Add GET_BIT() and GET_BITS() macros to bit.h

[singalsu]

These macros are useful for decoding bit fields.

Signed-off-by: Seppo Ingalsuo seppo.ingalsuo@linux.intel.com

[lgirdwood]

@singalsu can you check and see if these are the same naming and usages as Zephyr versions. We should align.

[singalsu]

There's in Zephyr e.g. drivers/neural_net/intel_gna.h one with different way than mine. This shifts left and right other bits out of uint32 except requested one. Mine ANDs with bit mask and shift right the result, and works with other world lengths too. The macro params order is different.

#define GNA_GET_BITS(val, b_hi, b_lo)	((((uint32_t)(val)) << (31 - (b_hi))) >> \
		(31 - (b_hi) + (b_lo)))

I could not spot anything similar from https://github.com/zephyrproject-rtos/zephyr with quick grep for BIT and GET.

Edit: one more from drivers/ethernet/eth_smsc911x_priv.h with different way and different macro parameters. This might fail with 64 bit.

#define GET_BITFIELD(val, lsb, msb) \
	(((val) >> (lsb)) & ((1 << ((msb) - (lsb) + 1)) - 1))

[paulstelian97]

Won't approve until I see the intended use case.

[singalsu]

@paulstelian97 The macros are used in this another PR file https://github.com/thesofproject/sof/blob/8d68ef2832b4fcdfabaccce00f95952a09a6b3a5/src/drivers/intel/dmic/dmic_nhlt.c . It was a proposal by Liam to make a separate PR for this.

Edit: Sorry, not that file but the header it uses https://github.com/thesofproject/sof/blob/8d68ef2832b4fcdfabaccce00f95952a09a6b3a5/src/include/sof/drivers/dmic.h . See e.g. line 161 ->

[lgirdwood]

@nashif @andyross we would like to add some macros for getting registers bits, but would obviously like to align with Zephyr. Is there anything similar in Zephyr today and if not, would this be something that would be added later ?

[paulstelian97]

I guess they look good now. An extra commit to use MASK in the pre-existing SET_BITS wouldn't be bad but I won't require it.