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Java programming

After just over 3 years of programming in Java, I still haven’t sussed out how to actually open up a basic IDE and start a simple UI project from scratch.

This I know from installing Netbeans. Which I’ve used before to create a dedicated server so that client devices can receive images created using Java AWT libraries. That was easy, create a TCP listening thread, accept connections, return renderings of bitmaps in compressed PNG format. Easy.

I’ve also created (which was a UI app) a program that sniffs the UDP broadcast of the IPTV/Digital Signage server (which I wrote), and opens up a custom web interface from the server without knowing the IP address. That was easy with the help of a couple of references from the web. It turned out to be quite a small program in the end and hardly any effort in it.

Even after Android development, writing games and even using FFMpeg to write a media player using the NDK.

I simply just wanted to write (using the accumulated knowledge of Java) a simple multi window/dialog application on my laptop. Wow… It still amazes me how I got through all the previous software developing. Maybe on an evening, I’m just not that focused. But I’m not giving in.

Java may not have the power of C, but it does have a lot that can be used as I’ve mentioned above. I’m finding it simple to handle threading and AWT bitmaps, etc. All I need now is to be able to setup up a display in a window (GL or raster, whichever is the quickest to begin with) and I’ll be happy.

Qt is simple enough for both openGL and normal UI stuff. So now I want to do the same with Java. So far without the UI stuff, I can run anything, ie server side from Java, but UI stuff I’ll just have to persevere with.

I’ll get there. Nighttime coding was something I always used to do. Going to bed when I realised the sun was poking its head up in the morning.

If I can keep this up (future plans)

Many years ago I started building my online profile and populated my old website with lots of content. Unfortunately, all that has gone despite trying to get in touch with the hosting company. It was free hosting.

Now my hosting is paid for so that gives me something if times get dark and finances get short.

The boiler-plate code for a 3D online demo is almost complete but am I hell staying up past 11pm when I have to be up at 6am in the morning.

I have all next week off, so when I am not out on my motorbike getting lost around the country, which I can’t do much anyway until I get paid next, I’ll be at home building up some showcase examples. These I will plan on hosting using webGL. I’ve got a lot of ideas and I plan on getting a good few of them done next week.

My future depends on it now, because I haven’t got the pennies to fill up my tank.

Dev updates for May 2017

There’s actually a shed load of updates, but I doubt I’ll get them all done tonight.

I now have a Java server running which provides Java specific rendering using AWT and other java standard features.
DVB-S is easy.
Using FFMpeg as a general media player for both IPTV/UDP and file/network based streams, including pause and seek.
Finally got round to installing 4 OS’s on my main laptop. Windows 10 and 3 other Linux OS’s.
Manually re-installed a HP tablet with Android OS from scratch.
Erm… Blank…

Stuff to do:

Loads… I’ll remember them probably tomorrow.
Add more code to this website.

Home server is offline… for now

My home PC has been re-installed, dual booting with Linux and Windows 7. My plan is to keep the web server running whether I boot up in either OS.

I’m working on it.

Time to get personal…

With a long weekend coming up due to the Easter break and a lot of ideas in my head, I’ve decided to start some more experiments with some serious coding.

Various online profiles will be updated too.

Watch this space…

!false is funny because it's true

New laptop and Linux Mint dual boot

A few weeks ago I bought a laptop, a Dell Precision 4500, i7 2Ghz, 4Gb memory, Quadro 1800M and a 320Gb hard disk, pre-installed with Windows 7.

The first thing I did was to shrink the volume which gave me about 130Gb which I installed Linux Mint 18.3. The dual boot worked fine until I updated the nVidia drivers and lost the resolution of 1920×1080. This is after installing everything, all my programming stuff, 3D stuff, etc. I tried the workarounds online with no joy, I was losing performance.

Anyway, I had a 9.5mm draw replacement which I could remove the DVD drive and put in my SSD drive.

The first three installs of Linux and it freezing randomly, plus sussing out out why in the end the GRUB bootloader was on the wrong drive, I finally figured a way to get it up and running. Initially, after reading that on an SSD you don’t need a swap partition, the last install I went back to the swap partition with the install. And it is now working.

I’ve yet to update the nVidia drivers which I will do sometime soon.

At the moment, I can boot into Windows off the normal HD and Linux off my SSD. It runs sweet. Programming stuff is installed but not yet used. I need a long holiday to really get this beast going. The graphics on this laptop actually run better than my PC (i7 4790, nVidia GTX 730).

