util/fifo8: Introduce fifo8_drop()

Add the fifo8_drop() helper for clarity.
It is a simple wrapper over fifo8_pop_buf().

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-Id: <20240722160745.67904-8-philmd@linaro.org>

hw/scsi/esp.c

@@ -351,7 +351,7 @@ static void do_message_phase(ESPState *s)
     /* Ignore extended messages for now */
     if (s->cmdfifo_cdb_offset) {
         int len = MIN(s->cmdfifo_cdb_offset, fifo8_num_used(&s->cmdfifo));
-        fifo8_pop_buf(&s->cmdfifo, NULL, len);
+        fifo8_drop(&s->cmdfifo, len);
         s->cmdfifo_cdb_offset = 0;
     }
 }

include/qemu/fifo8.h

@@ -131,6 +131,15 @@ const uint8_t *fifo8_pop_bufptr(Fifo8 *fifo, uint32_t max, uint32_t *numptr);
  */
 const uint8_t *fifo8_peek_bufptr(Fifo8 *fifo, uint32_t max, uint32_t *numptr);
 
+/**
+ * fifo8_drop:
+ * @fifo: FIFO to drop bytes
+ * @len: number of bytes to drop
+ *
+ * Drop (consume) bytes from a FIFO.
+ */
+void fifo8_drop(Fifo8 *fifo, uint32_t len);
+
 /**
  * fifo8_reset:
  * @fifo: FIFO to reset

util/fifo8.c

@@ -131,6 +131,12 @@ uint32_t fifo8_pop_buf(Fifo8 *fifo, uint8_t *dest, uint32_t destlen)
     return n1 + n2;
 }
 
+void fifo8_drop(Fifo8 *fifo, uint32_t len)
+{
+    len -= fifo8_pop_buf(fifo, NULL, len);
+    assert(len == 0);
+}
+
 bool fifo8_is_empty(Fifo8 *fifo)
 {
     return (fifo->num == 0);