1 /* SPDX-License-Identifier: BSD-3-Clause
2 * Copyright 2016-2018 NXP
3 * Copyright (c) 2018-2019, Vladimir Oltean <olteanv@gmail.com>
4 */
5 #ifndef _LINUX_PACKING_H
6 #define _LINUX_PACKING_H
7
8 #include <linux/types.h>
9 #include <linux/bitops.h>
10
11 #define QUIRK_MSB_ON_THE_RIGHT BIT(0)
12 #define QUIRK_LITTLE_ENDIAN BIT(1)
13 #define QUIRK_LSW32_IS_FIRST BIT(2)
14
15 enum packing_op {
16 PACK,
17 UNPACK,
18 };
19
20 /**
21 * packing - Convert numbers (currently u64) between a packed and an unpacked
22 * format. Unpacked means laid out in memory in the CPU's native
23 * understanding of integers, while packed means anything else that
24 * requires translation.
25 *
26 * @pbuf: Pointer to a buffer holding the packed value.
27 * @uval: Pointer to an u64 holding the unpacked value.
28 * @startbit: The index (in logical notation, compensated for quirks) where
29 * the packed value starts within pbuf. Must be larger than, or
30 * equal to, endbit.
31 * @endbit: The index (in logical notation, compensated for quirks) where
32 * the packed value ends within pbuf. Must be smaller than, or equal
33 * to, startbit.
34 * @op: If PACK, then uval will be treated as const pointer and copied (packed)
35 * into pbuf, between startbit and endbit.
36 * If UNPACK, then pbuf will be treated as const pointer and the logical
37 * value between startbit and endbit will be copied (unpacked) to uval.
38 * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and
39 * QUIRK_MSB_ON_THE_RIGHT.
40 *
41 * Return: 0 on success, EINVAL or ERANGE if called incorrectly. Assuming
42 * correct usage, return code may be discarded.
43 * If op is PACK, pbuf is modified.
44 * If op is UNPACK, uval is modified.
45 */
46 int packing(void *pbuf, u64 *uval, int startbit, int endbit, size_t pbuflen,
47 enum packing_op op, u8 quirks);
48
49 #endif
50
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