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Re: [PATCH 03/12] util/fifo8: Introduce fifo8_peek_buf()
From: |
Francisco Iglesias |
Subject: |
Re: [PATCH 03/12] util/fifo8: Introduce fifo8_peek_buf() |
Date: |
Mon, 22 May 2023 21:38:19 +0200 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
On [2023 May 22] Mon 17:31:35, Philippe Mathieu-Daudé wrote:
> To be able to poke at FIFO content without popping it,
> introduce the fifo8_peek_buf() method by factoring
> common content from fifo8_pop_buf().
>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
> include/qemu/fifo8.h | 26 ++++++++++++++++++++++++++
> util/fifo8.c | 22 ++++++++++++++++++----
> 2 files changed, 44 insertions(+), 4 deletions(-)
>
> diff --git a/include/qemu/fifo8.h b/include/qemu/fifo8.h
> index d0d02bc73d..7acf6d1347 100644
> --- a/include/qemu/fifo8.h
> +++ b/include/qemu/fifo8.h
> @@ -93,6 +93,32 @@ uint8_t fifo8_pop(Fifo8 *fifo);
> */
> const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr);
>
> +/**
> + * fifo8_peek_buf:
> + * @fifo: FIFO to poke from
> + * @max: maximum number of bytes to pop
> + * @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
s/Pop/Peek into/
> + * containing the popped data is returned. This buffer points directly into
s/popped data/data peeked into/
If above sounds good:
Reviewed-by: Francisco Iglesias <frasse.iglesias@gmail.com>
> + * the FIFO backing store and data is invalidated once any of the fifo8_*
> APIs
> + * are called on the FIFO.
(Above sounds as if it happens automatically to me but I'm not english native,
a suggestion could be to put something as below "clients are responsible for
tracking this")
> + *
> + * The function may return fewer bytes than requested when the data wraps
> + * 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 *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 peekable data.
> + */
> +const uint8_t *fifo8_peek_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr);
> +
> /**
> * fifo8_reset:
> * @fifo: FIFO to reset
> diff --git a/util/fifo8.c b/util/fifo8.c
> index 032e985440..e12477843e 100644
> --- a/util/fifo8.c
> +++ b/util/fifo8.c
> @@ -66,7 +66,8 @@ uint8_t fifo8_pop(Fifo8 *fifo)
> return ret;
> }
>
> -const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr)
> +static const uint8_t *fifo8_peekpop_buf(Fifo8 *fifo, uint32_t max,
> + uint32_t *numptr, bool do_pop)
> {
> uint8_t *ret;
> uint32_t num;
> @@ -74,15 +75,28 @@ const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max,
> uint32_t *numptr)
> assert(max > 0 && max <= fifo->num);
> num = MIN(fifo->capacity - fifo->head, max);
> ret = &fifo->data[fifo->head];
> - fifo->head += num;
> - fifo->head %= fifo->capacity;
> - fifo->num -= num;
> +
> + if (do_pop) {
> + fifo->head += num;
> + fifo->head %= fifo->capacity;
> + fifo->num -= num;
> + }
> if (numptr) {
> *numptr = num;
> }
> return ret;
> }
>
> +const uint8_t *fifo8_peek_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr)
> +{
> + return fifo8_peekpop_buf(fifo, max, numptr, false);
> +}
> +
> +const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr)
> +{
> + return fifo8_peekpop_buf(fifo, max, numptr, true);
> +}
> +
> void fifo8_reset(Fifo8 *fifo)
> {
> fifo->num = 0;
> --
> 2.38.1
>
>
- [PATCH 00/12] hw/char/pl011: Implement TX (async) FIFO to avoid blocking the main loop, Philippe Mathieu-Daudé, 2023/05/22
- [PATCH 03/12] util/fifo8: Introduce fifo8_peek_buf(), Philippe Mathieu-Daudé, 2023/05/22
- [PATCH 02/12] util/fifo8: Allow fifo8_pop_buf() to not populate popped length, Philippe Mathieu-Daudé, 2023/05/22
- [PATCH 04/12] hw/char/pl011: Display register name in trace events, Philippe Mathieu-Daudé, 2023/05/22
- [PATCH 01/12] util/fifo8: Fix typo in fifo8_push_all() description, Philippe Mathieu-Daudé, 2023/05/22
- [PATCH 05/12] hw/char/pl011: Remove duplicated PL011_INT_[RT]X definitions, Philippe Mathieu-Daudé, 2023/05/22