From: Michael Gernoth <michael@gernoth.net>
Date: Mon, 2 Feb 2009 23:27:09 +0000 (+0100)
Subject: add comments about compression algorithm implementation
X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/rsbs2/commitdiff_plain/1d359f151c5a8943607207ea24d1092bd2e08ead

add comments about compression algorithm implementation
---

diff --git a/rsb-lz.c b/rsb-lz.c
index c23dd5a..4dddd9b 100644
--- a/rsb-lz.c
+++ b/rsb-lz.c
@@ -101,34 +101,42 @@ void write_byte(unsigned char byte, struct data_out_s *data_out)
 void lz_expand(struct data_in_s *data_in, struct data_out_s *data_out)
 {
 	unsigned int pos;
-	unsigned int offset;
+	unsigned int wordoffset;
 	unsigned int i;
 	unsigned char byte;
-	unsigned int num;
+	unsigned int wordlen;
 	unsigned char buf[1024];
 
 	pos = 1;
 
 	while (1) {
 		while (1) {
+			/* Compressed/uncompressed? */
 			if (get_next_bit(data_in) == 0)
 				break;
 
+			/* Uncompressed byte */
 			byte = get_next_bits(data_in, 8);
 
 			write_byte(byte, data_out);
+
+			/* Save byte in buffer, to be reused later */
 			buf[pos] = byte;
 			pos = (pos + 1) & 0x3ff;
 		}
 
-		offset = get_next_bits(data_in, 0x0a);
-		if(offset == 0)
+		/* offset for start of dictionary word */
+		wordoffset = get_next_bits(data_in, 0x0a);
+		if(wordoffset == 0)
 			return;
 
-		num = get_next_bits(data_in, 0x04) + 1;
-		for (i = 0; i <= num; i++) {
-			byte = buf[(offset + i) & 0x3ff];
+		/* length of dictionary word used */
+		wordlen = get_next_bits(data_in, 0x04) + 1;
+		for (i = 0; i <= wordlen ; i++) {
+			/* lookup dictionary byte */
+			byte = buf[(wordoffset + i) & 0x3ff];
 			write_byte(byte, data_out);
+			/* Save byte in buffer, to be reused later */
 			buf[pos] = byte;
 			pos = (pos + 1) & 0x3ff;
 		}