From dbd627d64ebcfe23b20b4b889f6ff72a2eaf3a85 Mon Sep 17 00:00:00 2001
From: Vincent Sanders <vince@kyllikki.org>
Date: Sat, 24 Sep 2016 23:40:22 +0100
Subject: convert huffman table to 32bit values

by using 32bit values instead of 8bit we make the hufman decode
require fewer memory acesses and can work on four times as many bits
of source data in one go.
---
 src/genpubsuffix.pl | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

(limited to 'src/genpubsuffix.pl')

diff --git a/src/genpubsuffix.pl b/src/genpubsuffix.pl
index 30b6689..310e004 100644
--- a/src/genpubsuffix.pl
+++ b/src/genpubsuffix.pl
@@ -124,16 +124,23 @@ sub phexbits
 	);
     my ($str) = @_;
     my @nyb = unpack "a4" x ((length($str)/4)-1) . "a*", $str;
-    my $ret = "";
+    my $ret = "   ";
     my $count = 0;
 
     do {
-	my $lo = shift @nyb;
-	my $hi = shift @nyb;
-	$ret = $ret . "0x" . $btoh{$hi} . $btoh{$lo} . ",";
+	my $a = shift @nyb;
+	my $b = shift @nyb;
+	my $c = shift @nyb;
+	my $d = shift @nyb;
+	my $e = shift @nyb;
+	my $f = shift @nyb;
+	my $g = shift @nyb;
+	my $h = shift @nyb;
+
+	$ret = $ret . " 0x" . $btoh{$h} . $btoh{$g}. $btoh{$f} . $btoh{$e}. $btoh{$d} . $btoh{$c}. $btoh{$b} . $btoh{$a} . ",";
 	$count += 1;
-	if ($count == 16) {
-	    $ret = $ret . "\n";
+	if ($count == 6) {
+	    $ret = $ret . "\n   ";
 	    $count = 0;
 	}
 
@@ -263,8 +270,8 @@ sub generate_huffman_table
     $ret .= " * Huffman coding node\n";
     $ret .= " */\n";
     $ret .= "struct hnode {\n";
-    $ret .= "    unsigned int term:1; /**< non zero if the node terminates a code */\n";
-    $ret .= "    unsigned int value:7; /**< value in node */\n";
+    $ret .= "    uint8_t term:1; /**< non zero if the node terminates a code */\n";
+    $ret .= "    uint8_t value:7; /**< value in node */\n";
     $ret .= "};\n\n";
 
     $ret .= "/**\n";
@@ -325,11 +332,11 @@ sub generate_string_table
 	    $labfullcount += 1;
 	}
     }
-    my $srounding = $bittablesize % 8;
+    my $srounding = $bittablesize % 32;
     if ($srounding > 0) {
-	# ensure bittable is a multiple of 8 bits long for byte array generation
-	$bittable .= '0' x (8 - $srounding);
-	$bittablesize += (8 - $srounding);
+	# ensure bittable is a multiple of 32 bits long for array generation
+	$bittable .= '0' x (32 - $srounding);
+	$bittablesize += (32 - $srounding);
     }
 
     print "enum stab_entities {\n";
@@ -345,7 +352,7 @@ sub generate_string_table
     print " * Domain label string table huffman encoded.\n";
     print " * " . $labcount . " labels(" . $labsize * 8 . " bits) reduced to " . $labfullcount . " labels(" . $bittablesize . " bits)\n";
     print " */\n";
-    print "static const uint8_t stab[" . ($bittablesize / 8) . "] = {\n";
+    print "static const uint32_t stab[" . ($bittablesize / 32) . "] = {\n";
     print phexbits($bittable);
     print "};\n\n";
 
-- 
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