Merge tag 'qemu-sparc-20240110' of https://github.com/mcayland/qemu into staging
qemu-sparc queue
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# gpg: Signature made Wed 10 Jan 2024 07:00:08 GMT
# gpg: using RSA key CC621AB98E82200D915CC9C45BC2C56FAE0F321F
# gpg: issuer "mark.cave-ayland@ilande.co.uk"
# gpg: Good signature from "Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>" [full]
# Primary key fingerprint: CC62 1AB9 8E82 200D 915C C9C4 5BC2 C56F AE0F 321F
* tag 'qemu-sparc-20240110' of https://github.com/mcayland/qemu:
util/fifo8: Introduce fifo8_peek_buf()
util/fifo8: Allow fifo8_pop_buf() to not populate popped length
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/include/qemu/fifo8.h b/include/qemu/fifo8.h
index 16be02f..c6295c6 100644
--- a/include/qemu/fifo8.h
+++ b/include/qemu/fifo8.h
@@ -71,7 +71,7 @@
* 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 +82,43 @@
* 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_peek_buf: read upto max bytes from the fifo
+ * @fifo: FIFO to read from
+ * @max: maximum number of bytes to peek
+ * @numptr: pointer filled with number of bytes returned (can be NULL)
+ *
+ * Peek into a number of elements from the FIFO up to a maximum of max.
+ * The buffer containing the data peeked into is returned. This buffer points
+ * directly into the FIFO backing store. Since data is invalidated once any
+ * of the fifo8_* APIs are called on the FIFO, it is the caller responsibility
+ * to access it before doing further API calls.
+ *
+ * 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:
diff --git a/util/fifo8.c b/util/fifo8.c
index de8fd0f..4e01b53 100644
--- a/util/fifo8.c
+++ b/util/fifo8.c
@@ -66,19 +66,37 @@
return ret;
}
-const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *num)
+static const uint8_t *fifo8_peekpop_buf(Fifo8 *fifo, uint32_t max,
+ uint32_t *numptr, bool do_pop)
{
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 %= 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;
