EightBit/inc/Processor.h

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C
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#pragma once
#include <cstdint>
#include "Bus.h"
#include "Register.h"
#include "EightBitCompilerDefinitions.h"
namespace EightBit {
class Processor {
public:
enum Bits {
Bit0 = 1,
Bit1 = Bit0 << 1,
Bit2 = Bit1 << 1,
Bit3 = Bit2 << 1,
Bit4 = Bit3 << 1,
Bit5 = Bit4 << 1,
Bit6 = Bit5 << 1,
Bit7 = Bit6 << 1,
Bit8 = Bit7 << 1,
Bit9 = Bit8 << 1,
Bit10 = Bit9 << 1,
Bit11 = Bit10 << 1,
Bit12 = Bit11 << 1,
Bit13 = Bit12 << 1,
Bit14 = Bit13 << 1,
Bit15 = Bit14 << 1,
Bit16 = Bit15 << 1
};
enum Masks {
Mask1 = Bit1 - 1,
Mask2 = Bit2 - 1,
Mask3 = Bit3 - 1,
Mask4 = Bit4 - 1,
Mask5 = Bit5 - 1,
Mask6 = Bit6 - 1,
Mask7 = Bit7 - 1,
Mask8 = Bit8 - 1,
Mask9 = Bit9 - 1,
Mask10 = Bit10 - 1,
Mask11 = Bit11 - 1,
Mask12 = Bit12 - 1,
Mask13 = Bit13 - 1,
Mask14 = Bit14 - 1,
Mask15 = Bit15 - 1,
Mask16 = Bit16 - 1
};
enum PinLevel {
Low, High
};
static bool raised(const PinLevel line) { return line == High; }
static void raise(PinLevel& line) { line = High; }
static bool lowered(const PinLevel line) { return line == Low; }
static void lower(PinLevel& line) { line = Low; }
static int highNibble(const int value) { return value >> 4; }
static int lowNibble(const int value) { return value & Mask4; }
static int higherNibble(const int value) { return value & 0xf0; }
static int lowerNibble(const int value) { return lowNibble(value); }
static int promoteNibble(const int value) { return value << 4; }
static int demoteNibble(const int value) { return highNibble(value); }
// b: number of bits representing the number in x
// x: sign extend this b-bit number to r
static int8_t signExtend(int b, uint8_t x);
Bus& BUS() { return m_bus; }
register16_t& PC() { return m_pc; }
PinLevel& RESET() { return m_resetLine; }
PinLevel& HALT() { return m_haltLine; }
PinLevel& INT() { return m_intLine; }
PinLevel& IRQ() { return INT(); } // Synonym
PinLevel& POWER() { return m_powerLine; }
bool powered() { return raised(POWER()); }
virtual void powerOn();
void powerOff() { lower(POWER()); }
void reset() { lower(RESET()); }
int run(int limit);
virtual int step() = 0;
virtual int execute(uint8_t opcode) = 0;
int cycles() const { return m_cycles; }
virtual register16_t peekWord(register16_t address) = 0;
protected:
static void clearFlag(uint8_t& f, const int flag) { f &= ~flag; }
static void setFlag(uint8_t& f, const int flag) { f |= flag; }
static void setFlag(uint8_t& f, const int flag, const int condition) { setFlag(f, flag, !!condition); }
static void setFlag(uint8_t& f, const int flag, const uint32_t condition) { setFlag(f, flag, !!condition); }
static void setFlag(uint8_t& f, const int flag, const bool condition) { condition ? setFlag(f, flag) : clearFlag(f, flag); }
static void clearFlag(uint8_t& f, const int flag, const int condition) { clearFlag(f, flag, !!condition); }
static void clearFlag(uint8_t& f, const int flag, const uint32_t condition) { clearFlag(f, flag, !!condition); }
static void clearFlag(uint8_t& f, const int flag, const bool condition) { setFlag(f, flag, !condition); }
Processor(Bus& memory);
virtual ~Processor() = default;
bool halted() { return lowered(HALT()); }
void halt() { --PC(); lower(HALT()); }
void proceed() { ++PC(); raise(HALT()); }
virtual void handleRESET();
virtual void handleINT();
virtual void handleIRQ();
uint8_t getBytePaged(uint8_t page, uint8_t offset) {
return BUS().read(register16_t(offset, page));
}
void setBytePaged(uint8_t page, uint8_t offset, uint8_t value) {
BUS().write(register16_t(offset, page), value);
}
uint8_t fetchByte() {
return BUS().read(PC()++);
}
virtual register16_t getWord() = 0;
virtual void setWord(register16_t value) = 0;
virtual register16_t getWordPaged(uint8_t page, uint8_t offset) = 0;
virtual void setWordPaged(uint8_t page, uint8_t offset, register16_t value) = 0;
virtual register16_t fetchWord() = 0;
virtual void push(uint8_t value) = 0;
virtual uint8_t pop() = 0;
virtual void pushWord(const register16_t value) = 0;
virtual register16_t popWord() = 0;
register16_t getWord(register16_t address) {
BUS().ADDRESS() = address;
return getWord();
}
void setWord(register16_t address, register16_t value) {
BUS().ADDRESS() = address;
return setWord(value);
}
void jump(const register16_t destination) {
PC() = destination;
}
void call(const register16_t destination) {
pushWord(PC());
jump(destination);
}
virtual void ret() {
jump(popWord());
}
void resetCycles() { m_cycles = 0; }
void addCycles(const int extra) { m_cycles += extra; }
void addCycle() { ++m_cycles; }
private:
Bus& m_bus;
int m_cycles = 0;
register16_t m_pc;
PinLevel m_intLine = Low;
PinLevel m_haltLine = Low;
PinLevel m_resetLine = Low;
PinLevel m_powerLine = Low;
};
}