util/fifo8: Make all read-only methods const-correct

Allows these methods to be used in const contexts, i.e. where the parent
of the fifo itself is const. This is in particular useful for Rust code.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20260305220911.131508-5-shentey@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

include/qemu/fifo8.h

@@ -71,7 +71,7 @@ uint8_t fifo8_pop(Fifo8 *fifo);
  *
  * Returns: The peeked data byte.
  */
-uint8_t fifo8_peek(Fifo8 *fifo);
+uint8_t fifo8_peek(const Fifo8 *fifo);
 
 /**
  * fifo8_pop_buf:
@@ -181,7 +181,7 @@ void fifo8_reset(Fifo8 *fifo);
  *
  * Returns: True if the fifo is empty, false otherwise.
  */
-bool fifo8_is_empty(Fifo8 *fifo);
+bool fifo8_is_empty(const Fifo8 *fifo);
 
 /**
  * fifo8_is_full:
@@ -191,7 +191,7 @@ bool fifo8_is_empty(Fifo8 *fifo);
  *
  * Returns: True if the fifo is full, false otherwise.
  */
-bool fifo8_is_full(Fifo8 *fifo);
+bool fifo8_is_full(const Fifo8 *fifo);
 
 /**
  * fifo8_num_free:
@@ -201,7 +201,7 @@ bool fifo8_is_full(Fifo8 *fifo);
  *
  * Returns: Number of free bytes.
  */
-uint32_t fifo8_num_free(Fifo8 *fifo);
+uint32_t fifo8_num_free(const Fifo8 *fifo);
 
 /**
  * fifo8_num_used:
@@ -211,7 +211,7 @@ uint32_t fifo8_num_free(Fifo8 *fifo);
  *
  * Returns: Number of used bytes.
  */
-uint32_t fifo8_num_used(Fifo8 *fifo);
+uint32_t fifo8_num_used(const Fifo8 *fifo);
 
 extern const VMStateDescription vmstate_fifo8;
 

util/fifo8.c

@@ -71,7 +71,7 @@ uint8_t fifo8_pop(Fifo8 *fifo)
     return ret;
 }
 
-uint8_t fifo8_peek(Fifo8 *fifo)
+uint8_t fifo8_peek(const Fifo8 *fifo)
 {
     assert(fifo->num > 0);
     return fifo->data[fifo->head];
@@ -157,22 +157,22 @@ void fifo8_drop(Fifo8 *fifo, uint32_t len)
     assert(len == 0);
 }
 
-bool fifo8_is_empty(Fifo8 *fifo)
+bool fifo8_is_empty(const Fifo8 *fifo)
 {
     return (fifo->num == 0);
 }
 
-bool fifo8_is_full(Fifo8 *fifo)
+bool fifo8_is_full(const Fifo8 *fifo)
 {
     return (fifo->num == fifo->capacity);
 }
 
-uint32_t fifo8_num_free(Fifo8 *fifo)
+uint32_t fifo8_num_free(const Fifo8 *fifo)
 {
     return fifo->capacity - fifo->num;
 }
 
-uint32_t fifo8_num_used(Fifo8 *fifo)
+uint32_t fifo8_num_used(const Fifo8 *fifo)
 {
     return fifo->num;
 }