Re: [PATCH 02/12] util/fifo8: Allow fifo8_pop_buf() to not populate popped length

[Francisco Iglesias]

On [2023 May 22] Mon 17:31:34, Philippe Mathieu-Daudé wrote:
> There might be cases where we know the number of bytes we can
> pop from the FIFO, or we simply don't care how many bytes is
> returned. Allow fifo8_pop_buf() to take a NULL numptr.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Reviewed-by: Francisco Iglesias <frasse.iglesias@gmail.com>


> ---
>  include/qemu/fifo8.h | 10 +++++-----
>  util/fifo8.c         | 12 ++++++++----
>  2 files changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/include/qemu/fifo8.h b/include/qemu/fifo8.h
> index 16be02f361..d0d02bc73d 100644
> --- a/include/qemu/fifo8.h
> +++ b/include/qemu/fifo8.h
> @@ -71,7 +71,7 @@ uint8_t fifo8_pop(Fifo8 *fifo);
>   * fifo8_pop_buf:
>   * @fifo: FIFO to pop from
>   * @max: maximum number of bytes to pop
> - * @num: actual number of returned bytes
> + * @numptr: pointer filled with number of bytes returned (can be NULL)
>   *
>   * Pop a number of elements from the FIFO up to a maximum of max. The buffer
>   * containing the popped data is returned. This buffer points directly into
> @@ -82,16 +82,16 @@ uint8_t fifo8_pop(Fifo8 *fifo);
>   * around in the ring buffer; in this case only a contiguous part of the data
>   * is returned.
>   *
> - * The number of valid bytes returned is populated in *num; will always 
> return
> - * at least 1 byte. max must not be 0 or greater than the number of bytes in
> - * the FIFO.
> + * The number of valid bytes returned is populated in *numptr; will always
> + * return at least 1 byte. max must not be 0 or greater than the number of
> + * bytes in the FIFO.
>   *
>   * Clients are responsible for checking the availability of requested data
>   * using fifo8_num_used().
>   *
>   * Returns: A pointer to popped data.
>   */
> -const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *num);
> +const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr);
>  
>  /**
>   * fifo8_reset:
> diff --git a/util/fifo8.c b/util/fifo8.c
> index d4d1c135e0..032e985440 100644
> --- a/util/fifo8.c
> +++ b/util/fifo8.c
> @@ -66,16 +66,20 @@ uint8_t fifo8_pop(Fifo8 *fifo)
>      return ret;
>  }
>  
> -const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *num)
> +const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr)
>  {
>      uint8_t *ret;
> +    uint32_t num;
>  
>      assert(max > 0 && max <= fifo->num);
> -    *num = MIN(fifo->capacity - fifo->head, max);
> +    num = MIN(fifo->capacity - fifo->head, max);
>      ret = &fifo->data[fifo->head];
> -    fifo->head += *num;
> +    fifo->head += num;
>      fifo->head %= fifo->capacity;
> -    fifo->num -= *num;
> +    fifo->num -= num;
> +    if (numptr) {
> +        *numptr = num;
> +    }
>      return ret;
>  }
>  
> -- 
> 2.38.1
> 
>