Re: [PATCH v1 2/2] doc: clarify the window index usage in bbdev

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 8/26/25 9:43 PM, Nicolas Chautru wrote:
> Clarify the usage, range and mapping for the set of window
> indexes of each cyclic shift for the FFT processing pipeline.
> 
> Signed-off-by: Nicolas Chautru <nicolas.chautru@intel.com>
> ---
>   doc/guides/prog_guide/bbdev.rst | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/doc/guides/prog_guide/bbdev.rst b/doc/guides/prog_guide/bbdev.rst
> index 6f1f3f65fb..064c2b1fe6 100644
> --- a/doc/guides/prog_guide/bbdev.rst
> +++ b/doc/guides/prog_guide/bbdev.rst
> @@ -296,8 +296,11 @@ Capabilities details for FFT function
>   
>   The total number of distinct time windows supported
>   for the post-FFT point-wise multiplication is exposed as ``fft_windows_num``.
> -The ``window_index`` provided for each cyclic shift
> -in each ``rte_bbdev_op_fft`` operation is expected to be limited to that size.
> +The ``window_index`` provided for each cyclic shift in each ``rte_bbdev_op_fft`` operation is
> +expected to be within the range (0 to ``fft_windows_num`` - 1).
> +These indexes for up to 12 cyclic shifts are mapped consecutively into an array of 6 bytes
> +(ie. the first index is the first 4 most significant bits of the first byte, etc...):
> +``uint8_t window_index[RTE_BBDEV_MAX_CS_2]``.
>   
>   The information related to the width of each of these pre-configured window
>   is also exposed using the ``fft_window_width`` array.

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime