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Posted by Jerry Stuckle on 10/17/07 20:48
Bint wrote:
> Yeah, I guess I'm trying to do something low-level with this high-level
> lanugage. I'm new to PHP so I'm trying to figure out how these fancy
> keyword-based arrays work with old-school byte arrays.
>
> I'm sending images wirelessly to a php script. The image, originally a grid
> of pixels, each 16-bits deep, is run-length-encoded into a smaller C array
> of unsigned shorts (16 bit words). That C array is base64 encoded into an
> ASCII string so that I can send it via HTTP POST command to a PHP script.
>
> The PHP script sees my base64 encoded array as a variable, which I can
> easily base64 decode into a php "array". But it is proving trickier to
> access my pixel values, because now the array is not a C array, but a PHP
> one. If I look at the value of array[0], then I don't get the number that
> was in array[0] before I sent it.
>
> I can work around it, by accessing each byte of the PHP array:
>
> $myoriginalarray[0] = ord($phparray[0]) + ord($phparray[1]) << 8;
>
> But that is complicated and I just thought there might be some simpler way
> of telling PHP "hey, I have an array of unsigned shorts here".
> Maybe not.
>
> B
>
>
>
>
>
>
> "Jerry Stuckle" <jstucklex@attglobal.net> wrote in message
> news:D_SdneeS0bxw8YvanZ2dnUVZ_qHinZ2d@comcast.com...
>> Bint wrote:
>>> I have an array whose elements I'm accessing, like array[0], array[1],
>>> etc.
>>> However, the data is meant to be 16-bit words, not bytes. I'm getting
>>> byte values right now. Is there
>>> any way I can tell php that an array is composed of words and not bytes?
>>>
>>> Thanks
>>> B
>>>
>>>
>>>
>> Not really. PHP is not meant for low-level bit manipulation. And you
>> can't really control the size of the word - it can differ between 32 and
>> 64 bit architectures, for instance.
>>
>> What are you string in those words, anyway?
>>
>> --
>> ==================
>> Remove the "x" from my email address
>> Jerry Stuckle
>> JDS Computer Training Corp.
>> jstucklex@attglobal.net
>> ==================
>>
>
>
>
Nope, not really. But I think I'd do that processing in C anyway.
Either call it as an external module or write an extension to PHP for it.
--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
==================
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