On 09/01/2015 12:25, Frediano Ziglio wrote:
> /* 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;
> +}
Reorder it the other way, and you can simplify the first #if.
I applied patch 1 locally, and will send a pull request once the tree is
thawed.
Paolo
