1 #include <u.h>
2 #include <libc.h>
3 #include <venti.h>
4
5 void
vtzeroextend(int type,uchar * buf,uint n,uint nn)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
vtzerotruncate(int type,uchar * buf,uint n)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 }
56