mirror of
https://github.com/RIOT-OS/RIOT.git
synced 2024-12-29 04:50:03 +01:00
a6623f834f
Currently the bitfield type mixes up the order of bits: While the byte order is big-endian (most significant byte first), the bit order of each single byte within the bitfield is little-endian (most significant bit last). While this isn't a problem for most applications of the bitfield type it becomes one when sending the bitfield over the network (as done e.g. in the [ACKs of Selective Fragment Recovery][SFR-ACKs]). This change unifies byte order and bit order to both be most significant bX first. [SFR-ACKs]: https://tools.ietf.org/html/draft-ietf-6lo-fragment-recovery-07
111 lines
2.5 KiB
C
111 lines
2.5 KiB
C
/*
|
|
* Copyright (C) 2015 INRIA
|
|
*
|
|
* This file is subject to the terms and conditions of the GNU Lesser
|
|
* General Public License v2.1. See the file LICENSE in the top level
|
|
* directory for more details.
|
|
*/
|
|
|
|
/**
|
|
* @defgroup sys_bitfield Bitfields
|
|
* @ingroup sys
|
|
* @brief Bitfields of arbitrary length
|
|
*
|
|
* The bitfields in this module have their most significant bytes first and
|
|
* their most significant bits within each byte of the bitfield also first.
|
|
*
|
|
* @file
|
|
* @{
|
|
*
|
|
* @brief bitfields operations on bitfields of arbitrary length
|
|
*
|
|
* @note Code taken mostly from
|
|
* <a href="http://stackoverflow.com/questions/1590893/error-trying-to-define-a-1-024-bit-128-byte-bit-field">
|
|
* Stackoverflow, User Christoph</a>
|
|
*
|
|
* @author Oliver Hahm <oliver.hahm@inria.fr>
|
|
*/
|
|
|
|
#ifndef BITFIELD_H
|
|
#define BITFIELD_H
|
|
|
|
#include <stdint.h>
|
|
#include <stdbool.h>
|
|
#include <stddef.h>
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
/**
|
|
* @brief Declare a bitfield of a given size
|
|
*
|
|
* @note SIZE should be a constant expression. This avoids variable length
|
|
* arrays.
|
|
*/
|
|
#define BITFIELD(NAME, SIZE) uint8_t NAME[((SIZE) + 7) / 8]
|
|
|
|
/**
|
|
* @brief Set the bit to 1
|
|
*
|
|
* @param[in,out] field The bitfield
|
|
* @param[in] idx The number of the bit to set
|
|
*/
|
|
static inline void bf_set(uint8_t field[], size_t idx)
|
|
{
|
|
field[idx / 8] |= (1u << (7 - (idx % 8)));
|
|
}
|
|
|
|
/**
|
|
* @brief Clear the bit
|
|
*
|
|
* @param[in,out] field The bitfield
|
|
* @param[in] idx The number of the bit to clear
|
|
*/
|
|
static inline void bf_unset(uint8_t field[], size_t idx)
|
|
{
|
|
field[idx / 8] &= ~(1u << (7 - (idx % 8)));
|
|
}
|
|
|
|
/**
|
|
* @brief Toggle the bit
|
|
*
|
|
* @param[in,out] field The bitfield
|
|
* @param[in] idx The number of the bit to toggle
|
|
*/
|
|
static inline void bf_toggle(uint8_t field[], size_t idx)
|
|
{
|
|
field[idx / 8] ^= (1u << (7 - (idx % 8)));
|
|
}
|
|
|
|
/**
|
|
* @brief Check if the bet is set
|
|
*
|
|
* @param[in,out] field The bitfield
|
|
* @param[in] idx The number of the bit to check
|
|
*/
|
|
static inline bool bf_isset(uint8_t field[], size_t idx)
|
|
{
|
|
return (field[idx / 8] & (1u << (7 - (idx % 8))));
|
|
}
|
|
|
|
/**
|
|
* @brief Atomically get the number of an unset bit and set it
|
|
*
|
|
* This function can be used to record e.g., empty entries in an array.
|
|
*
|
|
* @param[in,out] field The bitfield
|
|
* @param[in] size The size of the bitfield
|
|
*
|
|
* @return number of bit that was set
|
|
* @return -1 if no bit was unset
|
|
*/
|
|
int bf_get_unset(uint8_t field[], int size);
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
/** @} */
|
|
#endif /* BITFIELD_H */
|