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author | Peter Crosthwaite <peter.crosthwaite@xilinx.com> | 2013-04-16 10:27:16 +1000 |
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committer | Edgar E. Iglesias <edgar.iglesias@gmail.com> | 2013-04-16 10:04:23 +0200 |
commit | 35e60bfdbc14ce31bba55cc82144f8a2a82ede68 (patch) | |
tree | 2e9d9523edd263fc325a819ad6aba7d78edc4c59 /include/hw/stream.h | |
parent | 210914e29975d17e635f9e8c1f7478c0ed7a208f (diff) | |
download | qemu-35e60bfdbc14ce31bba55cc82144f8a2a82ede68.zip qemu-35e60bfdbc14ce31bba55cc82144f8a2a82ede68.tar.gz qemu-35e60bfdbc14ce31bba55cc82144f8a2a82ede68.tar.bz2 |
stream: Add flow control API
Add basic flow control to stream. A stream slave may return short, indicating
that it is not capable of accepting any more data at the present time. Polling
or a callback can be used via the can_push() function to determine when the
slave can receive again.
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Diffstat (limited to 'include/hw/stream.h')
-rw-r--r-- | include/hw/stream.h | 33 |
1 files changed, 30 insertions, 3 deletions
diff --git a/include/hw/stream.h b/include/hw/stream.h index f6137d6..5bc47a9 100644 --- a/include/hw/stream.h +++ b/include/hw/stream.h @@ -18,14 +18,41 @@ typedef struct StreamSlave { Object Parent; } StreamSlave; +typedef void (*StreamCanPushNotifyFn)(void *opaque); + typedef struct StreamSlaveClass { InterfaceClass parent; - - void (*push)(StreamSlave *obj, unsigned char *buf, size_t len, + /** + * can push - determine if a stream slave is capable of accepting at least + * one byte of data. Returns false if cannot accept. If not implemented, the + * slave is assumed to always be capable of recieveing. + * @notify: Optional callback that the slave will call when the slave is + * capable of recieving again. Only called if false is returned. + * @notify_opaque: opaque data to pass to notify call. + */ + bool (*can_push)(StreamSlave *obj, StreamCanPushNotifyFn notify, + void *notify_opaque); + /** + * push - push data to a Stream slave. The number of bytes pushed is + * returned. If the slave short returns, the master must wait before trying + * again, the slave may continue to just return 0 waiting for the vm time to + * advance. The can_push() function can be used to trap the point in time + * where the slave is ready to recieve again, otherwise polling on a QEMU + * timer will work. + * @obj: Stream slave to push to + * @buf: Data to write + * @len: Maximum number of bytes to write + */ + size_t (*push)(StreamSlave *obj, unsigned char *buf, size_t len, uint32_t *app); } StreamSlaveClass; -void +size_t stream_push(StreamSlave *sink, uint8_t *buf, size_t len, uint32_t *app); +bool +stream_can_push(StreamSlave *sink, StreamCanPushNotifyFn notify, + void *notify_opaque); + + #endif /* STREAM_H */ |