return of venti

src/cmd/venti/srv/zblock.c

@@ -0,0 +1,93 @@
+#include "stdinc.h"
+#include "dat.h"
+#include "fns.h"
+
+void
+fmtzbinit(Fmt *f, ZBlock *b)
+{
+	f->runes = 0;
+	f->start = b->data;
+	f->to = f->start;
+	f->stop = (char*)f->start + b->len;
+	f->flush = nil;
+	f->farg = nil;
+	f->nfmt = 0;
+}
+
+#define ROUNDUP(p, n) ((void*)(((ulong)(p)+(n)-1)&~(ulong)((n)-1)))
+
+static char zmagic[] = "1234567890abcdefghijkl";
+
+ZBlock *
+alloczblock(u32int size, int zeroed, uint blocksize)
+{
+	uchar *p, *data;
+	ZBlock *b;
+	static ZBlock z;
+	int n;
+
+	if(blocksize == 0)
+		blocksize = 32;	/* try for cache line alignment */
+
+	n = size+32/*XXX*/+sizeof(ZBlock)+blocksize+8;
+	p = malloc(n);
+	if(p == nil){
+		seterr(EOk, "out of memory");
+		return nil;
+	}
+
+	data = ROUNDUP(p, blocksize);
+	b = ROUNDUP(data+size+32/*XXX*/, 8);
+	if(0) fprint(2, "alloc %p-%p data %p-%p b %p-%p\n",
+		p, p+n, data, data+size, b, b+1);
+	*b = z;
+	b->data = data;
+	b->free = p;
+	b->len = size;
+	b->_size = size;
+	if(zeroed)
+		memset(b->data, 0, size);
+	memmove(b->data+size, zmagic, 32/*XXX*/);
+	return b;
+}
+
+void
+freezblock(ZBlock *b)
+{
+	if(b){
+		if(memcmp(b->data+b->_size, zmagic, 32) != 0)
+			abort();
+		memset(b->data+b->_size, 0, 32);
+		free(b->free);
+	}
+}
+
+ZBlock*
+packet2zblock(Packet *p, u32int size)
+{
+	ZBlock *b;
+
+	if(p == nil)
+		return nil;
+	b = alloczblock(size, 0, 0);
+	if(b == nil)
+		return nil;
+	if(packetcopy(p, b->data, 0, size) < 0){
+		freezblock(b);
+		return nil;
+	}
+	return b;
+}
+
+Packet*
+zblock2packet(ZBlock *zb, u32int size)
+{
+	Packet *p;
+
+	if(zb == nil)
+		return nil;
+	p = packetalloc();
+	packetappend(p, zb->data, size);
+	return p;
+}
+