file-block.c

用于汇编领域的,运用于OS的MAIN函数.基于硬件基础的源代码

#include "fs.h"
void FB_dump(char *blk){
   int i; unsigned long *buf;
   buf=(unsigned long *)blk;
   for(i=0;i<12;i++)
      printk("%x ",buf[i]);
}
void FBTable_dump_blk(int n){
// dump fbtable.arr[n].blk
   printk("dumping block %d\n",n);
   FB_dump(FBTable_find_block(n));
}

void FBTable_init(){
// blk_nr=-1 means no block
   int i;
   for(i=0;i<MAX_FBT;i++)
      fbtable.arr[i].blk_nr=-1;
}

int FBTable_find_empty_block_frame(){
   int i;
   for(i=0;i<MAX_FBT;i++)
      if (fbtable.arr[i].blk_nr == -1) return i;
   panic("file block table full\n");
}

char * FBTable_retrieve_block_from_disk(int bno){
// retrieve block bno from disk, put it in fbtable, and return the pointer
   char temp[BLKSIZE]; int n;
   // read
   ReadRelativeSector(bno, temp, temp);
   // put it in fbtable
   n=FBTable_find_empty_block_frame();
   printk("FBTable_retrieve_blk_from_disk. read blk %d into fbtable[%d]\n",bno,n);
   memcpy(fbtable.arr[n].blk, temp, BLKSIZE);
   fbtable.arr[n].blk_nr=bno;
   return fbtable.arr[n].blk;
}

char * FBTable_find_block(int bno){
// return file block pointer whose block num is bno
   int i;
   for(i=0;i<MAX_FBT;i++)
      if (fbtable.arr[i].blk_nr == bno) 
	     return fbtable.arr[i].blk;
   panic("FBTable_find_block:no such block:%d\n",bno);
}

char * FBTable_get_block(int bno){
// return file block pointer whose block num is bno
   int i;
   for(i=0;i<MAX_FBT;i++)
      if (fbtable.arr[i].blk_nr == bno) 
	     return fbtable.arr[i].blk;
   // couldn't find. get it from disk
   return FBTable_retrieve_block_from_disk(bno);
}
/*   
void FBTable_read_fblock_from_disk(int bn){
// get block bn from floppy disk. put it in fbt
   int x;
   x=FBTable_find_empty_block_frame();
   fbtable.arr[x].blk_nr = bn;
   fbtable.arr[x].dirty = 0; // not changed yet
   ReadRelativeSector(bn, fbtable.arr[x].blk, fbtable.arr[x].blk);
}
*/
void FBTable_flush_file_blocks(){
// flush all dirty blocks back to disk
   int i;
   int bn; char * blk; int dirty;
   for(i=0;i<MAX_FBT;i++){
      bn = fbtable.arr[i].blk_nr;
	  blk = fbtable.arr[i].blk;
	  dirty = fbtable.arr[i].dirty;
      //if (bn != -1 && dirty==1)
      if (bn != -1) // for now flush all has-data blocks. dirty should be
	                // implemented later
	      WriteRelativeSector(bn, blk, blk);
   }
}