1 #include <u.h>
2 #include <libc.h>
3 #include <draw.h>
4
5 /*
6 * compressed data are seuences of byte codes.
7 * if the first byte b has the 0x80 bit set, the next (b^0x80)+1 bytes
8 * are data. otherwise, it's two bytes specifying a previous string to repeat.
9 */
10 void
_twiddlecompressed(uchar * buf,int n)11 _twiddlecompressed(uchar *buf, int n)
12 {
13 uchar *ebuf;
14 int j, k, c;
15
16 ebuf = buf+n;
17 while(buf < ebuf){
18 c = *buf++;
19 if(c >= 128){
20 k = c-128+1;
21 for(j=0; j<k; j++, buf++)
22 *buf ^= 0xFF;
23 }else
24 buf++;
25 }
26 }
27
28 int
_compblocksize(Rectangle r,int depth)29 _compblocksize(Rectangle r, int depth)
30 {
31 int bpl;
32
33 bpl = bytesperline(r, depth);
34 bpl = 2*bpl; /* add plenty extra for blocking, etc. */
35 if(bpl < NCBLOCK)
36 return NCBLOCK;
37 return bpl;
38 }
39