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88 lines
2.8 KiB
C++
88 lines
2.8 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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/* 0x00 – 0x0f */
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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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/* 0x10 – 0x1f */
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Map(0x10, BPL, Relative); Map(0x11, ORA, IndirectY);
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Map(0x12, CLT, Implied); Map(0x13, BBC, Bit0AccumulatorRelative);
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Map(0x15, ORA, ZeroPageX);
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Map(0x16, ASL, ZeroPageX); Map(0x17, BBC, Bit0ZeroPageRelative);
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Map(0x18, CLC, Implied); Map(0x19, ORA, AbsoluteY);
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Map(0x1a, DEC, Accumulator); Map(0x1b, CLB, Bit0Accumulator);
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Map(0x1d, ORA, AbsoluteX);
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Map(0x1e, ASL, AbsoluteX); Map(0x1f, CLB, Bit0ZeroPage);
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/* 0x20 – 0x2f */
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Map(0x20, JSR, Absolute); Map(0x21, AND, XIndirect);
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Map(0x22, JSR, SpecialPage); Map(0x23, BBS, Bit1AccumulatorRelative);
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Map(0x24, BIT, ZeroPage); Map(0x25, AND, ZeroPage);
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Map(0x26, ROL, ZeroPage); Map(0x27, BBS, Bit1ZeroPageRelative);
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Map(0x28, PLP, Implied); Map(0x29, AND, Immediate);
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Map(0x2a, ROL, Accumulator); Map(0x2b, SEB, Bit1Accumulator);
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Map(0x2c, BIT, Absolute); Map(0x2d, AND, Absolute);
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Map(0x2e, ROL, Absolute); Map(0x2f, SEB, Bit1ZeroPage);
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/* 0x30 – 0x3f */
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Map(0x30, BMI, Relative); Map(0x31, AND, IndirectY);
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Map(0x32, SET, Implied); Map(0x33, BBC, Bit1AccumulatorRelative);
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Map(0x35, AND, ZeroPageX);
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Map(0x36, ROL, ZeroPageX); Map(0x37, BBC, Bit1ZeroPageRelative);
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Map(0x38, SEC, Implied); Map(0x39, AND, AbsoluteY);
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Map(0x3a, INC, Accumulator); Map(0x3b, CLB, Bit1Accumulator);
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Map(0x3c, LDM, ImmediateZeroPage); Map(0x3d, AND, AbsoluteX);
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Map(0x3e, ROL, AbsoluteX); Map(0x3f, CLB, Bit1ZeroPage);
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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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