Block*
disknewblock(Disk *d, uint n)
{
uint i, j, size;
Block *b;
size = ntosize(n, &i);
b = d->free[i];
if(b)
d->free[i] = b->u.next;
else{
/* allocate in chunks to reduce malloc overhead */
if(blist == nil){
blist = emalloc(100*sizeof(Block));
for(j=0; j<100-1; j++)
blist[j].u.next = &blist[j+1];
}
b = blist;
blist = b->u.next;
b->addr = d->addr;
d->addr += size;
}
b->u.n = n;
return b;
}
void
diskrelease(Disk *d, Block *b)
{
uint i;
ntosize(b->u.n, &i);
b->u.next = d->free[i];
d->free[i] = b;
}
void
diskwrite(Disk *d, Block **bp, Rune *r, uint n)
{
int size, nsize;
Block *b;
b = *bp;
size = ntosize(b->u.n, nil);
nsize = ntosize(n, nil);
if(size != nsize){
diskrelease(d, b);
b = disknewblock(d, n);
*bp = b;
}
if(pwrite(d->fd, r, n*sizeof(Rune), b->addr) != n*sizeof(Rune))
error("write error to temp file");
b->u.n = n;
}
void
diskread(Disk *d, Block *b, Rune *r, uint n)
{
if(n > b->u.n)
error("internal error: diskread");
ntosize(b->u.n, nil);
if(pread(d->fd, r, n*sizeof(Rune), b->addr) != n*sizeof(Rune))
error("read error from temp file");
}
void
diskread(Disk *d, Block *b, Rune *r, uint n)
{
if(n > b->u.n)
panic("internal error: diskread");
ntosize(b->u.n, nil); /* called only for sanity check on Maxblock */
if(pread(d->fd, r, n*sizeof(Rune), b->addr) != n*sizeof(Rune))
panic("read error from temp file");
}
void
diskread(Disk *d, Block *b, Rune *r, uint n)
{
int tot, nr;
char *p;
if(n > b->n)
error("internal error: diskread");
ntosize(b->n, nil);
n *= sizeof(Rune);
p = (char*)r;
for(tot = 0; tot < n; tot += nr){
nr = pread(d->fd, p+tot, n-tot, b->addr+tot);
if(nr <= 0)
error("read error from temp file");
}
if(tot != n)
error("read error from temp file");
}