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1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  *	FILE    	bitfield.h
4  *
5  *	Version 	1.1
6  *	Author  	Copyright (c) Marc A. Viredaz, 1998
7  *	        	DEC Western Research Laboratory, Palo Alto, CA
8  *	Date    	April 1998 (April 1997)
9  *	System  	Advanced RISC Machine (ARM)
10  *	Language	C or ARM Assembly
11  *	Purpose 	Definition of macros to operate on bit fields.
12  */
13 
14 
15 
16 #ifndef __BITFIELD_H
17 #define __BITFIELD_H
18 
19 #ifndef __ASSEMBLY__
20 #define UData(Data)	((unsigned long) (Data))
21 #else
22 #define UData(Data)	(Data)
23 #endif
24 
25 
26 /*
27  * MACRO: Fld
28  *
29  * Purpose
30  *    The macro "Fld" encodes a bit field, given its size and its shift value
31  *    with respect to bit 0.
32  *
33  * Note
34  *    A more intuitive way to encode bit fields would have been to use their
35  *    mask. However, extracting size and shift value information from a bit
36  *    field's mask is cumbersome and might break the assembler (255-character
37  *    line-size limit).
38  *
39  * Input
40  *    Size      	Size of the bit field, in number of bits.
41  *    Shft      	Shift value of the bit field with respect to bit 0.
42  *
43  * Output
44  *    Fld       	Encoded bit field.
45  */
46 
47 #define Fld(Size, Shft)	(((Size) << 16) + (Shft))
48 
49 
50 /*
51  * MACROS: FSize, FShft, FMsk, FAlnMsk, F1stBit
52  *
53  * Purpose
54  *    The macros "FSize", "FShft", "FMsk", "FAlnMsk", and "F1stBit" return
55  *    the size, shift value, mask, aligned mask, and first bit of a
56  *    bit field.
57  *
58  * Input
59  *    Field     	Encoded bit field (using the macro "Fld").
60  *
61  * Output
62  *    FSize     	Size of the bit field, in number of bits.
63  *    FShft     	Shift value of the bit field with respect to bit 0.
64  *    FMsk      	Mask for the bit field.
65  *    FAlnMsk   	Mask for the bit field, aligned on bit 0.
66  *    F1stBit   	First bit of the bit field.
67  */
68 
69 #define FSize(Field)	((Field) >> 16)
70 #define FShft(Field)	((Field) & 0x0000FFFF)
71 #define FMsk(Field)	(((UData (1) << FSize (Field)) - 1) << FShft (Field))
72 #define FAlnMsk(Field)	((UData (1) << FSize (Field)) - 1)
73 #define F1stBit(Field)	(UData (1) << FShft (Field))
74 
75 
76 /*
77  * MACRO: FInsrt
78  *
79  * Purpose
80  *    The macro "FInsrt" inserts a value into a bit field by shifting the
81  *    former appropriately.
82  *
83  * Input
84  *    Value     	Bit-field value.
85  *    Field     	Encoded bit field (using the macro "Fld").
86  *
87  * Output
88  *    FInsrt    	Bit-field value positioned appropriately.
89  */
90 
91 #define FInsrt(Value, Field) \
92                 	(UData (Value) << FShft (Field))
93 
94 
95 /*
96  * MACRO: FExtr
97  *
98  * Purpose
99  *    The macro "FExtr" extracts the value of a bit field by masking and
100  *    shifting it appropriately.
101  *
102  * Input
103  *    Data      	Data containing the bit-field to be extracted.
104  *    Field     	Encoded bit field (using the macro "Fld").
105  *
106  * Output
107  *    FExtr     	Bit-field value.
108  */
109 
110 #define FExtr(Data, Field) \
111                 	((UData (Data) >> FShft (Field)) & FAlnMsk (Field))
112 
113 
114 #endif /* __BITFIELD_H */
115