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https://github.com/MoleskiCoder/EightBit.git
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90 lines
2.6 KiB
C++
90 lines
2.6 KiB
C++
#pragma once
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#include <cstdint>
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#include "ClockedChip.h"
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#include "Bus.h"
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#include "Register.h"
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#include "EightBitCompilerDefinitions.h"
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namespace EightBit {
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class Processor : public ClockedChip {
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public:
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// http://graphics.stanford.edu/~seander/bithacks.html#FixedSignExtend
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// b: number of bits representing the number in x
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// x: sign extend this b-bit number to r
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[[nodiscard]] static constexpr int8_t signExtend(int b, uint8_t x) noexcept {
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const uint8_t m = bit(b - 1); // mask can be pre-computed if b is fixed
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x = x & (bit(b) - 1); // (Skip this if bits in x above position b are already zero.)
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const auto result = (x ^ m) - m;
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return result;
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}
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virtual ~Processor() noexcept {}
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[[nodiscard]] constexpr auto& PC() noexcept { return m_pc; }
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int run(int limit);
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virtual int step() = 0;
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virtual int execute() = 0;
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int execute(uint8_t value);
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[[nodiscard]] virtual register16_t peekWord(register16_t address) noexcept = 0;
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virtual void pokeWord(register16_t address, register16_t value) noexcept = 0;
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DECLARE_PIN_INPUT(RESET)
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DECLARE_PIN_INPUT(INT)
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protected:
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Processor(Bus& memory) noexcept;
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[[nodiscard]] constexpr auto& opcode() noexcept { return m_opcode; }
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[[nodiscard]] constexpr auto& BUS() noexcept { return m_bus; }
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virtual void handleRESET();
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virtual void handleINT();
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void memoryWrite(register16_t address, uint8_t data);
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void memoryWrite(register16_t address);
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void memoryWrite(uint8_t data);
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virtual void memoryWrite();
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virtual void busWrite();
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uint8_t memoryRead(register16_t address);
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virtual uint8_t memoryRead();
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virtual uint8_t busRead();
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uint8_t getBytePaged(uint8_t page, uint8_t offset);
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void setBytePaged(uint8_t page, uint8_t offset, uint8_t value);
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uint8_t fetchByte();
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[[nodiscard]] virtual register16_t getWord() = 0;
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virtual void setWord(register16_t value) = 0;
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[[nodiscard]] virtual register16_t getWordPaged(uint8_t page, uint8_t offset) = 0;
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virtual void setWordPaged(uint8_t page, uint8_t offset, register16_t value) = 0;
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[[nodiscard]] virtual register16_t fetchWord() = 0;
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virtual void push(uint8_t value) = 0;
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[[nodiscard]] virtual uint8_t pop() = 0;
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virtual void pushWord(register16_t value) = 0;
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[[nodiscard]] virtual register16_t popWord() = 0;
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[[nodiscard]] register16_t getWord(register16_t address);
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void setWord(register16_t address, register16_t value);
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void jump(const register16_t destination) noexcept;
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virtual void call(register16_t destination);
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virtual void ret();
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private:
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Bus& m_bus;
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uint8_t m_opcode = Mask8;
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register16_t m_pc;
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};
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}
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