emumem.h

這是一個arm模擬器 以C++實做 主要模擬ARM9架構

		memory_fault_t get_last_fault() const {return last_fault;}
		target_addr_t  get_last_faddr() const {return last_faddr;}

	private:

		/* a page table entry */
		typedef struct memory_page_table_entry_t
		{
			unsigned int flag;
			byte_t *ptr;
		} memory_page_table_entry_t;

		// get the permission bits of a page
		unsigned int get_page_permission(target_addr_t addr) const; 
		void set_page_permission(target_addr_t addr, unsigned int perm);

		// mark a page as available or unavailable
		void mark_page_available(target_addr_t addr, unsigned int perm);
		void mark_page_unavailable(target_addr_t addr);

		// remap and unmap a page, page is unavailable after successful unmap
		void remap_page(target_addr_t addr,
						memory_ext_interface *mif, unsigned int perm);
		void unmap_page(target_addr_t addr);


		/* test if an address crosses page boundary, size < MEM_PAGE_SIZE */
		bool cross_page_boundary(target_addr_t addr, unsigned int size) const
		{
			return (addr & (MEMORY_PAGE_SIZE - 1)) > (MEMORY_PAGE_SIZE - size);
		}

		/* some useful utilities */
		target_addr_t align_to_page_boundary(target_addr_t addr) const
		{
			return addr & ~(MEMORY_PAGE_SIZE-1);
		}

		byte_t swap(byte_t val) const
		{
			return val;
		}

		hword_t swap(hword_t val) const
		{
			return (val>>8) | (val<<8);
		}

		word_t swap(word_t val) const
		{
			return (val>>24) | ((val>>8)&0xFF00) |
				   ((val&0xFF00)<<8) | (val<<24) ;
		}

		dword_t swap(dword_t val) const
		{
			return ((dword_t)swap((word_t)val)<<32) |
				    (dword_t)swap((word_t)(val>>32));
		}

		/* storage allocated for a normal page */
		bool page_allocated(const memory_page_table_entry_t *pte) const 
		{
			return ((pte->flag & MEMORY_PAGE_SLOW)==0);
		}

		/* storage allocated for a normal page */
		bool page_allocated(target_addr_t addr) const 
		{
			target_addr_t page_index = addr >> MEMORY_PAGE_SIZE_BITS;
			return ((page_table[page_index].flag & MEMORY_PAGE_SLOW)==0);
		}

		/* page remapped */
		bool page_remapped(const memory_page_table_entry_t *pte) const 
		{
			return (pte->flag & MEMORY_PAGE_REMAPPED);
		}

		/* page remapped */
		bool page_remapped(target_addr_t addr) const 
		{
			target_addr_t page_index = addr >> MEMORY_PAGE_SIZE_BITS;
			return (page_table[page_index].flag & MEMORY_PAGE_REMAPPED);
		}

		const memory_page_table_entry_t *get_page(target_addr_t addr) const
		{
			target_addr_t page_index = addr >> MEMORY_PAGE_SIZE_BITS;
			return page_table + page_index;
		}

		memory_page_table_entry_t *get_page(target_addr_t addr)
		{
			target_addr_t page_index = addr >> MEMORY_PAGE_SIZE_BITS;
			return page_table + page_index;
		}

		template<class T>
		T read_base(target_addr_t addr)
		{
#ifdef CHECK_PAGE_BOUNDARY
			/* if crossing page boundary */
			if (sizeof(T) > 1 && cross_page_boundary(addr, sizeof(T)))
				return read_slow<T>(addr);
#endif

			const memory_page_table_entry_t *pte = get_page(addr);
			/* if empty (not allocated), remapped, bad, or not readable */
			if (!(pte->flag & MEMORY_PAGE_READABLE))
				return read_slow<T>(addr);

#if WORDS_BIGENDIAN==TARGET_LITTLE_ENDIAN
			return swap(*reinterpret_cast<T *>(pte->ptr + addr));
#else
			return *reinterpret_cast<T*>(pte->ptr + addr);
#endif
		}

		template<class T>
		memory_fault_t read_base(target_addr_t addr, T *pval)
		{
#ifdef CHECK_PAGE_BOUNDARY
			/* if crossing page boundary */
			if (sizeof(T) > 1 && cross_page_boundary(addr, sizeof(T)))
				return read_slow(addr, pval);
#endif

			const memory_page_table_entry_t *pte = get_page(addr);
			/* if empty (not allocated), remapped, bad, or not readable */
			if (!(pte->flag & MEMORY_PAGE_READABLE))
				return read_slow(addr, pval);

