ref: e8eed628aec56b52288625e670a097ba3bdae370
dir: /sys/src/libdraw/computil.c/
#include <u.h> #include <libc.h> #include <draw.h> /* * compressed data are seuences of byte codes. * if the first byte b has the 0x80 bit set, the next (b^0x80)+1 bytes * are data. otherwise, it's two bytes specifying a previous string to repeat. */ void _twiddlecompressed(uchar *buf, int n) { uchar *ebuf; int j, k, c; ebuf = buf+n; while(buf < ebuf){ c = *buf++; if(c >= 128){ k = c-128+1; for(j=0; j<k; j++, buf++) *buf ^= 0xFF; }else buf++; } } int _compblocksize(Rectangle r, int depth) { int bpl; bpl = bytesperline(r, depth); bpl = 2*bpl; /* add plenty extra for blocking, etc. */ if(bpl < NCBLOCK) return NCBLOCK; return bpl; }