As this platform can do multiply/divide using 128 bit precision use these instructions to implement it.
Signed-off-by: Frediano Ziglio <frediano.zig...@huawei.com> --- include/qemu-common.h | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/include/qemu-common.h b/include/qemu-common.h index f3033ae..880659d 100644 --- a/include/qemu-common.h +++ b/include/qemu-common.h @@ -370,11 +370,23 @@ static inline uint8_t from_bcd(uint8_t val) } /* compute with 96 bit intermediate result: (a*b)/c */ -#ifdef CONFIG_INT128 +#if defined(CONFIG_INT128) && !defined(__x86_64__) static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c) { return (__int128)a * b / c; } +#elif defined(__x86_64__) +/* Optimised x64 version. This assume that a*b/c fits in 64 bit */ +static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c) +{ + uint64_t res; + + asm ("mulq %2\n\tdivq %3" + : "=a"(res) + : "a"(a), "qm"((uint64_t) b), "qm"((uint64_t)c) + : "rdx", "cc"); + return res; +} #else static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c) { -- 1.9.1