The only thing that slows this laptop down is the hard drive and Windows.

Maybe tomorrow I will actually bravely update the nVidia drivers for Linux Mint because I soon want to start experimenting with 3D graphics API’s for desktop and mobile again. And as usual I wish I had just a minute more time to focus on my personal projects.

Reinstallation done

All done and only got a few bits to install now. And the good news is that the tomcat server now works again.

Phew! I can get back to the 3D stuff again.

Re-install PC

I’ve recently upgraded from Linux Mint 17.3 to 18 and although everything else is working just fine, the tomcat server doesn’t. The client side of a web application works but there’s no joy from the server side so zero RPC calls are working.

A fresh install will be good anyway as it will clear a lot of junk out.

Ah well, should be about 30 minutes to an hour installing most of my software back. It’s handy having a nice 480Gb SSD and decent download speeds.

TCP internet communication notes

Now that I’ve got that working over the internet, there are many things that this kind of thing can be used for. Most of them are obvious, but a few I’ve had in mind for some time now.

For an app running on a device, it can download media specific to that device. ie, scaled to fit the resolution.
A device can be checked for memory and storage space limits and then download media that is optimised for the device to run the app.
Even for 3D apps, a device can request 3D meshes optimised to run on that device depending on the graphics capabilities. This can be useful for animated meshes with lots of vertices. The server can reduce the size of the mesh and the animation.
If a device can output in surround sound then audio can requested that supports surround sound.
Multiplayer games. The server can receive players positions and then send the local information back out to other devices.
Devices can also send data to the server. This can be for a multitude of reasons. ie. a players profile picture or for audio communication between players.

As you can see from the above, there’s no limit to what a running server can do.

One thing I will have to do soon is to handle brute force attacks on the server. This happens when a DoS (Denial Of Service) attack occurs, which is a deliberate attack in which lots of data is sent to the server continuously. The simple way around this is to have a damn good fast CPU in the server and to record IP’s that are connecting. If an IP is not requesting the usual data and has attempted X amount of times then it goes onto a block list. Each connection attempt will first check the block list and instantly close the connection if that IP is blocked so that no further time is spent processing the connections request. At this current moment in time the Intel Xeon and the latest Intel i7’s have the cores that could handle DoS attacks.

Multiplayer games requires a whole new line of thinking, especially when they’re real time. Band width can be a pain, but there are many ways to get around this. In one of the above notes, I mentioned ‘local’ data. This comes into play when a players device only needs to receive the local updates in the surrounding area. Although the server will handle all players, it will only send each device its local data.

Anyway, that’s me done for now while I think of what to do next.

Any ideas, then get in touch.

Testing out TCP server over the web (my IoT stuff)

So I have this idea where I can take photos on my phone or save images from the web and then send them directly to my PC.

I’m currently using a Sky router in which I have enabled a port redirect to my PC. That’s all working. And I’ve got an external web address which re-routes to my PC also. That’s all working as I can host a website on my PC and access from outside.

The first pitfall was I started a console application in Qt to be a TCP server, but, deploying Qt applications to anywhere can be a huge pain in the butt.

So now I’ve decided to pick between a Java server or a C/C++ server. The issue I will have with a standard C/C++ server is image handling when it comes to working with them in the future, whereas Java has built in Bitmap libraries. Although I could add a 3rd party library to get around this, Java has lots of other libraries.

The other issue is speed. C/C++ has raw speed and that it. But because its a server, speed shouldn’t really be an issue for most things.

I’ve already successfully got the address of my PC over the internet and in the past had a basic TCP communication test working. This time it’s for real.

Okay, I’ll try out a Java project and see how it goes.

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Assembler PRNG (from Java to Asm)

So, I had a perfectly working PRNG in Java like this:

public class WLPRNG {
    
    long seed;
    
    public WLPRNG(long seed) { this.seed = seed; }
    
    public int nextInt() {
        long result = seed + 0x123defca;
        result = Long.rotateLeft(result, 19);
        result += 0xbead6789;
        result *= 0x1234567c;
        
        int temp = (int)result;
        
        result ^= 0x5ecdab73;
        result = Long.rotateLeft(result, 48);
        
        if (temp % 4 == 0) result *= 0x87650027;
        
        result += 13;
        seed = result;
        
        return (int)result;
    }

    public byte nextByte() {
        return (byte)nextInt();
    }
}

And I thought I’d test out the Assembler version like this:

