Re: [Qemu-devel] [RFC 03/29] qemu_ram_block_host_offset

[Michael S. Tsirkin]

On Wed, Jun 28, 2017 at 08:00:21PM +0100, 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                    | 6 ++++++
>  include/exec/cpu-common.h | 1 +
>  2 files changed, 7 insertions(+)
> 
> diff --git a/exec.c b/exec.c
> index 4e61226a16..a1499b9bee 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -2218,6 +2218,12 @@ 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)
> +{
> +    return (uint8_t *)host - (uint8_t *)rb->host;
> +}
> +

I'd also assert that it's within that block.

>  /*
>   * 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 4af179b543..fa1ec22d66 100644
> --- a/include/exec/cpu-common.h
> +++ b/include/exec/cpu-common.h
> @@ -66,6 +66,7 @@ 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);
> -- 
> 2.13.0