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+/*
+ * FILE bitfield.h
+ *
+ * Version 1.1
+ * Author Copyright (c) Marc A. Viredaz, 1998
+ * DEC Western Research Laboratory, Palo Alto, CA
+ * Date April 1998 (April 1997)
+ * System Advanced RISC Machine (ARM)
+ * Language C or ARM Assembly
+ * Purpose Definition of macros to operate on bit fields.
+ */
+
+
+
+#ifndef __BITFIELD_H
+#define __BITFIELD_H
+
+#ifndef __ASSEMBLY__
+#define UData(Data) ((unsigned long) (Data))
+#else
+#define UData(Data) (Data)
+#endif
+
+
+/*
+ * MACRO: Fld
+ *
+ * Purpose
+ * The macro "Fld" encodes a bit field, given its size and its shift value
+ * with respect to bit 0.
+ *
+ * Note
+ * A more intuitive way to encode bit fields would have been to use their
+ * mask. However, extracting size and shift value information from a bit
+ * field's mask is cumbersome and might break the assembler (255-character
+ * line-size limit).
+ *
+ * Input
+ * Size Size of the bit field, in number of bits.
+ * Shft Shift value of the bit field with respect to bit 0.
+ *
+ * Output
+ * Fld Encoded bit field.
+ */
+
+#define Fld(Size, Shft) (((Size) << 16) + (Shft))
+
+
+/*
+ * MACROS: FSize, FShft, FMsk, FAlnMsk, F1stBit
+ *
+ * Purpose
+ * The macros "FSize", "FShft", "FMsk", "FAlnMsk", and "F1stBit" return
+ * the size, shift value, mask, aligned mask, and first bit of a
+ * bit field.
+ *
+ * Input
+ * Field Encoded bit field (using the macro "Fld").
+ *
+ * Output
+ * FSize Size of the bit field, in number of bits.
+ * FShft Shift value of the bit field with respect to bit 0.
+ * FMsk Mask for the bit field.
+ * FAlnMsk Mask for the bit field, aligned on bit 0.
+ * F1stBit First bit of the bit field.
+ */
+
+#define FSize(Field) ((Field) >> 16)
+#define FShft(Field) ((Field) & 0x0000FFFF)
+#define FMsk(Field) (((UData (1) << FSize (Field)) - 1) << FShft (Field))
+#define FAlnMsk(Field) ((UData (1) << FSize (Field)) - 1)
+#define F1stBit(Field) (UData (1) << FShft (Field))
+
+
+/*
+ * MACRO: FInsrt
+ *
+ * Purpose
+ * The macro "FInsrt" inserts a value into a bit field by shifting the
+ * former appropriately.
+ *
+ * Input
+ * Value Bit-field value.
+ * Field Encoded bit field (using the macro "Fld").
+ *
+ * Output
+ * FInsrt Bit-field value positioned appropriately.
+ */
+
+#define FInsrt(Value, Field) \
+ (UData (Value) << FShft (Field))
+
+
+/*
+ * MACRO: FExtr
+ *
+ * Purpose
+ * The macro "FExtr" extracts the value of a bit field by masking and
+ * shifting it appropriately.
+ *
+ * Input
+ * Data Data containing the bit-field to be extracted.
+ * Field Encoded bit field (using the macro "Fld").
+ *
+ * Output
+ * FExtr Bit-field value.
+ */
+
+#define FExtr(Data, Field) \
+ ((UData (Data) >> FShft (Field)) & FAlnMsk (Field))
+
+
+#endif /* __BITFIELD_H */