/*
* convert malloced or non-malloced buffer to a Block.
* used to build custom Block allocators.
*
* buf must be at least blocksize(usable) bytes.
*/
Block *
mem2block(void *buf, ulong usable, int malloced)
{
Block *b;
if(buf == nil)
return nil;
b = (Block *)buf;
b->next = nil;
b->list = nil;
b->free = 0;
b->flag = 0;
b->ref = 0;
b->magic = Bmagic;
_xinc(&b->ref);
/* align start of data portion by rounding up */
b->base = (uchar*)ALIGNUP((ulong)b + sizeof(Block));
/* align end of data portion by rounding down */
b->lim = (uchar*)b + (malloced? msize(b): blocksize(usable));
b->lim = (uchar*)((ulong)b->lim & ~(BLOCKALIGN-1));
/* leave sluff at beginning for added headers */
b->wp = b->rp = b->lim - ALIGNUP(usable);
if(b->rp < b->base)
panic("mem2block: b->rp < b->base");
if(b->lim > (uchar*)b + (malloced? msize(b): blocksize(usable)))
panic("mem2block: b->lim beyond Block end");
return b;
}
static void
rxfreeb(Block *b)
{
/* freeb(b) will have previously decremented b->ref to 0; raise to 1 */
_xinc(&b->ref);
b->wp = b->rp =
(uchar*)((uintptr)(b->lim - Rxblklen) & ~(Bufalign - 1));
assert(((uintptr)b->rp & (Bufalign - 1)) == 0);
b->free = rxfreeb;
ilock(&freeblocks);
b->next = freeblocks.head;
freeblocks.head = b;
iunlock(&freeblocks);
}
static void
inccnt(Ref *r)
{
_xinc(&r->ref);
}