.3 KiB
C++
84 lines
2.3 KiB
C++
//
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// 65816Implementation.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 23/09/2020.
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// Copyright © 2020 Thomas Harte. All rights reserved.
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//
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#ifndef WDC65816Implementation_h
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#define WDC65816Implementation_h
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class ProcessorStorage {
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public:
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ProcessorStorage();
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enum MicroOp: uint8_t {
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/// Fetches a byte from the program counter to the instruction buffer and increments the program counter.
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CycleFetchIncrementPC,
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/// Does a no-effect fetch from PC-1.
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CycleFetchPreviousPC,
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/// Fetches a byte from the data address to the data buffer and increments the data address.
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CycleFetchIncrementData,
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/// Stores a byte to the data address from the data buffer and increments the data address.
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CycleStoreIncrementData,
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/// Pushes a single byte from the data buffer to the stack.
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CyclePush,
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/// Skips the next micro-op if in emulation mode.
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OperationSkipIf8,
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/// Sets the data address by copying the final two bytes of the instruction buffer.
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OperationConstructAbsolute,
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/// Performs whatever operation goes with this program.
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OperationPerform,
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/// Complete this set of micr-ops.
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OperationMoveToNextProgram
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};
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enum Operation: uint8_t {
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// These perform the named operation using the value in the data buffer.
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ADC, AND, BIT, CMP, CPX, CPY, EOR, ORA, SBC,
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// These load the respective register from the data buffer.
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LDA, LDX, LDY,
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// These move the respective register (or value) to the data buffer.
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STA, STX, STY, STZ,
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/// Loads the PC with the operand from the instruction buffer.
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JMP,
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/// Loads the PC with the operand from the instruction buffer, placing
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/// the old PC into the data buffer.
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JSR,
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};
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struct Instruction {
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size_t program_offset;
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Operation operation;
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};
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Instruction instructions[256];
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private:
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std::vector<MicroOp> micro_ops_;
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size_t install_ops(std::initializer_list<MicroOp> ops) {
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// Just copy into place and return the index at which copying began.
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const size_t index = micro_ops_.size();
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micro_ops_.insert(micro_ops_.end(), ops.begin(), ops.end());
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return index;
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}
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void set_instruction(uint8_t opcode, size_t micro_ops, Operation operation) {
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instructions[opcode].program_offset = micro_ops;
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instructions[opcode].operation = operation;
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}
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};
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#endif /* WDC65816Implementation_h */
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