LXR uboot/arch/arm/include/asm/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 */
 113