1*819833afSPeter Tyser /* 2*819833afSPeter Tyser * FILE bitfield.h 3*819833afSPeter Tyser * 4*819833afSPeter Tyser * Version 1.1 5*819833afSPeter Tyser * Author Copyright (c) Marc A. Viredaz, 1998 6*819833afSPeter Tyser * DEC Western Research Laboratory, Palo Alto, CA 7*819833afSPeter Tyser * Date April 1998 (April 1997) 8*819833afSPeter Tyser * System Advanced RISC Machine (ARM) 9*819833afSPeter Tyser * Language C or ARM Assembly 10*819833afSPeter Tyser * Purpose Definition of macros to operate on bit fields. 11*819833afSPeter Tyser */ 12*819833afSPeter Tyser 13*819833afSPeter Tyser 14*819833afSPeter Tyser #ifndef __BITFIELD_H 15*819833afSPeter Tyser #define __BITFIELD_H 16*819833afSPeter Tyser 17*819833afSPeter Tyser #ifndef __ASSEMBLY__ 18*819833afSPeter Tyser #define UData(Data) ((unsigned long) (Data)) 19*819833afSPeter Tyser #else 20*819833afSPeter Tyser #define UData(Data) (Data) 21*819833afSPeter Tyser #endif 22*819833afSPeter Tyser 23*819833afSPeter Tyser 24*819833afSPeter Tyser /* 25*819833afSPeter Tyser * MACRO: Fld 26*819833afSPeter Tyser * 27*819833afSPeter Tyser * Purpose 28*819833afSPeter Tyser * The macro "Fld" encodes a bit field, given its size and its shift value 29*819833afSPeter Tyser * with respect to bit 0. 30*819833afSPeter Tyser * 31*819833afSPeter Tyser * Note 32*819833afSPeter Tyser * A more intuitive way to encode bit fields would have been to use their 33*819833afSPeter Tyser * mask. However, extracting size and shift value information from a bit 34*819833afSPeter Tyser * field's mask is cumbersome and might break the assembler (255-character 35*819833afSPeter Tyser * line-size limit). 36*819833afSPeter Tyser * 37*819833afSPeter Tyser * Input 38*819833afSPeter Tyser * Size Size of the bit field, in number of bits. 39*819833afSPeter Tyser * Shft Shift value of the bit field with respect to bit 0. 40*819833afSPeter Tyser * 41*819833afSPeter Tyser * Output 42*819833afSPeter Tyser * Fld Encoded bit field. 43*819833afSPeter Tyser */ 44*819833afSPeter Tyser 45*819833afSPeter Tyser #define Fld(Size, Shft) (((Size) << 16) + (Shft)) 46*819833afSPeter Tyser 47*819833afSPeter Tyser 48*819833afSPeter Tyser /* 49*819833afSPeter Tyser * MACROS: FSize, FShft, FMsk, FAlnMsk, F1stBit 50*819833afSPeter Tyser * 51*819833afSPeter Tyser * Purpose 52*819833afSPeter Tyser * The macros "FSize", "FShft", "FMsk", "FAlnMsk", and "F1stBit" return 53*819833afSPeter Tyser * the size, shift value, mask, aligned mask, and first bit of a 54*819833afSPeter Tyser * bit field. 55*819833afSPeter Tyser * 56*819833afSPeter Tyser * Input 57*819833afSPeter Tyser * Field Encoded bit field (using the macro "Fld"). 58*819833afSPeter Tyser * 59*819833afSPeter Tyser * Output 60*819833afSPeter Tyser * FSize Size of the bit field, in number of bits. 61*819833afSPeter Tyser * FShft Shift value of the bit field with respect to bit 0. 62*819833afSPeter Tyser * FMsk Mask for the bit field. 63*819833afSPeter Tyser * FAlnMsk Mask for the bit field, aligned on bit 0. 64*819833afSPeter Tyser * F1stBit First bit of the bit field. 65*819833afSPeter Tyser */ 66*819833afSPeter Tyser 67*819833afSPeter Tyser #define FSize(Field) ((Field) >> 16) 68*819833afSPeter Tyser #define FShft(Field) ((Field) & 0x0000FFFF) 69*819833afSPeter Tyser #define FMsk(Field) (((UData (1) << FSize (Field)) - 1) << FShft (Field)) 70*819833afSPeter Tyser #define FAlnMsk(Field) ((UData (1) << FSize (Field)) - 1) 71*819833afSPeter Tyser #define F1stBit(Field) (UData (1) << FShft (Field)) 72*819833afSPeter Tyser 73*819833afSPeter Tyser 74*819833afSPeter Tyser /* 75*819833afSPeter Tyser * MACRO: FInsrt 76*819833afSPeter Tyser * 77*819833afSPeter Tyser * Purpose 78*819833afSPeter Tyser * The macro "FInsrt" inserts a value into a bit field by shifting the 79*819833afSPeter Tyser * former appropriately. 80*819833afSPeter Tyser * 81*819833afSPeter Tyser * Input 82*819833afSPeter Tyser * Value Bit-field value. 83*819833afSPeter Tyser * Field Encoded bit field (using the macro "Fld"). 84*819833afSPeter Tyser * 85*819833afSPeter Tyser * Output 86*819833afSPeter Tyser * FInsrt Bit-field value positioned appropriately. 87*819833afSPeter Tyser */ 88*819833afSPeter Tyser 89*819833afSPeter Tyser #define FInsrt(Value, Field) \ 90*819833afSPeter Tyser (UData (Value) << FShft (Field)) 91*819833afSPeter Tyser 92*819833afSPeter Tyser 93*819833afSPeter Tyser /* 94*819833afSPeter Tyser * MACRO: FExtr 95*819833afSPeter Tyser * 96*819833afSPeter Tyser * Purpose 97*819833afSPeter Tyser * The macro "FExtr" extracts the value of a bit field by masking and 98*819833afSPeter Tyser * shifting it appropriately. 99*819833afSPeter Tyser * 100*819833afSPeter Tyser * Input 101*819833afSPeter Tyser * Data Data containing the bit-field to be extracted. 102*819833afSPeter Tyser * Field Encoded bit field (using the macro "Fld"). 103*819833afSPeter Tyser * 104*819833afSPeter Tyser * Output 105*819833afSPeter Tyser * FExtr Bit-field value. 106*819833afSPeter Tyser */ 107*819833afSPeter Tyser 108*819833afSPeter Tyser #define FExtr(Data, Field) \ 109*819833afSPeter Tyser ((UData (Data) >> FShft (Field)) & FAlnMsk (Field)) 110*819833afSPeter Tyser 111*819833afSPeter Tyser 112*819833afSPeter Tyser #endif /* __BITFIELD_H */ 113