#if WORDS_BIGENDIAN==TARGET_LITTLE_ENDIAN
			*pval = swap(*reinterpret_cast<T *>(pte->ptr + addr));
#else
			*pval = *reinterpret_cast<T*>(pte->ptr + addr);
#endif
			return MEM_NO_FAULT;
		}

		template<class T>
		memory_fault_t write_base(target_addr_t addr, T value)
		{
#ifdef CHECK_PAGE_BOUNDARY
			/* if crossing page boundary */
			if (cross_page_boundary(addr, sizeof(T)))
				return write_slow(addr, value);
#endif

			const memory_page_table_entry_t *pte = get_page(addr);
			/* if empty (not allocated), remapped, bad, or not writable */
			if (!(pte->flag & MEMORY_PAGE_WRITABLE))
				return write_slow(addr, value);

#if WORDS_BIGENDIAN==TARGET_LITTLE_ENDIAN
			*reinterpret_cast<T *>(pte->ptr + addr) = swap(value);
#else
			*reinterpret_cast<T *>(pte->ptr + addr) = value;
#endif
			return MEM_NO_FAULT;
		}

		/* slow but full featured memory acecss interface
		 * overloading is safer here since these are private
		 */
		memory_fault_t write_slow(target_addr_t addr, dword_t value);
		memory_fault_t write_slow(target_addr_t addr, word_t  value);
		memory_fault_t write_slow(target_addr_t addr, hword_t value);
		memory_fault_t write_slow(target_addr_t addr, byte_t  value);

		memory_fault_t read_slow(target_addr_t addr, dword_t *pval);
		memory_fault_t read_slow(target_addr_t addr, word_t  *pval);
		memory_fault_t read_slow(target_addr_t addr, hword_t *pval);
		memory_fault_t read_slow(target_addr_t addr, byte_t  *pval);

		/* these are the basis of the above _slow functions,
		 * their implementation is hidden in emumem.cpp file
		 */
		template <class T>
		memory_fault_t read_slow_base(target_addr_t addr, T *pval);

		template <class T>
		memory_fault_t write_slow_base(target_addr_t addr, T val);

		template <class T>
		T read_slow(target_addr_t addr)
		{
			T val;
			read_slow(addr, &val);
			return val;
		}

		/* simple block access functions */
		memory_fault_t read_block_within_page(void *buf,
			target_addr_t addr, unsigned int size, unsigned *psize);
		memory_fault_t write_block_within_page(void *buf,
			target_addr_t addr, unsigned int size, unsigned *psize);
		memory_fault_t set_block_within_page(target_addr_t addr,
			byte_t value, unsigned int size, unsigned *psize);

		/* allocate and free space for a page
		 * when memory runs out, allocate_page returns NOMEMORY_FAULT
		 */
		memory_fault_t allocate_page(memory_page_table_entry_t *pte);
		void free_page(memory_page_table_entry_t *pte);

		/* returns non-zero if there is a permission fault */
		memory_fault_t check_page_permission(target_addr_t addr,
				unsigned int perm) const;

		memory_fault_t check_page_permission
				(const memory_page_table_entry_t *pte,
				unsigned int perm) const;

		/* Address translation, NULL if remapped or error.
		 * The function is created for MMU's use.
		 * The return value does not point to the actually storage.
		 * Instead, ptr+addr is the actual address.
		 * See allocate page for details.
		 */
		byte_t *translate(target_addr_t addr)
		{
			memory_fault_t fault;
			memory_page_table_entry_t *pte = get_page(addr);

			/* if normal */
			if (page_allocated(pte)) return pte->ptr;

			/* normal page without space */
			if (pte->flag & MEMORY_PAGE_EMPTY) 
			{
				if ((fault = allocate_page(pte)) != MEM_NO_FAULT)
					report_fault(fault, addr);

				return pte->ptr; //ptr is NULL when allocate fails
			}

			/* IO remap, bad address */
			return NULL;
		}

		/* report a fault, raise a signal it fault_sig is not -1 */
		void report_fault(memory_fault_t f, target_addr_t addr);

		/* page table */
		memory_page_table_entry_t page_table[MEMORY_PAGE_TABLE_SIZE];

		/* stats information */
		unsigned int page_count;	

		/* signal on fault */
		int fault_sig;

		/* stores the information of the last fault*/
		memory_fault_t last_fault;
		target_addr_t last_faddr;

		friend class arm_mmu;

};

} /* namespace simit */

#endif