/* *	FILE		bitfield.h * *	Version		1.1 *	Author		Copyright (c) Marc A. Viredaz, 1998 *			DEC Western Research Laboratory, Palo Alto, CA *	Date		April 1998 (April 1997) *	System		Advanced RISC Machine (ARM) *	Language	C or ARM Assembly *	Purpose		Definition of macros to operate on bit fields. */#ifndef __BITFIELD_H#define __BITFIELD_H#ifndef __ASSEMBLY__#define UData(Data)	((unsigned long) (Data))#else#define UData(Data)	(Data)#endif/* * MACRO: Fld * * Purpose *    The macro "Fld" encodes a bit field, given its size and its shift value *    with respect to bit 0. * * Note *    A more intuitive way to encode bit fields would have been to use their *    mask. However, extracting size and shift value information from a bit *    field's mask is cumbersome and might break the assembler (255-character *    line-size limit). * * Input *    Size		Size of the bit field, in number of bits. *    Shft		Shift value of the bit field with respect to bit 0. * * Output *    Fld		Encoded bit field. */#define Fld(Size, Shft)	(((Size) << 16) + (Shft))/* * MACROS: FSize, FShft, FMsk, FAlnMsk, F1stBit * * Purpose *    The macros "FSize", "FShft", "FMsk", "FAlnMsk", and "F1stBit" return *    the size, shift value, mask, aligned mask, and first bit of a *    bit field. * * Input *    Field		Encoded bit field (using the macro "Fld"). * * Output *    FSize		Size of the bit field, in number of bits. *    FShft		Shift value of the bit field with respect to bit 0. *    FMsk		Mask for the bit field. *    FAlnMsk		Mask for the bit field, aligned on bit 0. *    F1stBit		First bit of the bit field. */#define FSize(Field)	((Field) >> 16)#define FShft(Field)	((Field) & 0x0000FFFF)#define FMsk(Field)	(((UData (1) << FSize (Field)) - 1) << FShft (Field))#define FAlnMsk(Field)	((UData (1) << FSize (Field)) - 1)#define F1stBit(Field)	(UData (1) << FShft (Field))/* * MACRO: FInsrt * * Purpose *    The macro "FInsrt" inserts a value into a bit field by shifting the *    former appropriately. * * Input *    Value		Bit-field value. *    Field		Encoded bit field (using the macro "Fld"). * * Output *    FInsrt		Bit-field value positioned appropriately. */#define FInsrt(Value, Field) \			(UData (Value) << FShft (Field))/* * MACRO: FExtr * * Purpose *    The macro "FExtr" extracts the value of a bit field by masking and *    shifting it appropriately. * * Input *    Data		Data containing the bit-field to be extracted. *    Field		Encoded bit field (using the macro "Fld"). * * Output *    FExtr		Bit-field value. */#define FExtr(Data, Field) \			((UData (Data) >> FShft (Field)) & FAlnMsk (Field))#endif /* __BITFIELD_H */