EightBit/MC6809/inc/mc6809.h
2024-03-14 14:54:52 +00:00

403 lines
14 KiB
C++

#pragma once
// Uses some information from:
// http://www.cpu-world.com/Arch/6809.html
#include <cstdint>
#include <functional>
#include <Bus.h>
#include <BigEndianProcessor.h>
#include <Signal.h>
#include <Register.h>
namespace EightBit {
class mc6809 : public BigEndianProcessor {
public:
DECLARE_PIN_INPUT(NMI)
DECLARE_PIN_INPUT(FIRQ)
DECLARE_PIN_INPUT(HALT)
DECLARE_PIN_OUTPUT(BA)
DECLARE_PIN_OUTPUT(BS)
DECLARE_PIN_OUTPUT(RW)
public:
enum StatusBits {
// Entire flag: set if the complete machine state was saved in the stack.
// If this bit is not set then only program counter and condition code
// registers were saved in the stack. This bit is used by interrupt
// handling routines only.
// The bit is cleared by fast interrupts, and set by all other interrupts.
EF = Bit7,
// Fast interrupt mask: set if the FIRQ interrupt is disabled.
FF = Bit6,
// Half carry: set if there was a carry from bit 3 to bit 4 of the result
// during the last add operation.
HF = Bit5,
// Interrupt mask: set if the IRQ interrupt is disabled.
IF = Bit4,
// Negative: set if the most significant bit of the result is set.
// This bit can be set not only by arithmetic and logical operations,
// but also by load / store operations.
NF = Bit3,
// Zero: set if the result is zero. Like the N bit, this bit can be
// set not only by arithmetic and logical operations, but also
// by load / store operations.
ZF = Bit2,
// Overflow: set if there was an overflow during last result calculation.
// Logical, load and store operations clear this bit.
VF = Bit1,
// Carry: set if there was a carry from the bit 7 during last add
// operation, or if there was a borrow from last subtract operation,
// or if bit 7 of the A register was set during last MUL operation.
CF = Bit0,
};
mc6809(Bus& bus);
Signal<mc6809> ExecutingInstruction;
Signal<mc6809> ExecutedInstruction;
void execute() noexcept final;
[[nodiscard]] int step() noexcept final;
[[nodiscard]] constexpr auto& D() noexcept { return m_d; }
[[nodiscard]] constexpr auto& A() noexcept { return D().high; }
[[nodiscard]] constexpr auto& B() noexcept { return D().low; }
[[nodiscard]] constexpr auto& X() noexcept { return m_x; }
[[nodiscard]] constexpr auto& Y() noexcept { return m_y; }
[[nodiscard]] constexpr auto& U() noexcept { return m_u; }
[[nodiscard]] constexpr auto& S() noexcept { return m_s; }
[[nodiscard]] constexpr auto& DP() noexcept { return m_dp; }
[[nodiscard]] constexpr auto& CC() noexcept { return m_cc; }
[[nodiscard]] constexpr const auto& CC() const noexcept { return m_cc; }
// Flag checking
[[nodiscard]] constexpr auto fastInterruptMasked() const noexcept { return CC() & FF; }
[[nodiscard]] constexpr auto interruptMasked() const noexcept { return CC() & IF; }
[[nodiscard]] constexpr auto negative() const noexcept { return CC() & NF; }
[[nodiscard]] constexpr auto zero() const noexcept { return CC() & ZF; }
[[nodiscard]] constexpr auto overflow() const noexcept { return CC() & VF; }
[[nodiscard]] constexpr auto carry() const noexcept { return CC() & CF; }
[[nodiscard]] constexpr auto halfCarry() const noexcept { return CC() & HF; }
// |---------------|-----------------------------------|
// | MPU State | |
// |_______________| MPU State Definition |
// | BA | BS | |
// |_______|_______|___________________________________|
