1a09e64fbSRussell King /* 2a09e64fbSRussell King * FILE bitfield.h 3a09e64fbSRussell King * 4a09e64fbSRussell King * Version 1.1 5a09e64fbSRussell King * Author Copyright (c) Marc A. Viredaz, 1998 6a09e64fbSRussell King * DEC Western Research Laboratory, Palo Alto, CA 7a09e64fbSRussell King * Date April 1998 (April 1997) 8a09e64fbSRussell King * System Advanced RISC Machine (ARM) 9a09e64fbSRussell King * Language C or ARM Assembly 10a09e64fbSRussell King * Purpose Definition of macros to operate on bit fields. 11a09e64fbSRussell King */ 12a09e64fbSRussell King 13a09e64fbSRussell King 14a09e64fbSRussell King 15a09e64fbSRussell King #ifndef __BITFIELD_H 16a09e64fbSRussell King #define __BITFIELD_H 17a09e64fbSRussell King 18a09e64fbSRussell King #ifndef __ASSEMBLY__ 19a09e64fbSRussell King #define UData(Data) ((unsigned long) (Data)) 20a09e64fbSRussell King #else 21a09e64fbSRussell King #define UData(Data) (Data) 22a09e64fbSRussell King #endif 23a09e64fbSRussell King 24a09e64fbSRussell King 25a09e64fbSRussell King /* 26a09e64fbSRussell King * MACRO: Fld 27a09e64fbSRussell King * 28a09e64fbSRussell King * Purpose 29a09e64fbSRussell King * The macro "Fld" encodes a bit field, given its size and its shift value 30a09e64fbSRussell King * with respect to bit 0. 31a09e64fbSRussell King * 32a09e64fbSRussell King * Note 33a09e64fbSRussell King * A more intuitive way to encode bit fields would have been to use their 34a09e64fbSRussell King * mask. However, extracting size and shift value information from a bit 35a09e64fbSRussell King * field's mask is cumbersome and might break the assembler (255-character 36a09e64fbSRussell King * line-size limit). 37a09e64fbSRussell King * 38a09e64fbSRussell King * Input 39a09e64fbSRussell King * Size Size of the bit field, in number of bits. 40a09e64fbSRussell King * Shft Shift value of the bit field with respect to bit 0. 41a09e64fbSRussell King * 42a09e64fbSRussell King * Output 43a09e64fbSRussell King * Fld Encoded bit field. 44a09e64fbSRussell King */ 45a09e64fbSRussell King 46a09e64fbSRussell King #define Fld(Size, Shft) (((Size) << 16) + (Shft)) 47a09e64fbSRussell King 48a09e64fbSRussell King 49a09e64fbSRussell King /* 50a09e64fbSRussell King * MACROS: FSize, FShft, FMsk, FAlnMsk, F1stBit 51a09e64fbSRussell King * 52a09e64fbSRussell King * Purpose 53a09e64fbSRussell King * The macros "FSize", "FShft", "FMsk", "FAlnMsk", and "F1stBit" return 54a09e64fbSRussell King * the size, shift value, mask, aligned mask, and first bit of a 55a09e64fbSRussell King * bit field. 56a09e64fbSRussell King * 57a09e64fbSRussell King * Input 58a09e64fbSRussell King * Field Encoded bit field (using the macro "Fld"). 59a09e64fbSRussell King * 60a09e64fbSRussell King * Output 61a09e64fbSRussell King * FSize Size of the bit field, in number of bits. 62a09e64fbSRussell King * FShft Shift value of the bit field with respect to bit 0. 63a09e64fbSRussell King * FMsk Mask for the bit field. 64a09e64fbSRussell King * FAlnMsk Mask for the bit field, aligned on bit 0. 65a09e64fbSRussell King * F1stBit First bit of the bit field. 66a09e64fbSRussell King */ 67a09e64fbSRussell King 68a09e64fbSRussell King #define FSize(Field) ((Field) >> 16) 69a09e64fbSRussell King #define FShft(Field) ((Field) & 0x0000FFFF) 70a09e64fbSRussell King #define FMsk(Field) (((UData (1) << FSize (Field)) - 1) << FShft (Field)) 71a09e64fbSRussell King #define FAlnMsk(Field) ((UData (1) << FSize (Field)) - 1) 72a09e64fbSRussell King #define F1stBit(Field) (UData (1) << FShft (Field)) 73a09e64fbSRussell King 74a09e64fbSRussell King 75a09e64fbSRussell King /* 76a09e64fbSRussell King * MACRO: FInsrt 77a09e64fbSRussell King * 78a09e64fbSRussell King * Purpose 79a09e64fbSRussell King * The macro "FInsrt" inserts a value into a bit field by shifting the 80a09e64fbSRussell King * former appropriately. 81a09e64fbSRussell King * 82a09e64fbSRussell King * Input 83a09e64fbSRussell King * Value Bit-field value. 84a09e64fbSRussell King * Field Encoded bit field (using the macro "Fld"). 85a09e64fbSRussell King * 86a09e64fbSRussell King * Output 87a09e64fbSRussell King * FInsrt Bit-field value positioned appropriately. 88a09e64fbSRussell King */ 89a09e64fbSRussell King 90a09e64fbSRussell King #define FInsrt(Value, Field) \ 91a09e64fbSRussell King (UData (Value) << FShft (Field)) 92a09e64fbSRussell King 93a09e64fbSRussell King 94a09e64fbSRussell King /* 95a09e64fbSRussell King * MACRO: FExtr 96a09e64fbSRussell King * 97a09e64fbSRussell King * Purpose 98a09e64fbSRussell King * The macro "FExtr" extracts the value of a bit field by masking and 99a09e64fbSRussell King * shifting it appropriately. 100a09e64fbSRussell King * 101a09e64fbSRussell King * Input 102a09e64fbSRussell King * Data Data containing the bit-field to be extracted. 103a09e64fbSRussell King * Field Encoded bit field (using the macro "Fld"). 104a09e64fbSRussell King * 105a09e64fbSRussell King * Output 106a09e64fbSRussell King * FExtr Bit-field value. 107a09e64fbSRussell King */ 108a09e64fbSRussell King 109a09e64fbSRussell King #define FExtr(Data, Field) \ 110a09e64fbSRussell King ((UData (Data) >> FShft (Field)) & FAlnMsk (Field)) 111a09e64fbSRussell King 112a09e64fbSRussell King 113a09e64fbSRussell King #endif /* __BITFIELD_H */ 114