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