mmu.h

是关于页面替换算法的代码模拟

/*
 * mmu.h	
 * Copyright (c) Inst. of Machine Intelligence at Nankai University
 */

#ifndef _MMU_H
#define	_MMU_H
#include "types.h"

#define	MEMSIZE	(4 * 1024 * 1024)

// A linear address 'la' has a three-part structure as follows:
//
// +--------10------+-------10-------+---------12----------+
// | Page Directory |   Page Table   | Offset within Page  |
// |      Index     |      Index     |                     |
// +----------------+----------------+---------------------+
//  \--- PDX(la) --/ \--- PTX(la) --/ \---- PGOFF(la) ----/
//  \----------- PPN(la) -----------/
//

// page directory index  目录索引
#define PDX(la)		((((uint32) (la)) >> PDXSHIFT) & 0x3FF)

// page table index  表索引
#define PTX(la)		((((uint32) (la)) >> PTXSHIFT) & 0x3FF)

// offset in page
#define PGOFF(la)	(((uint32) (la)) & 0xFFF)

// construct linear address from indexes and offset  构造线性地址
#define PGADDR(d, t, o)	((void*) ((d) << PDXSHIFT | (t) << PTXSHIFT | (o)))

// Page directory and page table constants.
#define NPDENTRIES	1024		// page directory entries per page directory
#define NPTENTRIES	1024		// page table entries per page table

#define PGSIZE		4096		// bytes mapped by a page
#define PGSHIFT		12		// log2(PGSIZE)

#define PTSIZE		(PGSIZE*NPTENTRIES) // bytes mapped by a page directory entry
#define PTSHIFT		22		// log2(PTSIZE)

#define PTXSHIFT	12		// offset of PTX in a linear address
#define PDXSHIFT	22		// offset of PDX in a linear address

// Page table/directory entry flags.
#define PTE_P		0x001	// Present
#define PTE_W		0x002	// Writeable
#define PTE_U		0x004	// User
#define PTE_PWT		0x008	// Write-Through
#define PTE_PCD		0x010	// Cache-Disable
#define PTE_A		0x020	// Accessed
#define PTE_D		0x040	// Dirty
#define PTE_PS		0x080	// Page Size
#define PTE_MBZ		0x180	// Bits must be zero

// The PTE_AVAIL bits aren't used by the kernel or interpreted by the
// hardware, so user processes are allowed to set them arbitrarily.
#define PTE_AVAIL	0xE00	// Available for software use

// Only flags in PTE_USER may be used in system calls.
#define PTE_USER	(PTE_AVAIL | PTE_P | PTE_W | PTE_U)

// address in page table entry
#define PTE_ADDR(pte)	((phyaddr_t) (pte) & ~0xFFF)

#define	PAGING	(1 << 31)

int	write_memory(viraddr_t va, char* buf, int size);
int	read_memory(viraddr_t va, char* buf, int size);
void handler();                                       //缺页中断函数
#endif