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host-utils: add 128-bit quotient support to divu128/divs128

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These will be used to implement new decimal floating point
instructions from Power ISA 3.1.

The remainder is now returned directly by divu128/divs128,
freeing up phigh to receive the high 64 bits of the quotient.

Signed-off-by: Luis Pires <luis.pires@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211025191154.350831-4-luis.pires@eldorado.org.br>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Luis Pires 2021-10-25 16:11:38 -03:00 • committed by Richard Henderson
parent 8ac2d6c526
commit 40f3e79a86
4 changed files with 108 additions and 60 deletions
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6
include/hw/clock.h
View file

@ -323,11 +323,7 @@ static inline uint64_t clock_ns_to_ticks(const Clock *clk, uint64_t ns)
if (clk->period == 0) {
return 0;
}
/*
* BUG: when CONFIG_INT128 is not defined, the current implementation of
* divu128 does not return a valid truncated quotient, so the result will
* be wrong.
*/
divu128(&lo, &hi, clk->period);
return lo;
}

20
include/qemu/host-utils.h
View file

@ -56,26 +56,32 @@ static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
return (__int128_t)a * b / c;
}
static inline void divu128(uint64_t *plow, uint64_t *phigh, uint64_t divisor)
static inline uint64_t divu128(uint64_t *plow, uint64_t *phigh,
uint64_t divisor)
{
__uint128_t dividend = ((__uint128_t)*phigh << 64) | *plow;
__uint128_t result = dividend / divisor;
*plow = result;
*phigh = dividend % divisor;
*phigh = result >> 64;
return dividend % divisor;
}
static inline void divs128(int64_t *plow, int64_t *phigh, int64_t divisor)
static inline int64_t divs128(uint64_t *plow, int64_t *phigh,
int64_t divisor)
{
__int128_t dividend = ((__int128_t)*phigh << 64) | (uint64_t)*plow;
__int128_t dividend = ((__int128_t)*phigh << 64) | *plow;
__int128_t result = dividend / divisor;
*plow = result;
*phigh = dividend % divisor;
*phigh = result >> 64;
return dividend % divisor;
}
#else
void muls64(uint64_t *plow, uint64_t *phigh, int64_t a, int64_t b);
void mulu64(uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b);
void divu128(uint64_t *plow, uint64_t *phigh, uint64_t divisor);
void divs128(int64_t *plow, int64_t *phigh, int64_t divisor);
uint64_t divu128(uint64_t *plow, uint64_t *phigh, uint64_t divisor);
int64_t divs128(uint64_t *plow, int64_t *phigh, int64_t divisor);
static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
{