Re: [Audacity-nyquist] read-int issue

[Dominic M. <do...@au...>]

Evan,

Nyquist's version of xlisp always reads big-endian numbers, which is  
the opposite of what you'd normally want on an Intel (i.e. Windows or  
typical Linux) machine.  Pass a negative number to read a little- 
endian integer:

> (setq tempWidth (read-int filePointer -2))
> (setq tempHeight (read-int filePointer -2))

- Dominic


On Jul 1, 2005, at 2:05 AM, Evan Merz wrote:
> Thanks for all the suggestions, they were all good
> ideas, but perhaps I'm not getting the issue right
> after all....  as none of your suggestions seemed to
> produce the intended results.
>
> I'm reading tga images, a format that is ridiculously
> simple, and for which I have working C code. When I
> read the height/width of certain images, however, I
> get bizarre results from nyquist, that I don't get in
> C.
>
> here's my C code:
> fread(&header->width, 2, 1, inputFile);
> fread(&header->height, 2, 1, inputFile);
>
> here's my nyquist code:
> (setq tempWidth (read-int filePointer 2))
> (setq tempHeight (read-int filePointer 2))
>
> In C everything works great, but in nyquist, I get
> crazy numbers.
>
> for a while I was just dividing by 256 ( I don't
> remember why) and that seemed to work on small images
> - 50x1 for instance.
>
> But from images of diverse sizes, I get strange
> numbers.  Since some were large and negative, I was
> assuming it was a sign thing, but after playing with
> your suggestions, I can see that that doesn't appear
> to be the case.
>
> I imagine that there's something that I'm missing in
> the nyquist specification which points out a subtle
> difference in how it stores numbers versus the way gnu
> c does it... anyone have any ideas?
>
> Oh, I also read something about turning off boundary
> alignment in a C compiler, because that might cause a
> misinterpretation of the bytes... might something like
> that be occurring here?
>
> thanks again, for any ideas,
>
> Evan Merz
>
>
>
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