1 #include <u.h>
2 #include <libc.h>
3 #include <venti.h>
4 
5 void
6 vtzeroextend(int type, uchar *buf, uint n, uint nn)
7 {
8 	uchar *p, *ep;
9 
10 	switch(type&7) {
11 	case 0:
12 		memset(buf+n, 0, nn-n);
13 		break;
14 	default:
15 		p = buf + (n/VtScoreSize)*VtScoreSize;
16 		ep = buf + (nn/VtScoreSize)*VtScoreSize;
17 		while(p < ep) {
18 			memmove(p, vtzeroscore, VtScoreSize);
19 			p += VtScoreSize;
20 		}
21 		memset(p, 0, buf+nn-p);
22 		break;
23 	}
24 }
25 
26 uint
27 vtzerotruncate(int type, uchar *buf, uint n)
28 {
29 	uchar *p;
30 
31 	if(type == VtRootType){
32 		if(n < VtRootSize)
33 			return n;
34 		return VtRootSize;
35 	}
36 
37 	switch(type&7){
38 	case 0:
39 		for(p = buf + n; p > buf; p--) {
40 			if(p[-1] != 0)
41 				break;
42 		}
43 		return p - buf;
44 	default:
45 		/* ignore slop at end of block */
46 		p = buf + (n/VtScoreSize)*VtScoreSize;
47 
48 		while(p > buf) {
49 			if(memcmp(p - VtScoreSize, vtzeroscore, VtScoreSize) != 0)
50 				break;
51 			p -= VtScoreSize;
52 		}
53 		return p - buf;
54 	}
55 }