// | 0 | 0 | Normal (running) |
// | 0 | 1 | Interrupt or RESET Acknowledge |
// | 1 | 0 | SYNC Acknowledge |
// | 1 | 1 | HALT Acknowledge |
// |-------|-------|-----------------------------------|
[[nodiscard]] auto halted() noexcept { return lowered(HALT()); }
void halt() noexcept { --PC(); lowerHALT(); }
void proceed() noexcept { ++PC(); raiseHALT(); }
protected:
// Default push/pop handlers
void push(uint8_t value) noexcept final;
[[nodiscard]] uint8_t pop() noexcept final;
// Interrupt (etc.) handlers
void handleRESET() noexcept final;
void handleINT() noexcept final;
// Bus reader/writers
void busWrite() noexcept final;
uint8_t busRead() noexcept final;
void call(register16_t destination) noexcept final;
void ret() noexcept final;
private:
const uint8_t RESETvector = 0xfe; // RESET vector
const uint8_t NMIvector = 0xfc; // NMI vector
const uint8_t SWIvector = 0xfa; // SWI vector
const uint8_t IRQvector = 0xf8; // IRQ vector
const uint8_t FIRQvector = 0xf6; // FIRQ vector
const uint8_t SWI2vector = 0xf4; // SWI2 vector
const uint8_t SWI3vector = 0xf2; // SWI3 vector
const uint8_t RESERVEDvector = 0xf0; // RESERVED vector
void eat(int cycles = 1) {
for (int cycle = 0; cycle < cycles; ++cycle)
memoryRead(Mask16);
}
// Read/Modify/Write
typedef std::function<uint8_t(void)> accessor_t;
typedef std::function<uint8_t(uint8_t)> operation_t;
// C++ 11 version: looks great, but verbose to use
// rmw([this]() { return AM_direct_byte(); }, [this](uint8_t data) { return asl(data); });
void rmw(accessor_t accessor, operation_t operation) {
const auto data = accessor();
const auto address = BUS().ADDRESS();
const auto result = operation(data);
eat();
memoryWrite(address, result);
}
// So define a helper macro
#define RMW(ACCESSOR, OPERATION) \
rmw([this]() { return ACCESSOR(); }, [this](uint8_t data) { return OPERATION(data); });
// Stack manipulation
void push(register16_t& stack, uint8_t value);
void pushS(const uint8_t value) { push(S(), value); }
void pushU(const uint8_t value) { push(U(), value); }
void pushWord(register16_t& stack, const register16_t value) {
push(stack, value.low);
push(stack, value.high);
}
void pushWordS(const register16_t value) { pushWord(S(), value); }
void pushWordU(const register16_t value) { pushWord(U(), value); }
[[nodiscard]] uint8_t pop(register16_t& stack);
[[nodiscard]] uint8_t popS() { return pop(S()); }
[[nodiscard]] uint8_t popU() { return pop(U()); }
[[nodiscard]] register16_t popWord(register16_t& stack) {
const auto high = pop(stack);
const auto low = pop(stack);
return register16_t(low, high);
}
[[nodiscard]] auto popWordS() { return popWord(S()); }
[[nodiscard]] auto popWordU() { return popWord(U()); }
// Interrupt (etc.) handlers
void handleHALT();
void handleNMI();
void handleFIRQ();
// Execution helpers
void executeUnprefixed();
void execute10();
void execute11();
// Register selection for "indexed"
[[nodiscard]] register16_t& RR(int which);
// Register selection for 8-bit transfer/exchange
[[nodiscard]] uint8_t& referenceTransfer8(int specifier) noexcept;
// Register selection for 16-bit transfer/exchange
[[nodiscard]] register16_t& referenceTransfer16(int specifier);
// Addressing modes
[[nodiscard]] register16_t Address_direct(); // DP + fetched offset
[[nodiscard]] register16_t Address_indexed(); // Indexed address, complicated!
