bus.cc

来自「AVR 单片机程序设计用到的模拟器」· CC 代码 · 共 57 行

/* $Id: Bus.cc,v 1.4 2000/09/24 12:57:54 pure Exp $ */

#include <iostream.h>
#include "Bus.h"

Bus::Bus() {
	root = 0;
}

void Bus::attach(Device* device)
{
	device->next = (Device*) 0;
	if (!root) {
		root = device;
		return;
	}
	Device* p = root;
	while (p->next) p = p->next;
	p->next = device;
}

byte Bus::readb(unsigned addr)
{
	for (Device* p = root; p; p = p->next) {
		if (p->cs(addr)) {
			return p->readb(addr);
		}
	}
	cerr << __FILE__ << ": reading from illegal address " << hex << addr << endl;
}

void Bus::writeb(unsigned addr, byte data)
{
	for (Device* p = root; p; p = p->next) {
		if (p->cs(addr)) {
			p->writeb(addr, data);
			return;
		}
	}
	cerr << __FILE__ << ": writing to illegal address " << hex << addr << endl;
}

unsigned Bus::irq()
{
	unsigned highest_prio = 0xffffffff;
	for (Device* p = root; p; p = p->next) {
		unsigned n = p->irq();
		if (n < highest_prio) {
			highest_prio = n;
		}
	}
	return highest_prio;
}