Make mkbundle bundle assemblies a lot faster.

Preallocate the 256 different lines we might write to the assembly file
instead of allocating several strings for every line.

With compression mkbundle is about twice as fast now (since compression
speed hasn't changed), without compression it's 5-10x faster, depending
on the number of assemblies to embed.

mcs/tools/mkbundle/mkbundle.cs

@@ -201,6 +201,26 @@ static void WriteSymbol (StreamWriter sw, string name, long size)
 		}
 	}
 
+	static string [] chars = new string [256];
+
+	static void WriteBuffer (StreamWriter ts, Stream stream, byte[] buffer)
+	{
+		int n;
+
+		// Preallocate the strings we need.
+		if (chars [0] == null) {
+			for (int i = 0; i < chars.Length; i++)
+				chars [i] = string.Format ("\t.byte {0}\n", i.ToString ());
+		}
+
+		while ((n = stream.Read (buffer, 0, buffer.Length)) != 0) {
+			for (int i = 0; i < n; i++)
+				ts.Write (chars [buffer [i]]);
+		}
+
+		ts.WriteLine ();
+	}
+
 	static void GenerateBundles (ArrayList files)
 	{
 		string temp_s = "temp.s"; // Path.GetTempFileName ();
@@ -244,12 +264,13 @@ static void GenerateBundles (ArrayList files)
 
 				Stream stream = File.OpenRead (fname);
 
+				// Compression can be parallelized
 				long real_size = stream.Length;
 				int n;
 				if (compress) {
 					MemoryStream ms = new MemoryStream ();
 					DeflaterOutputStream deflate = new DeflaterOutputStream (ms);
-					while ((n = stream.Read (buffer, 0, 8192)) != 0){
+					while ((n = stream.Read (buffer, 0, buffer.Length)) != 0){
 						deflate.Write (buffer, 0, n);
 					}
 					stream.Close ();
@@ -259,13 +280,8 @@ static void GenerateBundles (ArrayList files)
 				}
 
 				WriteSymbol (ts, "assembly_data_" + encoded, stream.Length);
-
-				while ((n = stream.Read (buffer, 0, 8192)) != 0){
-					for (int i = 0; i < n; i++){
-						ts.Write ("\t.byte {0}\n", buffer [i]);
-					}
-				}
-				ts.WriteLine ();
+
+				WriteBuffer (ts, stream, buffer);
 
 				if (compress) {
 					tc.WriteLine ("extern const unsigned char assembly_data_{0} [];", encoded);
@@ -288,11 +304,7 @@ static void GenerateBundles (ArrayList files)
 					Console.WriteLine (" config from: " + fname + ".config");
 					tc.WriteLine ("extern const unsigned char assembly_config_{0} [];", encoded);
 					WriteSymbol (ts, "assembly_config_" + encoded, cf.Length);
-					while ((n = cf.Read (buffer, 0, 8192)) != 0){
-						for (int i = 0; i < n; i++){
-							ts.Write ("\t.byte {0}\n", buffer [i]);
-						}
-					}
+					WriteBuffer (ts, cf, buffer);
 					ts.WriteLine ();
 					config_names.Add (new string[] {aname, encoded});
 				} catch (FileNotFoundException) {
@@ -312,12 +324,7 @@ static void GenerateBundles (ArrayList files)
 				tc.WriteLine ("extern const char system_config;");
 				WriteSymbol (ts, "system_config", config_file.Length);
 
-				int n;
-				while ((n = conf.Read (buffer, 0, 8192)) != 0){
-					for (int i = 0; i < n; i++){
-						ts.Write ("\t.byte {0}\n", buffer [i]);
-					}
-				}
+				WriteBuffer (ts, conf, buffer);
 				// null terminator
 				ts.Write ("\t.byte 0\n");
 				ts.WriteLine ();
@@ -335,13 +342,7 @@ static void GenerateBundles (ArrayList files)
 				tc.WriteLine ("extern const char machine_config;");
 				WriteSymbol (ts, "machine_config", machine_config_file.Length);
 
-				int n;
-				while ((n = conf.Read (buffer, 0, 8192)) != 0){
-					for (int i = 0; i < n; i++){
-						ts.Write ("\t.byte {0}\n", buffer [i]);
-					}
-				}
-				// null terminator
+				WriteBuffer (ts, conf, buffer);
 				ts.Write ("\t.byte 0\n");
 				ts.WriteLine ();
 			}