[[nodiscard]] register16_t Address_extended(); // Fetched address
register16_t Address_relative_byte(); // PC + fetched byte offset
register16_t Address_relative_word(); // PC + fetched word offset
// Addressing mode readers
// Single byte readers
[[nodiscard]] uint8_t AM_immediate_byte();
[[nodiscard]] uint8_t AM_direct_byte();
[[nodiscard]] uint8_t AM_indexed_byte();
[[nodiscard]] uint8_t AM_extended_byte();
// Word readers
[[nodiscard]] register16_t AM_immediate_word();
[[nodiscard]] register16_t AM_direct_word();
[[nodiscard]] register16_t AM_indexed_word();
[[nodiscard]] register16_t AM_extended_word();
// Flag adjustment
template<class T> constexpr void adjustZero(const T datum) noexcept { CC() = clearBit(CC(), ZF, datum); }
constexpr void adjustZero(const register16_t datum) noexcept { CC() = clearBit(CC(), ZF, datum.word); }
constexpr void adjustNegative(const uint8_t datum) noexcept { CC() = setBit(CC(), NF, datum & Bit7); }
constexpr void adjustNegative(const register16_t datum) noexcept { adjustNegative(datum.high); }
constexpr void adjustNegative(const uint16_t datum) noexcept { adjustNegative(register16_t(datum)); }
template<class T> constexpr void adjustNZ(const T datum) noexcept {
adjustZero(datum);
adjustNegative(datum);
}
constexpr void adjustCarry(const uint16_t datum) noexcept { CC() = setBit(CC(), CF, datum & Bit8); } // 8-bit addition
constexpr void adjustCarry(const uint32_t datum) noexcept { CC() = setBit(CC(), CF, datum & Bit16); } // 16-bit addition
constexpr void adjustCarry(const register16_t datum) noexcept { adjustCarry(datum.word); }
constexpr void adjustBorrow(const uint16_t datum) noexcept { CC() = clearBit(CC(), CF, datum & Bit8); } // 8-bit subtraction
constexpr void adjustBorrow(const uint32_t datum) noexcept { CC() = clearBit(CC(), CF, datum & Bit16); } // 16-bit subtraction
constexpr void adjustBorrow(const register16_t datum) noexcept { adjustBorrow(datum.word); }
constexpr void adjustOverflow(const uint8_t before, const uint8_t data, const register16_t after) noexcept {
const uint8_t lowAfter = after.low;
const uint8_t highAfter = after.high;
CC() = setBit(CC(), VF, (before ^ data ^ lowAfter ^ (highAfter << 7)) & Bit7);
}
constexpr void adjustOverflow(const uint16_t before, const uint16_t data, const uint32_t after) noexcept {
const uint16_t lowAfter = after & Mask16;
const uint16_t highAfter = after >> 16;
CC() = setBit(CC(), VF, (before ^ data ^ lowAfter ^ (highAfter << 15)) & Bit15);
}
constexpr void adjustOverflow(const register16_t before, const register16_t data, const register16_t after) noexcept {
adjustOverflow(before.word, data.word, after.word);
}
constexpr void adjustHalfCarry(const uint8_t before, const uint8_t data, const uint8_t after) noexcept {
CC() = setBit(CC(), HF, (before ^ data ^ after) & Bit4);
}
constexpr void adjustAddition(const uint8_t before, const uint8_t data, const register16_t after) noexcept {
const auto result = after.low;
adjustNZ(result);
adjustCarry(after);
adjustOverflow(before, data, after);
adjustHalfCarry(before, data, result);
}
constexpr void adjustAddition(const uint16_t before, const uint16_t data, const uint32_t after) noexcept {
const register16_t result = after & Mask16;
adjustNZ(result);
adjustCarry(after);
adjustOverflow(before, data, after);
}
constexpr void adjustAddition(const register16_t before, const register16_t data, const uint32_t after) noexcept {
