luxos/Kernel/memory/mem-phys.c

/*
 * mem-phys.c
 *
 *  Created on: Aug 27, 2011
 *      Author: Tiberiu
 */
#include <memory-add.h>

uint32* FrameMap;
uint32 TotalFrames;
uint32 TotalMemory;
uint32 UsedFrames;

inline void ConvertIndexToFrame (uint32 index, uint32* address, uint32* offset)
{
	*address = (index >> 5);
	*offset = index & 0x1f;
}

inline uint32 ConvertFrameToIndex (uint32 address, uint32 offset)
{
	return (address<<5) | offset;
}

void MemPhSetFrame (uint32 frame, uint8 value)
{
	uint32 addr, off;
	ConvertIndexToFrame(frame, &addr, &off);

	if (value) {
		if ((FrameMap[addr] & (1<<off)) == 0) UsedFrames++;
		FrameMap[addr] |= 1<<off;
	}
	
	else {
		if (FrameMap[addr] & (1<<off)) UsedFrames--;
		FrameMap[addr] &= ~(1<<off);	
	}
}

uint32 MemPhGetFrame (uint32 frame)
{
	uint32 addr, off;
	ConvertIndexToFrame(frame, &addr, &off);

	return FrameMap[addr] & (1<<off);
}

uint32 MemPhFindFreeFrame()
{
	uint32 addr, pos;

	for (addr = 0; addr < TotalFrames >> 5; addr++)
		if (FrameMap[addr] != 0xffffffff)
		{
			for (pos = 0; (FrameMap[addr] & (1<<pos)) != 0; pos++) ;

			return ConvertFrameToIndex(addr, pos);
		}

	return 0xffffffff;
}

void MemPhAllocFrame(Page* page, uint8 isKernel, uint8 isWriteable)
{
	if ((*page & PageFrame) != 0) return;

	uint32 free = MemPhFindFreeFrame();
	if (free == 0xffffffff) {
		Panic("Mem", "%#Failed allocation free=0x%x page=0x%x\n", ColorRed, free, *page);
		return;
	}
	
	MemPhSetFrame(free, 1);
	*page |= PagePresent;
	*page |= (isKernel) ? 0 : PageUser;
	*page |= (isWriteable) ? PageWriteable : 0;
	*page |= (free<<12) & PageFrame;
}

void MemPhFreeFrame(Page* page)
{
	uint32 frame = *page & PageFrame;
	if (!frame) return;

	MemPhSetFrame(frame, 0);
	*page &= ~PageFrame;
}

void MemPhInitialize(uint32 SystemMemoryKb)
{
	TotalFrames = SystemMemoryKb >> 2;
	TotalMemory = SystemMemoryKb;

	FrameMap = (uint32*) kmalloc(sizeof(uint32) * (1 + (TotalFrames>>5)));
	memset(FrameMap, 0,  sizeof(uint32) * (1 + (TotalFrames>>5)));
	Log("Mem", "%#Started physical memory manager ok!, found %ukb\n", ColorLightGreen, SystemMemoryKb);
}

void MemPhReserveFrames (uint32 address, uint32 length)
{
	address >>= 12;
	length = (length>>12) + ((length & 0xfff) > 0);
	uint32 end = address + length;

	for (; address < end ; address++)
		MemPhSetFrame(address, 1);
}