ccpu.cpp

#ifndef __PROGTEST__

#include <cstdio>
#include <cstdlib>
#include <cstdint>
#include "common.h"

using namespace std;
#endif /* __PROGTEST__ */

//-------------------------------------------------------------------------------------------------
CCPU::CCPU(uint8_t* memStart, uint32_t pageTableRoot)
{
	m_MemStart = memStart;
	m_PageTableRoot = pageTableRoot;
}

//-------------------------------------------------------------------------------------------------
bool CCPU::ReadInt(uint32_t address, uint32_t& value)
{
	if(address & 0x3) { return false; } // not aligned
	uint32_t* addr = virtual2Physical(address, false);
	if(!addr) { return false; }
	value = *addr;
	return true;
}

//-------------------------------------------------------------------------------------------------
bool CCPU::WriteInt(uint32_t address, uint32_t value)
{
	if(address & 0x3) { return false; } // not aligned
	uint32_t* addr = virtual2Physical(address, true);
	if(!addr) { return false; }
	*addr = value;
	return true;
}

//-------------------------------------------------------------------------------------------------
uint32_t* CCPU::virtual2Physical(uint32_t address, bool write)
{
	const uint32_t reqMask = BIT_PRESENT | BIT_USER | (write ? BIT_WRITE : 0);
	const uint32_t orMask = BIT_REFERENCED | (write ? BIT_DIRTY : 0);


	while(1) {
		uint32_t* level1 = (uint32_t*) (m_MemStart + (m_PageTableRoot & ADDR_MASK)) + (address >> 22);

		if((*level1 & reqMask) != reqMask) {
			if(pageFaultHandler(address, write)) { continue; }
			return NULL;
		}
		uint32_t* level2 = (uint32_t*) (m_MemStart + (*level1 & ADDR_MASK))
		                   + ((address >> OFFSET_BITS) & (PAGE_DIR_ENTRIES - 1));

		if((*level2 & reqMask) != reqMask) {
			if(pageFaultHandler(address, write)) { continue; }
			return NULL;
		}

		*level1 |= orMask;
		*level2 |= orMask;
		return (uint32_t*) (m_MemStart + (*level2 & ADDR_MASK) + (address & ~ADDR_MASK));
	}
}
//-------------------------------------------------------------------------------------------------