; random number generator to be used in crypto transmission
; of sensitive data over the internet

; WLGfx 2017-Nov-19

        section .text

global  main

extern  printf

srand:  mov     [seed],rax                      ; set random seed
        ret

arand:  mov     rax,[seed]                      ; get seed
        mov     rbx,qword 0x023defca321acfed
        add     rax,rbx                         ; add 64 bit value
        rol     rax,19                          ; rotate bits
        mov     rbx,qword 0xbead6789
        add     rax,rbx                         ; another add
        imul    rax,qword 0x1234567c            ; a multiple this time
        mov     rbx,rax                         ; copy into rbx
        xor     rax,qword 0x5ecdab73            ; flip some bits
        rol     rax,48                          ; rotate bits again
        mov     rcx,rax                         ; copy to rcx
        and     rax,0x3                         ; mask and test with 0
        jnz     .notz                           ; 25% chance of other ops
        mov     rax,rbx
        add     rcx,rax
        mov     rbx,qword 0x87650027
        imul    rax,rbx
        jmp     .cont
.notz   mov     rax,rcx                         ; back into rax
.cont   mov     [seed],rax                      ; store into seed
        and     rax,0xff                        ; return byte value only
        ret

main:   mov     rax,9                           ; set seed
        call    srand

        mov     dword[lc],10                    ; set loop counter

.loop   call    arand                           ; get random byte

        push    rbp                             ; stack frame
        mov     rsi,rax                         ; random number
        mov     rdi,pf_msg                      ; format string
        xor     rax,rax                         ; 0
        call    printf                          ; call printf
        pop     rbp                             ; stack frame

        sub     dword[lc],1                     ; dec loop counter
        jnz     .loop
        
        ret

        section .data

seed    dq      0,0,0,0                         ; random seed value 64 bit
lc      dd      10                              ; loop counter

pf_msg  db      "Number: 0x%02x",10,0

Using the build script:

#!/bin/bash
nasm -f elf64 random.asm
gcc -o random random.o

Gives a sample output of:

 ~/dev/asm/tests $ ./buildrand.sh 
 ~/dev/asm/tests $ ./random 
Number: 0xe0
Number: 0x5b
Number: 0xca
Number: 0x7c
Number: 0xfc
Number: 0x2d
Number: 0x79
Number: 0xa5
Number: 0x62
Number: 0x7f

All I need to do now is to be able to link directly to C and C++ code. I’m currently reading up on threading in assembler, but it looks like the standard pthreads are just the same really.

There’s lot’s of potential for using assembler.

X86_64 printf 64 bit assembler test

So, I wanted to start playing about with assembler again. Mainly so I could use it for data encryption over the internet. Here’s a simple sample of printing 64 bit numbers as hex.

section .text
global  main

extern  printf

; use printf to print 64 bit hex string

_test:  push    rbp

        mov     rsi,0x1234567890abcdef
        mov     rdi,pf_msg
        xor     rax,rax
        call    printf

        pop     rbp
        
        ret

main:   call    _test
        
        mov     edx,len
        mov     ecx,msg
        mov     eax,4
        int     128
        
        ;mov     eax,1
        ;int     128
        
        xor     rax,rax
        ret

section .data

msg     db      "Hello world!",10
len     equ     $ - msg

; some testing stuff

pf_msg  db      "Register = %016llx", 10, 0

I set up a simple script to build the executable.

#!/bin/bash
nasm -f elf64 test.asm
gcc -o test test.o

And the output is just…

Register = 1234567890abcdef
Hello world!

The weekends plans

Yay! Friday finally came around and it’s the evening. I’m currently on a wind down, my body is aching and I’m mentally and physically zapped out. And that’s why I’m writing an update.

Over this last two weeks my website has had a few changes to it, such as https and a theme upgrade, oh and a few speedups which really did need to happen. As mentioned in an earlier blog post, there’s still a couple of minor changes that need doing, but they’re not important at the moment.

My big project I want to get back to work on over this weekend because I’ve kind of left it behind for a while. Most times when I get home from work, I just sit on my backside watching TV with my laptop. So to fix this problem, I transferred all my projects to my laptop. Win win. I already had the router set to divert a test port to this laptop anyway, so with that change in the sources, last night, everything was back up and running, 100% perfect. The mobile app has just two things to finish off, and the media manager will get a rewrite.

I have noticed that the WebGl demos only work on full screen now and not embedded in a frame since the https thingy update. If I get round to it, then I’ll look into it. Web stuff really ain’t my thing, hardcore programming is.

