Hi Mike
The tricky part is creating the 2-byte integers. Here is a useful function
to convert REBOL integers to 2-byte or 4-byte byte-reversed (Intel format)
binary values:
=====TO-BYTE FUNCTION======
to-byte: func [int [integer!] /long][
head reverse do join "#{" [(copy skip (to-string to-hex int) either
long [0][4]) "}"]
]
Example:
>> bin: to-byte 694
== #{B602}
Note: there is no checking for sign, so TO-BYTE will only work properly for
unsigned 2-byte up to 32767 and unsigned 4-byte up to 2147483647. It is
fairly easy to add code to allow REBOL negative integers to be
re-interpreted as the high-half unsigned's.
The field length is just one byte and can be generated as:
binary-byte: to-binary to-string to-char <integer between 0 and 255>
So, in outline, for each line to be written:
1) Convert the string content to binary
b-string: to-binary <data-string>
2) insert b-string binary-byte ; binary-byte as above
3) insert b-string to-byte <field number as integer between 0 and 32767>
4) write/binary/append <filename> b-string ; append the line to the file.
5) After all lines are written
write/binary/append <filename> #{FFFF}
HTH
-Larry
----- Original Message -----
From: Mike Duncan <[EMAIL PROTECTED]>
To: Rebol List <[EMAIL PROTECTED]>
Sent: Tuesday, November 14, 2000 1:39 PM
Subject: [REBOL] Unusual file format
> I need to create a file in Windows with the following format (not one I
> designed):
> Field number - 2 bytes in MS Lo-Hi order
> Field length - 1 byte
> String data - as many characters as specified in field length
>
> Using a hex editor the file would look like this:
> 01 00 05 41 42 43 44 45 02 00 10 41 42 43 44 45 ...ABCDEF...ABCDE
> 46 47 48 49 4A 4B 4C 4D 4E 4F 50 FF FF FGHIJKLMNOP..
>
> with field number 1, 5 characters "ABCDE"
> field number 2, 16 characters "ABCDEFGHIJKLMNOP"
> FF FF marks the end of the file.
>
> Any help would be appreciated. I'm new to Rebol and am having trouble with
> this one.
>
> TIA
>
> Mike
>
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