Re: [Audacity-nyquist] read-int issue

[Sami J. <sam...@gm...>]

Ah, I went a bit off because I thought you were reading audio data. Well.

> here's my C code:
> fread(&header->width, 2, 1, inputFile);
> fread(&header->height, 2, 1, inputFile);
>=20
> here's my nyquist code:
> (setq tempWidth (read-int filePointer 2))
> (setq tempHeight (read-int filePointer 2))
>=20
> In C everything works great, but in nyquist, I get
> crazy numbers.

Does the Lisp example above read 2 INTEGERS instead of two bytes? I
don't know the syntax nor the targa file format, but that would
explain the crazy numbers.
=20
> 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?

I think (I'm not C expert either... so why am I writing here!!?) that
relates to way structures are stored. For example in Delphi 5 (Object
Pascal) there is a compiler directive "Aligned record fields" and that
is explained in the help:
"Aligns elements in structures to 32-bit boundaries."
When reading/handling structures, this is a very important issue, and
good to keep in mind generally when reading data from files not
written by yourself. Remeber also related keyword: padding.

--=20
Sami "Some-E" Jumppanen
sam...@gm...
http://netti.nic.fi/~some-e/