util/fifo8: Expose fifo8_pop_buf()
Extract fifo8_pop_buf() from hw/scsi/esp.c and expose
it as part of the <qemu/fifo8.h> API. This function takes
care of non-contiguous (wrapped) FIFO buffer (which is an
implementation detail).
Suggested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
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: <20240722160745.67904-7-philmd@linaro.org>
diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 7e9657e..04c9a55 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -197,39 +197,9 @@
return val;
}
-static uint32_t esp_fifo8_pop_buf(Fifo8 *fifo, uint8_t *dest, int maxlen)
-{
- const uint8_t *buf;
- uint32_t n, n2;
- int len;
-
- if (maxlen == 0) {
- return 0;
- }
-
- len = maxlen;
- buf = fifo8_pop_bufptr(fifo, len, &n);
- if (dest) {
- memcpy(dest, buf, n);
- }
-
- /* Add FIFO wraparound if needed */
- len -= n;
- len = MIN(len, fifo8_num_used(fifo));
- if (len) {
- buf = fifo8_pop_bufptr(fifo, len, &n2);
- if (dest) {
- memcpy(&dest[n], buf, n2);
- }
- n += n2;
- }
-
- return n;
-}
-
static uint32_t esp_fifo_pop_buf(ESPState *s, uint8_t *dest, int maxlen)
{
- uint32_t len = esp_fifo8_pop_buf(&s->fifo, dest, maxlen);
+ uint32_t len = fifo8_pop_buf(&s->fifo, dest, maxlen);
esp_update_drq(s);
return len;
@@ -335,7 +305,7 @@
if (!cmdlen || !s->current_dev) {
return;
}
- esp_fifo8_pop_buf(&s->cmdfifo, buf, cmdlen);
+ fifo8_pop_buf(&s->cmdfifo, buf, cmdlen);
current_lun = scsi_device_find(&s->bus, 0, s->current_dev->id, s->lun);
if (!current_lun) {
@@ -381,7 +351,7 @@
/* Ignore extended messages for now */
if (s->cmdfifo_cdb_offset) {
int len = MIN(s->cmdfifo_cdb_offset, fifo8_num_used(&s->cmdfifo));
- esp_fifo8_pop_buf(&s->cmdfifo, NULL, len);
+ fifo8_pop_buf(&s->cmdfifo, NULL, len);
s->cmdfifo_cdb_offset = 0;
}
}
diff --git a/include/qemu/fifo8.h b/include/qemu/fifo8.h
index a30220c..bca6da3 100644
--- a/include/qemu/fifo8.h
+++ b/include/qemu/fifo8.h
@@ -63,11 +63,27 @@
uint8_t fifo8_pop(Fifo8 *fifo);
/**
+ * fifo8_pop_buf:
+ * @fifo: FIFO to pop from
+ * @dest: the buffer to write the data into (can be NULL)
+ * @destlen: size of @dest and maximum number of bytes to pop
+ *
+ * Pop a number of elements from the FIFO up to a maximum of @destlen.
+ * The popped data is copied into the @dest buffer.
+ * Care is taken when the data wraps around in the ring buffer.
+ *
+ * Returns: number of bytes popped.
+ */
+uint32_t fifo8_pop_buf(Fifo8 *fifo, uint8_t *dest, uint32_t destlen);
+
+/**
* fifo8_pop_bufptr:
* @fifo: FIFO to pop from
* @max: maximum number of bytes to pop
* @numptr: pointer filled with number of bytes returned (can be NULL)
*
+ * New code should prefer to use fifo8_pop_buf() instead of fifo8_pop_bufptr().
+ *
* 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
* the internal FIFO backing store and data (without checking for overflow!)
diff --git a/util/fifo8.c b/util/fifo8.c
index 5bbb615..a250ea9 100644
--- a/util/fifo8.c
+++ b/util/fifo8.c
@@ -102,6 +102,35 @@
return fifo8_peekpop_buf(fifo, max, numptr, true);
}
+uint32_t fifo8_pop_buf(Fifo8 *fifo, uint8_t *dest, uint32_t destlen)
+{
+ const uint8_t *buf;
+ uint32_t n1, n2 = 0;
+ uint32_t len;
+
+ if (destlen == 0) {
+ return 0;
+ }
+
+ len = destlen;
+ buf = fifo8_pop_bufptr(fifo, len, &n1);
+ if (dest) {
+ memcpy(dest, buf, n1);
+ }
+
+ /* Add FIFO wraparound if needed */
+ len -= n1;
+ len = MIN(len, fifo8_num_used(fifo));
+ if (len) {
+ buf = fifo8_pop_bufptr(fifo, len, &n2);
+ if (dest) {
+ memcpy(&dest[n1], buf, n2);
+ }
+ }
+
+ return n1 + n2;
+}
+
bool fifo8_is_empty(Fifo8 *fifo)
{
return (fifo->num == 0);
