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#include "types.h"
#include "param.h"
#include "x86.h"
#include "mmu.h"
#include "proc.h"
#include "defs.h"
#include "spinlock.h"
#include "buf.h"
struct buf buf[NBUF];
struct spinlock buf_table_lock;
void
binit(void)
{
initlock(&buf_table_lock, "buf_table");
}
struct buf *
getblk()
{
int i;
acquire(&buf_table_lock);
// XXX need to lock the block even if not caching, to
// avoid read modify write problems.
while(1){
for(i = 0; i < NBUF; i++){
if((buf[i].flags & B_BUSY) == 0){
buf[i].flags |= B_BUSY;
release(&buf_table_lock);
return buf + i;
}
}
sleep(buf, &buf_table_lock);
}
}
struct buf *
bread(uint dev, uint sector)
{
void *c;
struct buf *b;
extern struct spinlock ide_lock;
b = getblk();
acquire(&ide_lock);
c = ide_start_rw(dev & 0xff, sector, b->data, 1, 1);
sleep (c, &ide_lock);
ide_finish(c);
release(&ide_lock);
return b;
}
void
bwrite(uint dev, struct buf *b, uint sector)
{
void *c;
extern struct spinlock ide_lock;
acquire(&ide_lock);
c = ide_start_rw(dev & 0xff, sector, b->data, 1, 0);
sleep (c, &ide_lock);
ide_finish(c);
release(&ide_lock);
}
void
brelse(struct buf *b)
{
if((b->flags & B_BUSY) == 0)
panic("brelse");
acquire(&buf_table_lock);
b->flags &= ~B_BUSY;
wakeup(buf);
release(&buf_table_lock);
}
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