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/arch/arm/mach-pxa/include/mach/bitfield.h

https://github.com/AICP/kernel_asus_grouper
C Header | 113 lines | 18 code | 18 blank | 77 comment | 0 complexity | 9b99dab391cc8d2de8bc6de42ad5e705 MD5 | raw file
  1/*
  2 *	FILE    	bitfield.h
  3 *
  4 *	Version 	1.1
  5 *	Author  	Copyright (c) Marc A. Viredaz, 1998
  6 *	        	DEC Western Research Laboratory, Palo Alto, CA
  7 *	Date    	April 1998 (April 1997)
  8 *	System  	Advanced RISC Machine (ARM)
  9 *	Language	C or ARM Assembly
 10 *	Purpose 	Definition of macros to operate on bit fields.
 11 */
 12
 13
 14
 15#ifndef __BITFIELD_H
 16#define __BITFIELD_H
 17
 18#ifndef __ASSEMBLY__
 19#define UData(Data)	((unsigned long) (Data))
 20#else
 21#define UData(Data)	(Data)
 22#endif
 23
 24
 25/*
 26 * MACRO: Fld
 27 *
 28 * Purpose
 29 *    The macro "Fld" encodes a bit field, given its size and its shift value
 30 *    with respect to bit 0.
 31 *
 32 * Note
 33 *    A more intuitive way to encode bit fields would have been to use their
 34 *    mask. However, extracting size and shift value information from a bit
 35 *    field's mask is cumbersome and might break the assembler (255-character
 36 *    line-size limit).
 37 *
 38 * Input
 39 *    Size      	Size of the bit field, in number of bits.
 40 *    Shft      	Shift value of the bit field with respect to bit 0.
 41 *
 42 * Output
 43 *    Fld       	Encoded bit field.
 44 */
 45
 46#define Fld(Size, Shft)	(((Size) << 16) + (Shft))
 47
 48
 49/*
 50 * MACROS: FSize, FShft, FMsk, FAlnMsk, F1stBit
 51 *
 52 * Purpose
 53 *    The macros "FSize", "FShft", "FMsk", "FAlnMsk", and "F1stBit" return
 54 *    the size, shift value, mask, aligned mask, and first bit of a
 55 *    bit field.
 56 *
 57 * Input
 58 *    Field     	Encoded bit field (using the macro "Fld").
 59 *
 60 * Output
 61 *    FSize     	Size of the bit field, in number of bits.
 62 *    FShft     	Shift value of the bit field with respect to bit 0.
 63 *    FMsk      	Mask for the bit field.
 64 *    FAlnMsk   	Mask for the bit field, aligned on bit 0.
 65 *    F1stBit   	First bit of the bit field.
 66 */
 67
 68#define FSize(Field)	((Field) >> 16)
 69#define FShft(Field)	((Field) & 0x0000FFFF)
 70#define FMsk(Field)	(((UData (1) << FSize (Field)) - 1) << FShft (Field))
 71#define FAlnMsk(Field)	((UData (1) << FSize (Field)) - 1)
 72#define F1stBit(Field)	(UData (1) << FShft (Field))
 73
 74
 75/*
 76 * MACRO: FInsrt
 77 *
 78 * Purpose
 79 *    The macro "FInsrt" inserts a value into a bit field by shifting the
 80 *    former appropriately.
 81 *
 82 * Input
 83 *    Value     	Bit-field value.
 84 *    Field     	Encoded bit field (using the macro "Fld").
 85 *
 86 * Output
 87 *    FInsrt    	Bit-field value positioned appropriately.
 88 */
 89
 90#define FInsrt(Value, Field) \
 91                	(UData (Value) << FShft (Field))
 92
 93
 94/*
 95 * MACRO: FExtr
 96 *
 97 * Purpose
 98 *    The macro "FExtr" extracts the value of a bit field by masking and
 99 *    shifting it appropriately.
100 *
101 * Input
102 *    Data      	Data containing the bit-field to be extracted.
103 *    Field     	Encoded bit field (using the macro "Fld").
104 *
105 * Output
106 *    FExtr     	Bit-field value.
107 */
108
109#define FExtr(Data, Field) \
110                	((UData (Data) >> FShft (Field)) & FAlnMsk (Field))
111
112
113#endif /* __BITFIELD_H */