linux/include/linux/bcd.h
Ahmad Fatoum 1940979657 include/linux/bcd.h: provide bcd_is_valid() helper
bcd2bin(0x0A) happily returns 10, despite this being an invalid BCD
value. RTC drivers converting possibly corrupted BCD timestamps might
want to validate their input before calling bcd2bin().

Provide a macro to do so. Unlike bcd2bin and bin2bcd, out-of-line
versions are not implemented. Should the macro experience enough use,
this can be retrofitted.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Link: https://lore.kernel.org/r/20221123095527.2771434-2-s.hauer@pengutronix.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2023-02-09 23:01:49 +01:00

28 lines
683 B
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BCD_H
#define _BCD_H
#include <linux/compiler.h>
#define bcd2bin(x) \
(__builtin_constant_p((u8 )(x)) ? \
const_bcd2bin(x) : \
_bcd2bin(x))
#define bin2bcd(x) \
(__builtin_constant_p((u8 )(x)) ? \
const_bin2bcd(x) : \
_bin2bcd(x))
#define bcd_is_valid(x) \
const_bcd_is_valid(x)
#define const_bcd2bin(x) (((x) & 0x0f) + ((x) >> 4) * 10)
#define const_bin2bcd(x) ((((x) / 10) << 4) + (x) % 10)
#define const_bcd_is_valid(x) (((x) & 0x0f) < 10 && ((x) >> 4) < 10)
unsigned _bcd2bin(unsigned char val) __attribute_const__;
unsigned char _bin2bcd(unsigned val) __attribute_const__;
#endif /* _BCD_H */