From: Andre Noll <maan@systemlinux.org>
Date: Sat, 28 Dec 2013 17:01:40 +0000 (+0000)
Subject: bitstream: Micro-optimization.
X-Git-Tag: v0.5.3~17^2~4
X-Git-Url: http://git.tue.mpg.de/?a=commitdiff_plain;h=c526802d17412d051ffc0da4faa58255ea2982b1;p=paraslash.git

bitstream: Micro-optimization.

Subtract n_prefix right away, and don't get the next code if n becomes
non-positive. This is equivalent and saves one comparison.
---

diff --git a/bitstream.c b/bitstream.c
index ee25fffa..ce672991 100644
--- a/bitstream.c
+++ b/bitstream.c
@@ -75,14 +75,14 @@ static int build_table(struct vlc *vlc, int table_nb_bits, int nb_codes,
 	/* map codes and compute auxiliary table sizes */
 	for (i = 0; i < nb_codes; i++) {
 		GET_DATA(n, bits, i, 1);
-		GET_DATA(code, codes, i, codes_size);
 		/* we accept tables with holes */
+		n -= n_prefix;
 		if (n <= 0)
 			continue;
+		GET_DATA(code, codes, i, codes_size);
 		/* if code matches the prefix, it is in the table */
-		n -= n_prefix;
 		code_prefix2 = code >> n;
-		if (n <= 0 || code_prefix2 != code_prefix)
+		if (code_prefix2 != code_prefix)
 			continue;
 		if (n <= table_nb_bits) {
 			/* no need to add another table */