buffer_init.c

阿基米德操作系统的源代码

//////////////////////////////////////////////////////////////////////////
#include "general.h"

#include "hd_info_struct.h"
#include "dir_entry.h"
#include "msdos_dir_entry.h"
#include "d_inode.h"
#include "m_inode.h"
#include "buffer_head.h"
#include "fat_cache.h"
#include "file.h"
#include "hd_request_struct.h"
#include "super_block.h"

#include "common_head.h"
//////////////////////////////////////////////////////////////////////////

void buffer_init(void)
{
	struct buffer_head * temp_start = (struct buffer_head *) BUFFER_START;
	void               * temp_end = (void *) BUFFER_END;
	int                  temp_i,temp_bufnum;

	////////////////////////////////////////////////////////////////
	temp_bufnum = (BUFFER_END - BUFFER_START) / (BLOCK_SIZE + 32);
	temp_end	= temp_end - temp_bufnum * BLOCK_SIZE;

	start_buffer				= temp_start;
	for (temp_i = 0; temp_i < temp_bufnum; temp_i++)
	{
		temp_start->b_data		= (char *) temp_end;
		temp_start->b_dev		= 0;
		temp_start->b_blocknr	= 0;
		temp_start->b_uptodate	= 0;
		temp_start->b_dirt		= 0;
		temp_start->b_count		= 0;
		temp_start->b_lock		= 0;
		temp_start->b_prev		= NULL;
		temp_start->b_next		= NULL;
		temp_start->b_prev_free	= temp_start - 1;
		temp_start->b_next_free	= temp_start + 1;
		
		temp_start++;
		temp_end  = temp_end + BLOCK_SIZE;
	}
	end_buffer					= temp_start;

	current_buffer				= start_buffer;
	sys_buffer					= start_buffer;	

	for (temp_i = 0; temp_i < 17; temp_i++)
	{
		sys_buffer->b_blocknr	= temp_i;
		sys_buffer->b_uptodate	= 0x80;
		sys_buffer->b_count		= 1;
		sys_buffer->b_prev_free	= sys_buffer;
		sys_buffer->b_next_free = sys_buffer;
		sys_buffer++;
	}

	temp_start--;
	sys_buffer->b_prev_free		= temp_start;
	temp_start->b_next_free		= sys_buffer;

	free_list					= sys_buffer;

	nr_buffers = temp_bufnum;
	////////////////////////////////////////////////////////////////

	for (temp_i = 0 ; temp_i < NR_HASH ; temp_i++)
		hash_table[temp_i] = NULL;

	return;
}