Initial import.

src/libdraw/computil.c

@@ -0,0 +1,38 @@
+#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;
+}