6502/EightBit
1
0
Fork 0
mirror of https://github.com/MoleskiCoder/EightBit.git synced 2025-04-17 22:38:11 +00:00
Code Issues Projects Releases Wiki Activity

MC6809 tidy a few items and show a "functional" (rather than macro based) rmw routine.

Browse Source
This commit is contained in:
Adrian Conlon 2020-04-06 23:08:11 +01:00
parent ff02159886
commit 7296ff7cce
2 changed files with 40 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
MC6809/inc/mc6809.h
View File

@ -4,6 +4,7 @@
// http://www.cpu-world.com/Arch/6809.html
#include <cstdint>
#include <functional>
#include <Bus.h>
#include <BigEndianProcessor.h>
@ -112,6 +113,7 @@ namespace EightBit {
virtual uint8_t busRead() final;
virtual void call(register16_t destination) final;
virtual void ret() final;
private:
const uint8_t RESETvector = 0xfe; // RESET vector
@ -125,7 +127,33 @@ namespace EightBit {
void eat(int cycles = 1) {
for (int cycle = 0; cycle < cycles; ++cycle)
memoryRead(0xffff);
memoryRead(Mask16);
}
// Read/Modify/Write
// Macro version: easy to use
// RMW(AM_direct_byte, asl)
#define RMW(ACCESSOR, OPERATION) \
{ \
const auto data = ACCESSOR(); \
const auto address = BUS().ADDRESS(); \
const auto result = OPERATION(data); \
eat(); \
memoryWrite(address, result); \
}
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);
}
// Stack manipulation
@ -363,7 +391,6 @@ namespace EightBit {
uint8_t rol(uint8_t operand);
uint8_t ror(uint8_t operand);
void rti();
void rts();
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);

32
MC6809/src/mc6809.cpp
View File

@ -4,16 +4,6 @@
#include <algorithm>
#include <cassert>
// Read/Modify/Write
#define RMW(ACCESSOR, OPERATION) \
{ \
const auto data = ACCESSOR(); \
const auto address = BUS().ADDRESS(); \
const auto result = OPERATION(data); \
eat(); \
memoryWrite(address, result); \
}
EightBit::mc6809::mc6809(Bus& bus)
: BigEndianProcessor(bus) {
RaisedPOWER.connect([this](EventArgs) {
@ -61,17 +51,17 @@ void EightBit::mc6809::handleHALT() {
void EightBit::mc6809::handleRESET() {
BigEndianProcessor::handleRESET();
memoryRead(0xfffe);
memoryRead({ 0xff, RESETvector });
raiseNMI();
lowerBA();
raiseBS();
DP() = 0;
CC() = setBit(CC(), IF); // Disable IRQ
CC() = setBit(CC(), FF); // Disable FIRQ
memoryRead(0xfffe);
memoryRead(0xfffe);
memoryRead(0xfffe);
jump(getWordPaged(0xff, RESETvector));
memoryRead();
memoryRead();
memoryRead();
jump(getWord());
eat();
}
@ -142,6 +132,11 @@ void EightBit::mc6809::call(register16_t destination) {
jump(destination);
}
void EightBit::mc6809::ret() {
BigEndianProcessor::ret();
eat();
}
//
int EightBit::mc6809::execute() {
@ -421,7 +416,7 @@ void EightBit::mc6809::executeUnprefixed() {
case 0x3B: memoryRead(); rti(); break; // RTI (inherent)
// RTS
case 0x39: memoryRead(); rts(); break; // RTS (inherent)
case 0x39: memoryRead(); ret(); break; // RTS (inherent)
// SBC
@ -1088,11 +1083,6 @@ void EightBit::mc6809::rti() {
eat();
}
void EightBit::mc6809::rts() {
ret();
eat();
}
void EightBit::mc6809::swi() {
eat();
saveEntireRegisterState();