computil.c (678B)
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 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 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 }