include/asm-arm/arch-sa1100/bitfield.h

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