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Once apon a time along time ago I was introduced to a technique called hi-nibble/lo-nibble. Back then I was a pascal newbie trying hard to pass GCSEs.
The principle was simple useing (128 I think) and some maths function one could take the first two parts of a string and store them in one byte. High and low!!
The problem is now that I have a usefull function for this fella I can't remember it.
If anyone has any idea what I am on about please help.
I believe it was called Endian Encoding. I've seen it used in
applications that require the storage of relative large amounts of
character data in a smaller space. The one I remember most was
a program called NUTS that was used to analyze Nuclear
Magnetic Resonance images.
Essentially, the first 4 nibbles of the byte refer to the first of a
hex value, the second refers to the second byte of the hex
value. It's a two for one saving.
The decoding function went something like this:
(Character and 240)*256 + (character and 15) = Decimal Value
Not too much application, tho.....
In general, one cannot store the information about two 8-bit bytes in one 8-bit byte.
Due to the nature of certain files, there are compression schemes which will encode a file so that it can be stored in less than half the space required for the original file. WinZip will do this.
I knew it!!!!
Thankyou. If you could put up with me a little longer how can I apply that formula (is that for in or out) it's been a while since I had to rearrange an equation.
Thanks again.
ummmm...I think I mis-spoke.
The process I was thinking of is a way of encoding numbers in a
text file, at least the endian process used by Nuts.
is an example of the ecoding. Each character represents a valueQuote:
K° RÌ5ŠRKXƒÌù&ÝJâ»1Ì LŽK
that would take 4 or 5 characters to represent in text format.
http://www.acornnmr.com/NutsHelp/cdff.html#3
is the page describing the file that uses it. the quote above
comes after the verbiage....
Sorry.:rolleyes:
Guv was right....as usual.
Ok, thanx anyway.
I guess me old memory didn't do the lesson justice.
ta' for your time.
[edit]
That was one very old and long time ago lesson
[/edit]
By gov:
It seems that many people think it is possible to do so, and try to make programs making this possible.Quote:
In general, one cannot store the information about two 8-bit bytes in one 8-bit byte.
Whatever happens, you can't!! There is no way you can make a 'zipping program' that will always compress files. There is just no possible way of making 2^n combinations (using n BITs), and converting them to 2 ^ n-1 combinations using one method, such that all of the 2^n can be compressed. The only thing you can do is rearrange/alter the already used n BITs.
Also, there is a simple way of writing numbers to files so that the file size is smaller.
All you have to do is split the number into 2-digit blocks, the save chr$(2-digit + 65). This is so that the 'nasty' low down CHR$() things, such as new-line, clear screen etc. are not included.
Finally, for ultimate minimization of numbers, convert the whole thing into a binary strain, with each block of 4 (3 only gives numbers 0 - 7) standing for each digit. This is kind of like what someone else was saying. (NOte, this doen't always work, sometimes you get bigger files)
By gov:
there is a simple way of writing numbers to files so that the file size is smaller.Quote:
In general, one cannot store the information about two 8-bit bytes in one 8-bit byte.
save the file as binary instead of text :cool:.
:rolleyes: I feel a little foolish.
Twas searching 4 a way to make my files hard to read for storing midly sensitive data in.
:(