Add fifo32_peek() that returns the first element from the queue
without popping it.

Signed-off-by: Octavian Purdila <tavip@google.com>
---
 include/qemu/fifo32.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/include/qemu/fifo32.h b/include/qemu/fifo32.h
index 4e9fd1b5ef..77aab488ae 100644
--- a/include/qemu/fifo32.h
+++ b/include/qemu/fifo32.h
@@ -140,6 +140,34 @@ static inline uint32_t fifo32_pop(Fifo32 *fifo)
     return ret;
 }
 
+/**
+ * fifo32_peek:
+ * @fifo: fifo to peek at
+ *
+ * Returns the value from the FIFO's head without poping it. Behaviour
+ * is undefined if the FIFO is empty. Clients are responsible for
+ * checking for emptiness using fifo32_is_empty().
+ *
+ * Returns: the value from the FIFO's head
+ */
+
+static inline uint32_t fifo32_peek(Fifo32 *fifo)
+{
+    uint32_t ret = 0, num;
+    const uint8_t *buf;
+
+    buf = fifo8_peek_buf(&fifo->fifo, 4, &num);
+    if (num != 4) {
+        return ret;
+    }
+
+    for (int i = 0; i < sizeof(uint32_t); i++) {
+        ret |= buf[i] << (i * 8);
+    }
+
+    return ret;
+}
+
 /**
  * There is no fifo32_pop_buf() because the data is not stored in the buffer
  * as a set of native-order words.
-- 
2.46.0.295.g3b9ea8a38a-goog

Hi Octavian,

On 27/8/24 08:45, Octavian Purdila wrote:
> Add fifo32_peek() that returns the first element from the queue
> without popping it.
> 
> Signed-off-by: Octavian Purdila <tavip@google.com>
> ---
>   include/qemu/fifo32.h | 28 ++++++++++++++++++++++++++++
>   1 file changed, 28 insertions(+)
> 
> diff --git a/include/qemu/fifo32.h b/include/qemu/fifo32.h
> index 4e9fd1b5ef..77aab488ae 100644
> --- a/include/qemu/fifo32.h
> +++ b/include/qemu/fifo32.h
> @@ -140,6 +140,34 @@ static inline uint32_t fifo32_pop(Fifo32 *fifo)
>       return ret;
>   }
>   
> +/**
> + * fifo32_peek:
> + * @fifo: fifo to peek at
> + *
> + * Returns the value from the FIFO's head without poping it. Behaviour
> + * is undefined if the FIFO is empty. Clients are responsible for
> + * checking for emptiness using fifo32_is_empty().
> + *
> + * Returns: the value from the FIFO's head
> + */
> +
> +static inline uint32_t fifo32_peek(Fifo32 *fifo)

When respinning on top of Mark's Fifo8 work, please un-inline.

 e


On Fri, Sep 6, 2024 at 4:53 AM Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>
> Hi Octavian,
>

Hi Philippe,

> On 27/8/24 08:45, Octavian Purdila wrote:
> > Add fifo32_peek() that returns the first element from the queue
> > without popping it.
> >
> > Signed-off-by: Octavian Purdila <tavip@google.com>
> > ---
> >   include/qemu/fifo32.h | 28 ++++++++++++++++++++++++++++
> >   1 file changed, 28 insertions(+)
> >
> > diff --git a/include/qemu/fifo32.h b/include/qemu/fifo32.h
> > index 4e9fd1b5ef..77aab488ae 100644
> > --- a/include/qemu/fifo32.h
> > +++ b/include/qemu/fifo32.h
> > @@ -140,6 +140,34 @@ static inline uint32_t fifo32_pop(Fifo32 *fifo)
> >       return ret;
> >   }
> >
> > +/**
> > + * fifo32_peek:
> > + * @fifo: fifo to peek at
> > + *
> > + * Returns the value from the FIFO's head without poping it. Behaviour
> > + * is undefined if the FIFO is empty. Clients are responsible for
> > + * checking for emptiness using fifo32_is_empty().
> > + *
> > + * Returns: the value from the FIFO's head
> > + */
> > +
> > +static inline uint32_t fifo32_peek(Fifo32 *fifo)
>
> When respinning on top of Mark's Fifo8 work, please un-inline.
>

Do you mean to move it in a new fifo32.c file along with the other
larger functions in this header? All of the fifo32 functions are
defined as inlines.