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48 lines
1.2 KiB
C++
48 lines
1.2 KiB
C++
//
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// Decoder.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 1/15/21.
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// Copyright © 2021 Thomas Harte. All rights reserved.
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//
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#include "Decoder.hpp"
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namespace InstructionSet {
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namespace M50740 {
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std::pair<int, InstructionSet::M50740::Instruction> Decoder::decode(const uint8_t *source, size_t length) {
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const uint8_t *const end = source + length;
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if(phase_ == Phase::Instruction && source != end) {
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const uint8_t instruction = *source;
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++source;
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++consumed_;
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switch(instruction) {
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default:
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return std::make_pair(1, Instruction());
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#define Map(opcode, operation, addressing_mode) case opcode: instr_ = Instruction(Operation::operation, AddressingMode::addressing_mode); break
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Map(0x00, BRK, Implied); Map(0x01, ORA, XIndirect);
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Map(0x02, JSR, ZeroPageIndirect); Map(0x03, BBS, Bit0AccumulatorRelative);
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Map(0x05, ORA, ZeroPage);
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Map(0x06, ASL, ZeroPage); Map(0x07, BBS, Bit0ZeroPageRelative);
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Map(0x08, PHP, Implied); Map(0x09, ORA, Immediate);
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Map(0x0a, ASL, Accumulator); Map(0x0b, SEB, Bit0Accumulator);
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Map(0x0d, ORA, Absolute);
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Map(0x0e, ASL, Absolute); Map(0x0f, SEB, Bit0ZeroPage);
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#undef Map
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}
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}
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return std::make_pair(0, Instruction());
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}
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}
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}
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