1 #include	"lib9.h"
2 #include	<bio.h>
3 
4 off_t
5 Bseek(Biobuf *bp, off_t offset, int base)
6 {
7 	off_t n, d;
8 
9 	switch(bp->state) {
10 	default:
11 		fprint(2, "Bseek: unknown state %d\n", bp->state);
12 		return Beof;
13 
14 	case Bracteof:
15 		bp->state = Bractive;
16 		bp->icount = 0;
17 		bp->gbuf = bp->ebuf;
18 
19 	case Bractive:
20 		n = offset;
21 		if(base == 1) {
22 			n += Boffset(bp);
23 			base = 0;
24 		}
25 
26 		/*
27 		 * try to seek within buffer
28 		 */
29 		if(base == 0) {
30 			d = n - Boffset(bp);
31 			bp->icount += d;
32 			if(d >= 0) {
33 				if(bp->icount <= 0)
34 					return n;
35 			} else {
36 				if(bp->ebuf - bp->gbuf >= -bp->icount)
37 					return n;
38 			}
39 		}
40 
41 		/*
42 		 * reset the buffer
43 		 */
44 		n = lseek(bp->fid, n, base);
45 		bp->icount = 0;
46 		bp->gbuf = bp->ebuf;
47 		break;
48 
49 	case Bwactive:
50 		Bflush(bp);
51 		n = lseek(bp->fid, offset, base);
52 		break;
53 	}
54 	bp->offset = n;
55 	return n;
56 }