Date: Sat, 9 Jul 2022 18:26:37 +0200 From: Marc Veldman <marc@bumblingdork.com> To: freebsd-hackers@freebsd.org Subject: Canonical way / best practice for 128-bit integers Message-ID: <86CB4C22-9CAB-4578-8F11-962B4B08F756@bumblingdork.com>
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Hello,
I’m working on some bluetooth code, and that involves handling 128-bit uuids.
There are various ways to handle in the FreeBSD codebase, like in sdp.h:
/*
* SDP int128/uint128 parameter
*/
struct int128 {
int8_t b[16];
};
typedef struct int128 int128_t;
typedef struct int128 uint128_t;
and in sys/dev/random/uint128.h
#ifdef USE_REAL_UINT128_T
typedef __uint128_t uint128_t;
#define UINT128_ZERO 0ULL
#else
typedef struct {
/* Ignore endianness */
uint64_t u128t_word0;
uint64_t u128t_word1;
} uint128_t;
static const uint128_t very_long_zero = {0UL,0UL};
#define UINT128_ZERO very_long_zero
#endif
Is there any recommended / standard way to handle 128 bit integers in a portable way?
Best regards,
Marc Veldman
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