If I get bored over the weekend I might also create a new home hosted website using GWT or CopperLicht even. We’ll see.

Early night for me tonight because it’s been three nights on the trot of hitting the weights bench. I think the peas on my arms are growing.

Until next time.

WLGfx

This website

I’ve still got a few formatting issues with this theme which will be ironed out over time.

I’ve noticed two so far. One with images not stretching to 100% of the posts width. And the other with using the <pre> tags and the line spacing.

Apart from that, I’ll be re-organising the menus so they look a lot better and categories stuff.

I’ve added a new java page about thread pooling which I want to work on a C++ version of it over the next day or two for my personal project.

Catch y’all soon.

Not much of an update but here goes

Got many plans, and little time to get everything done. The story of my life. he he

Anyways… My journey with the ffmpeg API has now taken another turn. Now I’m travelling the realm of using the AVIOContext. This is because I need to temporarily store a UDP transport stream locally when a pause of playback is required. Before the weekend I was non the wiser of how to do this, but after a good think about it, sorted.

All I need to do is to join the multicast stream manually, grab the packets, buffer them up and when ffmpeg, via the AVIOContext requests data, just send it. Simple. One problem I’ve yet to face is that after a pause, I want to be able to seek through the saved stream. I’ll come to that.

As for my own stuff. I’m kind of halfheartedly putting my feet up. I really need to put my feet up properly actually but I’ll take what I can get.

WebGL interactive

Nothing to show yet because it would be quite dull, but I’ve got mouse movement and click interaction working in the 3D scene. Basically, if the mouse clicks an object (when it’s not occluded) it will do stuff. And when the mouse hovers over an object. Old school really, but for WebGL, this can demonstrate a lot.

And at this time of night, I’m goosed.

Another little test on water in WebGL

I’d ‘scene’ it done lots of times and I already knew that CopperLicht could do it out of the box anyway so I thought a quick 5 minutes to get something done.

I wanted to have reflective water.

View the WebGL page

Most of the time when I get home from work I am ‘goosed’ and my brain just stops for the rest of the evening. I’m hoping to change that over the next coming months.

Now that I’ve faffed about with CopperCube, it’s time to use my old Irrlicht experience and put it to some WebGL stuff using the CopperLicht 3D engine. I’ve recently purchase a level editor that allows me to create Quake 3, Half Life, etc maps. All of which can be loaded into CopperLicht and Irrlicht. With the built in collision I plan on creating a ‘maybe’ funny scene using some dodgy A.I. running around a fully light-mapped scene. I’m already looking into it.

Over the next day or two, most likely two, then again maybe longer as the mother in law is down… I want to be a bit more creative with a level design and coding. The thorn in my side is Javascript. I’ve always avoided it because I’ve considered it useless, but lately after finding that the later browsers now compile it into byte code, it’s a little more impressive.

Still don’t like it.

Press SPACE to continue…

WebGL Demos

Okay, a new page WebGL Demos has been added. So far these have just been knocked up in CopperCube using the CopperLicht WebGL 3D engine. Very easy to use and for demonstration purposes, good for eye candy shows.

I’ve always tried hard to stay away from HTML, CSS and Javascript because I never saw the point when I’m a programmer that can do so much more than front end web stuff.

As time goes by I will be showcasing other engines such as LibGdx and Parallax3D.

So keep your eyes peeled…

Linux shell scripts

Another thing I’ve been playing about with for the last couple of weeks is automating stuff using shell scripting.

Wow! How much time can it save you by just writing a simple script.

There’s been loads of times when I wanted to backup my project. Not only can a small script do that but it can also rename and older backup file to something else as well. By just dropping a script into a directory and run it, I’m now capable of personal version control. Okay not quite the same thing, but I know what I mean.

I’m on the verge of now being able to run scripts to automatically update software on a remote machine too using ssl. So far I can package up various pieces of software (build them if needed too) and use the scp command to copy them to a remote machine. All I need to do next is to be able to run commands and scripts over ssl. Almost there.

This shell scripting is amazingly powerful.

Qt now works with the latest Android SDK/NDK

After a short time to install 5.9.2 of Qt and then without my fingers crossed even, I loaded up Qt and loaded one of the 3D Android compatible examples.

After the first build complaining about API level 1 I fixed that and ran it again. And voila! My phone ran it. All being very slow because it was that water demo one.

Woo hoo! Might be back to Qt for desktop and mobile app dev again.

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