linux/lib/packing.c

// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/* Copyright 2016-2018 NXP
 * Copyright (c) 2018-2019, Vladimir Oltean <[email protected]>
 */
#include <linux/packing.h>
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/bitrev.h>

static int get_le_offset(int offset)
{ … }

static int get_reverse_lsw32_offset(int offset, size_t len)
{ … }

static void adjust_for_msb_right_quirk(u64 *to_write, int *box_start_bit,
				       int *box_end_bit, u8 *box_mask)
{ … }

/**
 * packing - Convert numbers (currently u64) between a packed and an unpacked
 *	     format. Unpacked means laid out in memory in the CPU's native
 *	     understanding of integers, while packed means anything else that
 *	     requires translation.
 *
 * @pbuf: Pointer to a buffer holding the packed value.
 * @uval: Pointer to an u64 holding the unpacked value.
 * @startbit: The index (in logical notation, compensated for quirks) where
 *	      the packed value starts within pbuf. Must be larger than, or
 *	      equal to, endbit.
 * @endbit: The index (in logical notation, compensated for quirks) where
 *	    the packed value ends within pbuf. Must be smaller than, or equal
 *	    to, startbit.
 * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf.
 * @op: If PACK, then uval will be treated as const pointer and copied (packed)
 *	into pbuf, between startbit and endbit.
 *	If UNPACK, then pbuf will be treated as const pointer and the logical
 *	value between startbit and endbit will be copied (unpacked) to uval.
 * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and
 *	    QUIRK_MSB_ON_THE_RIGHT.
 *
 * Return: 0 on success, EINVAL or ERANGE if called incorrectly. Assuming
 *	   correct usage, return code may be discarded.
 *	   If op is PACK, pbuf is modified.
 *	   If op is UNPACK, uval is modified.
 */
int packing(void *pbuf, u64 *uval, int startbit, int endbit, size_t pbuflen,
	    enum packing_op op, u8 quirks)
{ … }
EXPORT_SYMBOL(…);

MODULE_DESCRIPTION(…) …;