Pavel Chromy: performance tweak of gdb_put_packet_inner() removing malloc and...

Pavel Chromy: performance tweak of gdb_put_packet_inner() removing malloc and avoiding memcpy of larger blocks of data,

git-svn-id: svn://svn.berlios.de/openocd/trunk@453 b42882b7-edfa-0310-969c-e2dbd0fdcd60

src/server/gdb_server.c

@@ -314,31 +314,27 @@ int gdb_put_packet_inner(connection_t *connection, char *buffer, int len)
 		free(debug_buffer);
 #endif
 
-		void *allocated = NULL;
-		char stackAlloc[1024];
-		char *t = stackAlloc;
-		int totalLen = 1 + len + 1 + 2;
-		if (totalLen > sizeof(stackAlloc))
+		char local_buffer[1024];
+		local_buffer[0] = '$';
+		if (len+4 <= sizeof(local_buffer))
 		{
-			allocated = malloc(totalLen);
-			t = allocated;
-			if (allocated == NULL)
-			{
-				ERROR("Ran out of memory trying to reply packet %d\n", totalLen);
-				exit(-1);
-			}
+			/* performance gain on smaller packets by only a single call to gdb_write() */
+			memcpy(local_buffer+1, buffer, len++);
+			local_buffer[len++] = '#';
+			local_buffer[len++] = DIGITS[(my_checksum >> 4) & 0xf];
+			local_buffer[len++] = DIGITS[my_checksum & 0xf];
+			gdb_write(connection, local_buffer, len);
 		}
-		t[0] = '$';
-		memcpy(t + 1, buffer, len);
-		t[1 + len] = '#';
-		t[1 + len + 1] = DIGITS[(my_checksum >> 4) & 0xf];
-		t[1 + len + 2] = DIGITS[my_checksum & 0xf];
-
-		gdb_write(connection, t, totalLen);
-
-		if (allocated)
+		else
 		{
-			free(allocated);
+			/* larger packets are transmitted directly from caller supplied buffer
+			   by several calls to gdb_write() to avoid dynamic allocation */
+			local_buffer[1] = '#';
+			local_buffer[2] = DIGITS[(my_checksum >> 4) & 0xf];
+			local_buffer[3] = DIGITS[my_checksum & 0xf];
+			gdb_write(connection, local_buffer, 1);
+			gdb_write(connection, buffer, len);
+			gdb_write(connection, local_buffer+1, 3);
 		}
 
 		if ((retval = gdb_get_char(connection, &reply)) != ERROR_OK)