EightBit/inc/Processor.h
Adrian Conlon 03b536838b Some constexpr improvements in low level classes.
Signed-off-by: Adrian Conlon <adrian.conlon@gmail.com>
2021-10-24 11:12:23 +01:00

90 lines
2.6 KiB
C++

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