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git.ipfire.org Git - people/ms/u-boot.git/blob - include/bitfield.h
2 * Copyright 2013 Broadcom Corporation.
4 * SPDX-License-Identifier: GPL-2.0+
10 * These are generic bitfield operations which allow manipulation of variable
11 * width bitfields within a word. One use of this would be to use data tables
12 * to determine how to reprogram fields within R/W hardware registers.
17 * +--------+----+---+--+-----+----------+
19 * +--------+----+---+--+-----+----------+
22 * +--------+----+---+--+-----+----------+
24 * +--------+----+---+--+-----+----------+
26 * mask = bitfield_mask(10, 5);
27 * old = bitfield_extract(old_reg_val, 10, 5);
28 * new_reg_val = bitfield_replace(old_reg_val, 10, 5, new);
30 * The numbers 10 and 5 could for example come from data
31 * tables which describe all bitfields in all registers.
34 #include <linux/types.h>
36 /* Produces a mask of set bits covering a range of a uint value */
37 static inline uint
bitfield_mask(uint shift
, uint width
)
39 return ((1 << width
) - 1) << shift
;
42 /* Extract the value of a bitfield found within a given register value */
43 static inline uint
bitfield_extract(uint reg_val
, uint shift
, uint width
)
45 return (reg_val
& bitfield_mask(shift
, width
)) >> shift
;
49 * Replace the value of a bitfield found within a given register value
50 * Returns the newly modified uint value with the replaced field.
52 static inline uint
bitfield_replace(uint reg_val
, uint shift
, uint width
,
55 uint mask
= bitfield_mask(shift
, width
);
57 return (reg_val
& ~mask
) | (bitfield_val
<< shift
);