Re: [qemu-s390x] [Qemu-devel] [PATCH v1 7/7] s390x/tcg: Implement LOAD COUNT TO BLOCK BOUNDARY

[Richard Henderson]

On 2/25/19 3:55 AM, David Hildenbrand wrote:
> +uint64_t HELPER(lcbb)(uint64_t addr, uint32_t m3)
> +{
> +    const uint32_t block_size = 1ul << (m3 + 6);
> +    const uint64_t rounded_addr = ROUND_UP(addr, block_size);
> +    uint32_t to_load = 16;
> +
> +    if (rounded_addr != addr) {
> +        to_load = MIN(rounded_addr - addr, to_load);
> +    }
> +    return to_load;
> +}

I don't understand all of this "blocksize" business, when they are all powers
of two, and the maximum value returned is 16.

As far as I can see, the result is obtained by -(addr | -16) regardless of the
value of m3.


r~