Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit bf33eb4b authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
Browse files

staging: comedi: introduce some sample size manipulation functions 



Introduce a few static inline helper functions:

`comedi_bytes_per_sample(s)` is the same as the existing
`bytes_per_sample(s)` and determines the size of a comedi sample in
bytes.  (`bytes_per_sample(s)` will be removed.)

`comedi_sample_shift(s)` determines the log2 of the comedi sample size,
so it can be used in bit-shift operations to multiply or divide by the
sample size.

`comedi_bytes_to_samples(s, nbytes)` converts a number of bytes to a
number of samples (rounding down).

`comedi_samples_to_bytes(s, nsamples)` converts a number of samples to a
number of bytes.

Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Reviewed-by: default avatarH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7885b070

drivers/staging/comedi/comedidev.h

+59 −4
Original line number Diff line number Diff line
@@ -413,12 +413,67 @@ static inline unsigned int comedi_offset_munge(struct comedi_subdevice *s, 
	return val ^ s->maxdata ^ (s->maxdata >> 1);

}



static inline unsigned int bytes_per_sample(const struct comedi_subdevice *subd)

/**

 * comedi_bytes_per_sample - determine subdevice sample size

 * @s:		comedi_subdevice struct

 *

 * The sample size will be 4 (sizeof int) or 2 (sizeof short) depending on

 * whether the SDF_LSAMPL subdevice flag is set or not.

 *

 * Returns the subdevice sample size.

 */

static inline unsigned int comedi_bytes_per_sample(struct comedi_subdevice *s)

{

	if (subd->subdev_flags & SDF_LSAMPL)

		return sizeof(unsigned int);

	return s->subdev_flags & SDF_LSAMPL ? sizeof(int) : sizeof(short);

}



	return sizeof(short);

/* to be removed */

static inline unsigned int bytes_per_sample(struct comedi_subdevice *s)

{

	return comedi_bytes_per_sample(s);

}



/**

 * comedi_sample_shift - determine log2 of subdevice sample size

 * @s:		comedi_subdevice struct

 *

 * The sample size will be 4 (sizeof int) or 2 (sizeof short) depending on

 * whether the SDF_LSAMPL subdevice flag is set or not.  The log2 of the

 * sample size will be 2 or 1 and can be used as the right operand of a

 * bit-shift operator to multiply or divide something by the sample size.

 *

 * Returns log2 of the subdevice sample size.

 */

static inline unsigned int comedi_sample_shift(struct comedi_subdevice *s)

{

	return s->subdev_flags & SDF_LSAMPL ? 2 : 1;

}



/**

 * comedi_bytes_to_samples - converts a number of bytes to a number of samples

 * @s:		comedi_subdevice struct

 * @nbytes:	number of bytes

 *

 * Returns the number of bytes divided by the subdevice sample size.

 */

static inline unsigned int comedi_bytes_to_samples(struct comedi_subdevice *s,

						   unsigned int nbytes)

{

	return nbytes >> comedi_sample_shift(s);

}



/**

 * comedi_samples_to_bytes - converts a number of samples to a number of bytes

 * @s:		comedi_subdevice struct

 * @nsamples:	number of samples

 *

 * Returns the number of samples multiplied by the subdevice sample size.

 * Does not check for arithmetic overflow.

 */

static inline unsigned int comedi_samples_to_bytes(struct comedi_subdevice *s,

						   unsigned int nsamples)

{

	return nsamples << comedi_sample_shift(s);

}



/*