binaryEncode/binaryDecode (was Re: Endian conversion problems)

[Dar Scott]

On Wednesday, August 6, 2003, at 03:37 PM, David Beck wrote:

> function ReadUInt16 filePath, count
>   if the platform is "Win32" then
>     read from file filePath for (count * 2)

Consider URL binfile:

>     put it into rawData
>     put "" into finalResult
>     put "" into curNum
>     repeat while rawData is not empty
>       put binaryDecode( "n", char 1 to 2 of rawData, curNum ) into  
> dummy
>       -- we need to give the number its sign ourselves, since
>       -- the 'n' flag always reads unsigned data on Windows.
>       if curNum < 0 then put 32768 + ( curNum + 32768 ) into curNum

Typo?  This can't be right.

>       put curNum & comma after finalResult

This is fast.  However, it converts numbers to strings.  You might want  
to consider using an array.

>       delete char 1 to 2 of rawData

This is slow for long strings.  There is probably a faster way using  
'char i to i+1 ...', but maybe not.

>     end repeat
>     delete the last char of finalResult
>   else
>     read from file filePath for count uint2
>     put it into finalResult

Did you edit out the non-Windows script?

>   end if
>
>   return finalResult
> end ReadUInt16
>
> This way you avoid doing a 1-byte file read for every number, which  
> would
> slow things down a lot.


> I also have cross platform functions to read/write
> big endian unsigned 2-byte ints and unsigned 4-byte ints. If anybody  
> would
> like them, drop me a note.

Cool.  That is the way to do it.  Will they still work when Windows is  
fixed?

Anybody willing to check sign/unsigned on linux?

Dar Scott


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