adjustAddition(before.word, data.word, after);
}
constexpr void adjustSubtraction(const uint8_t before, const uint8_t data, const register16_t after) noexcept {
const auto result = after.low;
adjustNZ(result);
adjustCarry(after);
adjustOverflow(before, data, after);
}
constexpr void adjustSubtraction(const uint16_t before, const uint16_t data, const uint32_t after) noexcept {
const register16_t result = after & Mask16;
adjustNZ(result);
adjustCarry(after);
adjustOverflow(before, data, after);
}
constexpr void adjustSubtraction(const register16_t before, const register16_t data, const uint32_t after) noexcept {
adjustSubtraction(before.word, data.word, after);
}
[[nodiscard]] constexpr auto LS() const noexcept { return carry() || zero(); } // (C OR Z)
[[nodiscard]] constexpr auto HI() const noexcept { return !LS(); } // !(C OR Z)
[[nodiscard]] constexpr auto LT() const noexcept { return (negative() >> 3) ^ (overflow() >> 1); } // (N XOR V)
[[nodiscard]] constexpr auto GE() const noexcept { return !LT(); } // !(N XOR V)
[[nodiscard]] constexpr auto LE() const noexcept { return zero() || LT(); } // (Z OR (N XOR V))
[[nodiscard]] constexpr auto GT() const noexcept { return !LE(); } // !(Z OR (N XOR V))
// Branching
auto branch(const register16_t destination, const bool condition) noexcept {
if (condition)
jump(destination);
return condition;
}
void branchShort(const bool condition) noexcept {
branch(Address_relative_byte(), condition);
}
void branchLong(const bool condition) {
if (branch(Address_relative_word(), condition))
eat();
}
// Miscellaneous
void saveEntireRegisterState();
void savePartialRegisterState();
void saveRegisterState();
void restoreRegisterState();
template <class T> constexpr T through(const T data) noexcept {
CC() = clearBit(CC(), VF);
adjustNZ(data);
return data;
}
// Instruction implementations
uint8_t adc(uint8_t operand, uint8_t data);
uint8_t add(uint8_t operand, uint8_t data, uint8_t carry = 0);
register16_t add(register16_t operand, register16_t data);
uint8_t andr(uint8_t operand, uint8_t data);
uint8_t asl(uint8_t operand);
uint8_t asr(uint8_t operand);
void bit(uint8_t operand, uint8_t data);
uint8_t clr(uint8_t data = 0); // In this form for Read/Modify/Write operations
void cmp(uint8_t operand, uint8_t data);
void cmp(register16_t operand, register16_t data);
uint8_t com(uint8_t operand);
void cwai(uint8_t data);
uint8_t da(uint8_t operand);
uint8_t dec(uint8_t operand);
[[nodiscard]] uint8_t eorr(uint8_t operand, uint8_t data) noexcept;
void exg(uint8_t data);
uint8_t inc(uint8_t operand);
void jsr(register16_t address);
uint8_t lsr(uint8_t operand);
register16_t mul(uint8_t first, uint8_t second);
uint8_t neg(uint8_t operand);
uint8_t orr(uint8_t operand, uint8_t data);
void psh(register16_t& stack, uint8_t data);
void pul(register16_t& stack, uint8_t data);
uint8_t rol(uint8_t operand);
uint8_t ror(uint8_t operand);
void rti();
uint8_t sbc(uint8_t operand, uint8_t data);
uint8_t sub(uint8_t operand, uint8_t data, uint8_t carry = 0);
register16_t sub(register16_t operand, register16_t data);
uint8_t sex(uint8_t from);
void swi();
void swi2();
void swi3();
void tfr(uint8_t data);
void tst(uint8_t data);
register16_t m_d;
register16_t m_x;
register16_t m_y;
register16_t m_u;
register16_t m_s;
uint8_t m_dp = 0;
uint8_t m_cc = 0;
bool m_prefix10 = false;
bool m_prefix11 = false;
};
}