packing.h 1.8 KB

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