OpenE2K/qemu-e2k
13
4
Fork 0
Code Issues 4 Pull Requests Projects 2 Releases Activity

host-utils: Introduce mulu128

Browse Source 
Signed-off-by: Luis Pires <luis.pires@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211029192417.400707-6-luis.pires@eldorado.org.br>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Luis Pires 2021-10-29 16:24:07 -03:00 committed by David Gibson
parent d39b2cc7d0
commit e06049f380
1 changed files with 36 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
include/qemu/host-utils.h
View File

@ -590,6 +590,42 @@ static inline bool umul64_overflow(uint64_t x, uint64_t y, uint64_t *ret)
#endif
}
/*
* Unsigned 128x64 multiplication.
* Returns true if the result got truncated to 128 bits.
* Otherwise, returns false and the multiplication result via plow and phigh.
*/
static inline bool mulu128(uint64_t *plow, uint64_t *phigh, uint64_t factor)
{
#if defined(CONFIG_INT128) && \
(__has_builtin(__builtin_mul_overflow) || __GNUC__ >= 5)
bool res;
__uint128_t r;
__uint128_t f = ((__uint128_t)*phigh << 64) | *plow;
res = __builtin_mul_overflow(f, factor, &r);
*plow = r;
*phigh = r >> 64;
return res;
#else
uint64_t dhi = *phigh;
uint64_t dlo = *plow;
uint64_t ahi;
uint64_t blo, bhi;
if (dhi == 0) {
mulu64(plow, phigh, dlo, factor);
return false;
}
mulu64(plow, &ahi, dlo, factor);
mulu64(&blo, &bhi, dhi, factor);
return uadd64_overflow(ahi, blo, phigh) || bhi != 0;
#endif
}
/**
* uadd64_carry - addition with carry-in and carry-out
* @x, @y: addends