z80

Description:

z80

Zilog Z80 microprocessor emulator #
Maintained by: Simon Lightfoot @slightfoot
This is an emulator for the Z80 processor, ported to Dart from JS and is a simple,
straightforward instruction interpreter. There is no fancy dynamic recompilation
or cycle-accurate emulation. It is developed to serve as a component of a larger
system which incorporates a Z80 as its CPU.
The code assumes that the reader is familiar with the Z80 architecture.
If you're not, here are some references:

Z80 instruction set tables
The official manual
The Undocumented Z80, Documented

Usage #
A simple usage from example/main.dart:
import 'dart:typed_data';

import 'package:z80/z80.dart';

void main() {
var system = System();
system.memWrite(0, 1);
// 0000| $A8 XOR b
// 0001| $0E LD c, [address]
// 0002| $07 [address]
// 0003| $0A LD a, (bc)
// 0004| $3C inc a
// 0005| $02 LD (bc), a
// 0006| $76 HALT
// 0007| $AA
system.load(0, [0xA8, 0x0E, 0x07, 0x0A, 0x3C, 0x02, 0x76, 0xAA]);
print('before ram[7] = ${system.memRead(7).toRadixString(16)}');
system.run();
print('after ram[7] = ${system.memRead(7).toRadixString(16)}');
//
// Expected output:
//
// before ram[7] = aa
// after ram[7] = ab
//
}

class System implements Z80Core {
System() {
_cpu = Z80CPU(this);
_ram = Uint8ClampedList(32 * 1024); // 32K
}

late final Z80CPU _cpu;
late final Uint8ClampedList _ram;

void load(int address, List<int> data) {
_ram.setRange(address, address + data.length, data);
}

int run([int cycles = 0]) {
if (cycles == 0) {
while (!_cpu.isHalted()) {
cycles -= _cpu.runInstruction();
}
} else {
while (!_cpu.isHalted() && cycles > 0) {
cycles -= _cpu.runInstruction();
}
}
return cycles;
}

@override
int memRead(int address) => _ram[address];

@override
void memWrite(int address, int value) => _ram[address] = value;

@override
int ioRead(int port) => 0;

@override
void ioWrite(int port, int value) {}
}
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Features and bugs #
Please file feature requests and bugs at the issue tracker.
License #
This code is copyright Molly Howell, Simon Lightfoot and contributors and is made
available under the MIT license. The text of the MIT license can be found in the
LICENSE file in this repository.
Ported from: https://github.com/DrGoldfire/Z80.js