Re: [PATCH 1/3] usb: gadget: storage: Add fsg_get_toc helper

[Roger Quadros]

On 03/09/2011 05:10 PM, ext Alan Stern wrote:

> > +	case 2:
> > +		/* Raw TOC */
> > +		memset(buf, 0, 37);	/* Header + A0, A1&  A2 descriptors */
> > +		buf[1] = 37;		/* 4 + 3*11 */
>
> There's no reason to do it this way.  The compiler is a lot better than
> you are at addition.  Just put 4 + 3*11 in the assignment statement,
> and in the comment explain what the numbers mean.

OK.

> > +		buf[2] = 1;		/* First complete session */
> > +		buf[3] = 2;		/* Last complete session */
> > +
> > +		buf += 4;
> > +		/* A0 point */
> > +		buf[0] = 1;		/* Session number */
> > +		buf[1] = 0x16;		/* Data track, copying alowed */
> > +		/* 2 - Track number 0 ->  TOC */
> > +		buf[3] = 0xA0;		/* Point A0 */
> > +		/* 4, 5, 6 - Min, sec, frame is zero */
> > +		/* 7 - zero */
> > +		buf[8] = 1;		/* Pmin: 1st track number */
> > +		/* 9 - disc type 0: CD-ROM/DA with 1st track in mode 1 */
> > +		/* 10 - pframe 0 */
> > +
> > +		buf += 11;
> > +		/* A1 point*/
> > +		buf[0] = 1;		/* Session number */
> > +		buf[1] = 0x16;		/* Data track, copying alowed */
> > +		/* 2 - Track number 0 ->  TOC */
> > +		buf[3] = 0xA1;		/* Point A1 */
> > +		/* 4, 5, 6 - Min, sec, frame is zero */
> > +		/* 7, zero */
> > +		buf[8] = 1;		/* Pmin: last track number */
> > +		/* 9, 10 - pmin and pframe are 0 */
> > +
> > +		buf += 11;
> > +		/* A2 point*/
> > +		buf[0] = 1;		/* Session number */
> > +		buf[1] = 0x16;		/* Data track, copying alowed */
> > +		/* 2 - Track number 0 ->  TOC */
> > +		buf[3] = 0xA2;		/* Point A2 */
> > +		/* 4, 5, 6 - Min, sec, frame is zero */
> > +		/* 7, 8, 9, 10 - zero, Pmin, Psec, Pframe of Lead out */
> > +		store_cdrom_address(&buf[7], msf, curlun->num_sectors);
>
> These things could be put into a loop, instead of a separate function.

Yes loop is better than function for this case.

> > +		return 37;
>
> It might be a good idea to use a variable instead of having all these
> "37"s floating around.  It would make future updates more reliable.

OK.

--
regards,
-roger
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