Re: [linux-audio-dev] CDDA interface - How to convert to float? Any library?

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Subject: Re: [linux-audio-dev] CDDA interface - How to convert to float? Any library?
From: Martin Wolters (martinwolters_AT_yahoo.com)
Date: Sun Aug 11 2002 - 04:32:55 EEST

Oh well. So now the "official" code looks like this:

#include <endian.h>

unsigned char * in; //point to buffer returned by cd_read_audio

#if __BYTE_ORDER == __LITTLE_ENDIAN
        short input = (short)(in[0]|(in[1] << 8));
#else
        short input = (short)(in[1]|(in[0] << 8));
        // ?? didn't test this configuration.
        // Don't know if byte order of CD data is changed
        // on different patforms.
#endif

I guess it only worked "by chance" before.

-M

On Saturday 10 August 2002 17:08, Mark Rages wrote:
> On Sun, Aug 11, 2002 at 09:38:42AM +1000, Erik de Castro Lopo wrote:
> > On Sat, 10 Aug 2002 18:32:36 -0500
> >
> > Mark Rages <markrages_AT_mlug.missouri.edu> wrote:
> > > Ahh, I forgot CDDA is signed.
> > >
> > > Yes, I meant the u16 in the general sense that you picked up on.
> > >
> > > Well, you can try a byte-swap like this:
> > >
> > > #include <string.h> // for swab()
> > > #include <asm/byteorder.h> // for __LITTLE_ENDIAN macro
> >
> > In my last replay I suggested that you not use headers like <linux/*.h>
> > and in this one, I'm goint to suggest that you not use <asm/*.h> headers.
> >
> > You will also find __LITTLE_ENDIAN (and __BIG_ENDIAN) in <endian.h> which
> > is designed to be used in user space programs.
> >
> > Erik
>
> Not only that, but I screwed up the test for endianness.
>
> Instead of
>
> #ifdef __LITTLE_ENDIAN
>
> it should be
>
> #if __BYTE_ORDER == __LITTLE_ENDIAN
>
> Regards,
> Mark

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