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78 lines
1.6 KiB
C++
78 lines
1.6 KiB
C++
//
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// Decoder.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 16/02/2024.
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// Copyright © 2024 Thomas Harte. All rights reserved.
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//
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#pragma once
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#include "Model.hpp"
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#include "Operation.hpp"
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#include <array>
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namespace InstructionSet::ARM {
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template <Model model>
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constexpr std::array<Operation, 256> operation_table() {
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std::array<Operation, 256> result{};
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for(int c = 0; c < 256; c++) {
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const uint32_t opcode = c << 20;
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if(((opcode >> 26) & 0b11) == 0b00) {
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result[c] = Operation((c >> 21) & 0xf);
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continue;
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}
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if(((opcode >> 25) & 0b111) == 0b101) {
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result[c] =
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((opcode >> 24) & 1) ? Operation::BranchWithLink : Operation::Branch;
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continue;
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}
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if(((opcode >> 22) & 0b111'111) == 0b000'000) {
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result[c] =
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((opcode >> 21) & 1) ? Operation::MultiplyWithAccumulate : Operation::Multiply;
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continue;
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}
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if(((opcode >> 26) & 0b11) == 0b01) {
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result[c] = Operation::SingleDataTransfer;
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continue;
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}
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if(((opcode >> 25) & 0b111) == 0b100) {
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result[c] = Operation::BlockDataTransfer;
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continue;
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}
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if(((opcode >> 24) & 0b1111) == 0b1111) {
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result[c] = Operation::SoftwareInterrupt;
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continue;
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}
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if(((opcode >> 24) & 0b1111) == 0b1110) {
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result[c] = Operation::CoprocessorDataOperationOrRegisterTransfer;
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continue;
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}
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if(((opcode >> 25) & 0b111) == 0b110) {
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result[c] = Operation::CoprocessorDataTransfer;
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continue;
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}
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result[c] = Operation::Undefined;
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}
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return result;
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}
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template <Model model>
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constexpr Operation operation(uint32_t opcode) {
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constexpr std::array<Operation, 256> operations = operation_table<model>();
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return operations[(opcode >> 20) & 0xff];
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}
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}
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