Convert binary data files between Big Endian and Little Endian with xxd

Here is a nifty command line trick you can use to convert binary data files between big endian and little endian format. So for example if you are using 4 byte / 32 bit words, byte swapping 0x1a2b3c4d to 0x4d3c2b1a.

"input.bin" is your input binary file.
"temp.txt" is an intermediate file that you can delete later.
"output.bin" is the output binary with all the 4 byte / 32 bit words endian swapped.

xxd -e -g4 input.bin temp.txt
xxd -r temp.txt output.bin

or if you want to skip using the temporary text file...

xxd -e -g4 input.bin | xxd -r > output.bin



The xxd tool is used to make a hexdump or convert a hexdump back into binary.

The xxd tool normally comes as part of the "vim" application, so if xxd isn't available on your system you might need to install vim. Additionally I don't think this will work with the busybox version of xxd found on embedded system because as far as I can see it doesn't currently support all the required command line options. The standard linux / BSD / unix version of xxd should be fine.

Note that this procedure does not convert executables between big endian and little endian, only binary data.

For example. Say I have a binary file "test.bin" as follows
 
00000000  41 42 43 44 45 46 47 48  49 4a 4b 4c 4d 4e 4f 50
00000010  51 52 53 54 55 56 57 58  59 5a 30 31 32 33 34 35
00000020  36 37 38 39 61 62 63 64  65 66 67 68 69 6a 6b 0a

First use "xxd -e -g4" to convert the binary file to a hexdump text file. The "-e" option says to use Little Endian output format. Use this option regardless of whether you're converting from Big to Little or Little to Big Endian. The "-g4" option specifies to use 4 bytes (32 bits) per word. You can use a different word size option with "-g".

xxd -e -g4 test.bin temp-hexdump.txt

The contents of temp-hexdump.txt are as follows

#cat temp-hexdump.txt
00000000: 44434241 48474645 4c4b4a49 504f4e4d  ABCDEFGHIJKLMNOP
00000010: 54535251 58575655 31305a59 35343332  QRSTUVWXYZ012345
00000020: 39383736 64636261 68676665 0a6b6a69  6789abcdefghijk.

Note that the 4 byte hex values in the middle are presented in little endian format (i.e. reversed) so for the first word instead of "41 42 43 44" we have "44 43 42 41".

Finally we use "xxd -r" convert this hexdump back to binary format. Note that xxd -r only looks at the numerical hex data so if you want to edit your text file, just edit the hex numbers not the strings at the right.

xxd -r temp-hexdump.txt test-new-endian.bin

The contents of the output file test-new-endian.bin are endian swapped from the original as follows

00000000  44 43 42 41 48 47 46 45  4c 4b 4a 49 50 4f 4e 4d
00000010  54 53 52 51 58 57 56 55  31 30 5a 59 35 34 33 32
00000020  39 38 37 36 64 63 62 61  68 67 66 65 0a 6b 6a 69


Finally note that if your input binary file size isn't a multiple of the chosen word size, such as 32 bits / 4 bytes, then the last couple of bytes in the file will be discarded. One thing you could do is manually edit the temporary hexdump text file in the middle of the process add some zeros to the hex data at the end to make your data have a whole number of words before executing "xxd -r".

I used this method as a basis to convert an "md" memory dump from the u-boot boot loader utility from one endian into another on my debian linux system. Obviously there are ways you can programmatically do this with python scripts and so forth but I always prefer using existing command line tools if possible.
 

Trance Techno - Sound of Goodbye by Armin van Buuren - About depression and suicide??

One of the many techno tunes that I love to listen to repeatedly is Armin van Buuren's catchy and hip "Sound of Goodbye".

This is a pretty good approximation of what I look like
at one of the many "raves", "techno soirees" and "trance shindigs"
I attend.

Here is a youtube link to the so called "Tribal Feel Edit" of the song which has a very "trancey" feel but there are other versions of "Sound of Goodbye" out there to suit everyone's taste in techno.

Her Majesty prefers the "Dubstep" style. 

In the clip the vocals are performed by the Dutch trance icon Elles de Graaf . You'll also see the quite fetching Ms de Graaf running half naked across an isolated green valley towards a lake where at the end of the clip she appears to drown herself.

You get to see her bottom just before she dies!!

The lyrics are as follows. I've numbered each of the lines. She doesn't actually sing the numbers they're just there for reference purposes later.

     1. Every face I see is cold as ice

     2. Everything I touch is pain

     3. Ever since I lost imagination

     4. Like a stream that flows into the sea

     5. I am lost for all eternity

     6. Ever since you took your love away from me

     (Repeat lines 7 & 8 till the end of the song......)

     7. Sometimes the sound of goodbye

     8. Is louder than any drumbeat

The first two lines of the lyrics tell us that this poor damsel can't stand human contact any more and that everything is giving her pain. I think this describes the experience of extreme unipolar clinical depression poetically and precisely. The social withdrawal, the feeling that no one loves or cares for you, and that the only emotions you can experience are negative ones.

The third line talks about "lost imagination" being the trigger for her misery. Could it be some important relationship that she thought she had with someone that turned out to be imaginary, like a love that ended up not being reciprocated, or a friendship that wasn't as strong as she thought. One other possibility is that she has lost her faith in God. The God that she once thought was real but was actually only "imagination".

Depression can often be triggered by some kind of heartbreak or painful emotional event. I think this is what has sent the lovely Elles into her spiral of unhappiness.

I'll be your friend Elles! Come and stay at my house!

My wife won't mind. She can take the kids and go and live 

with her parents for a few weeks.

Lines 4 and 5 talk about how she feels like water from a stream that gets lost in the sea. That is, she thinks that her life doesn't matter and in the grand scheme of things she is insignificant and means nothing. Again this is the typical thought pattern of someone who is severely depressed.

Line 6 talks about the trigger for her illness again. "Ever since you took your love away from me". Again, I think this implies a failed relationship or a lost faith. The experience of rejection by person or God is, I believe, one of the worst things that a sensitive maiden such as Juffrouw de Graaf can endure and is something that could definitely be the spark for the psychological inferno of major depression.

"Juffrouw" is Dutch for "Missus". Google told me.

Now on to the "chorus". Lines 7 and 8 say that the sound of goodbye, which I think clearly refers to the act of killing yourself, is "Louder than any drumbeat".

The meaning of "drumbeat" here is pretty ambiguous. My first guess is that it might be a metaphor for her heartbeat which is in turn a symbol for her being alive. If this is what it's saying then the chorus means that she thinks that her suicide is more significant and matters more (louder) than her life.

The other alternative revolves around the idea that beating drums were used as a form of communication in some ancient cultures. Is she saying that she's tried to communicate with others about her pain and distress but that no one has listened, but that by drowning herself she'll finally get others to pay attention?

Ancient cultures also used smoke signals to communicate but

everyone thought "drumbeat" sounded cooler.

After all that detailed analysis I think it's quite reasonable and safe to assume that this song is indeed about the thoughts and emotions of a depressed woman who is going to die by her own hand. 

At this point in the post I think I'm supposed to appeal to anyone with depression or thoughts about suicide to contact a doctor or psychiatrist or something. Especially if you're an attractive techno princess with the voice of an angel.

 Just take some Prozac and get some shock treatment and

you'll be fine.