bitfields

bitfield.h

#ifndef I__BITFIELD_H__
	#define I__BITFIELD_H__

/* Bitfield Macros
 *
 * A bitfield is any range of bits in a word. A bitfield definition
 * needs to specify the SIZE and SHIFT in the following format:
 * 	#define BITFIELD_NAME SIZE:SHIFT
 * Examples (X is don't care, F is the field):
 * 	Register: XXXXXFFX = Bitfield 2:1
 * 	Register: XXXXXFFF = Bitfield 3:0
 * 	Register: XXXXFXXX = Bitfield 1:3
 */
#define _BFSIZE(bf)	(1 ? bf)
#define _BFSHIFT(bf)	(0 ? bf)

#ifndef BF
#define BF(bfdef, bfval)			\
	(((bfval) & ((1 << _BFSIZE(bfdef)) - 1)) << _BFSHIFT(bfdef))
#endif

#ifndef INSERTBF
#define INSERTBF(bfdef, bfval, targetval)	\
	do { \
		(targetval) = ((targetval) \
			& ~(((1 << _BFSIZE(bfdef)) - 1) << _BFSHIFT(bfdef))) \
			| BF(bfdef, bfval); \
	} while(0)
#endif

#ifndef GETBF
#define GETBF(bfdef, val)			\
	((val >> _BFSHIFT(bfdef)) & ((1 << _BFSIZE(bfdef)) - 1))
#endif

#endif /* I__BITFIELD_H__ */