Re: [Qemu-devel] [RFC v2 04/32] qemu_ram_block_host_offset

[Philippe Mathieu-Daudé]

Hi David,

On 08/24/2017 04:27 PM, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> Utility to give the offset of a host pointer within a RAMBlock
> (assuming we already know it's in that RAMBlock)
>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> ---
>   exec.c                    | 10 ++++++++++
>   include/exec/cpu-common.h |  1 +
>   2 files changed, 11 insertions(+)
>
> diff --git a/exec.c b/exec.c
> index 67df2909ce..35b4cea2ed 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -2231,6 +2231,16 @@ static void *qemu_ram_ptr_length(RAMBlock *ram_block, 
> ram_addr_t addr,
>       return ramblock_ptr(block, addr);
>   }
>   
> +/* Return the offset of a hostpointer within a ramblock */
> +ram_addr_t qemu_ram_block_host_offset(RAMBlock *rb, void *host)
> +{
> +    ram_addr_t res = (uint8_t *)host - (uint8_t *)rb->host;

What about using ptrdiff_t here,

> +    assert((uint8_t *)host >= (uint8_t *)rb->host);

and uintptr_t here?

> +    assert(res < rb->max_length);
> +
> +    return res;
> +}
> +
>   /*
>    * Translates a host ptr back to a RAMBlock, a ram_addr and an offset
>    * in that RAMBlock.
> diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
> index 74341b19d2..0d861a6289 100644
> --- a/include/exec/cpu-common.h
> +++ b/include/exec/cpu-common.h
> @@ -68,6 +68,7 @@ ram_addr_t qemu_ram_addr_from_host(void *ptr);
>   RAMBlock *qemu_ram_block_by_name(const char *name);
>   RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,
>                                      ram_addr_t *offset);
> +ram_addr_t qemu_ram_block_host_offset(RAMBlock *rb, void *host);
>   void qemu_ram_set_idstr(RAMBlock *block, const char *name, DeviceState *dev);
>   void qemu_ram_unset_idstr(RAMBlock *block);
>   const char *qemu_ram_get_idstr(RAMBlock *rb);