mirror of
https://github.com/MoleskiCoder/EightBit.git
synced 2024-09-02 07:28:56 +00:00
126 lines
3.3 KiB
C++
126 lines
3.3 KiB
C++
#pragma once
|
|
|
|
// Uses some information from:
|
|
// http://www.cpu-world.com/Arch/6809.html
|
|
|
|
#include <cstdint>
|
|
|
|
#include <Bus.h>
|
|
#include <BigEndianProcessor.h>
|
|
|
|
namespace EightBit {
|
|
class mc6809 : public BigEndianProcessor {
|
|
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;
|
|
|
|
virtual int execute(uint8_t opcode) final;
|
|
virtual int step() final;
|
|
virtual void powerOn() final;
|
|
|
|
register16_t& D() { return m_d; }
|
|
uint8_t& A() { return D().high; }
|
|
uint8_t& B() { return D().low; }
|
|
|
|
register16_t& X() { return m_x; }
|
|
register16_t& Y() { return m_y; }
|
|
register16_t& U() { return m_u; }
|
|
register16_t& S() { return m_s; }
|
|
|
|
uint8_t& DP() { return m_dp; }
|
|
uint8_t& CC() { return m_cc; }
|
|
|
|
PinLevel& IRQ() { return INT(); }
|
|
PinLevel& FIRQ() { return m_firq; }
|
|
|
|
protected:
|
|
virtual void reset() final;
|
|
|
|
private:
|
|
const uint8_t RESETvector = 0xfe;
|
|
const uint8_t NMIvector = 0xfc;
|
|
const uint8_t SWIvector = 0xfa;
|
|
const uint8_t IRQvector = 0xf8;
|
|
const uint8_t FIRQvector = 0xf6;
|
|
const uint8_t SWI2vector = 0xf4;
|
|
const uint8_t SWI3vector = 0xf2;
|
|
const uint8_t RESERVEDvector = 0xf0;
|
|
|
|
// Register selection for "indexed"
|
|
register16_t& RR(int which);
|
|
|
|
// Addressing modes
|
|
void Address_direct();
|
|
void Address_indexed();
|
|
void Address_extended();
|
|
|
|
// Addressing mode readers
|
|
uint8_t AM_immediate_byte();
|
|
uint8_t AM_direct_byte();
|
|
uint8_t AM_indexed_byte();
|
|
uint8_t AM_extended_byte();
|
|
|
|
register16_t AM_immediate_word();
|
|
register16_t AM_direct_word();
|
|
register16_t AM_indexed_word();
|
|
register16_t AM_extended_word();
|
|
|
|
void abx();
|
|
uint8_t adc(uint8_t operand, uint8_t data);
|
|
uint8_t add(uint8_t operand, uint8_t data, int carry = 0);
|
|
register16_t add(register16_t operand, register16_t data);
|
|
uint8_t neg(uint8_t operand);
|
|
|
|
register16_t m_d;
|
|
register16_t m_x;
|
|
register16_t m_y;
|
|
register16_t m_u;
|
|
register16_t m_s;
|
|
|
|
uint8_t m_dp;
|
|
uint8_t m_cc;
|
|
|
|
PinLevel m_firq;
|
|
};
|
|
} |