diff options
Diffstat (limited to 'include/queue.h')
| -rw-r--r-- | include/queue.h | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/include/queue.h b/include/queue.h index 29cab07383..bf952b0b53 100644 --- a/include/queue.h +++ b/include/queue.h @@ -112,26 +112,38 @@ int queue_is_full(struct queue const *q); /* * Chunk based queue access. A queue_chunk is a contiguous region of queue - * buffer bytes, not units. It may represent either free space in the queue - * or entries. + * buffer units. */ struct queue_chunk { - size_t length; - uint8_t *buffer; + size_t count; + void *buffer; }; /* * Return the largest contiguous block of free space from the tail of the - * queue. This may not be all of the available free space in the queue. Once - * some or all of the free space has been written to you must call + * queue + offset. This may not be all of the available free space in the + * queue. Once some or all of the free space has been written to you must call * queue_advance_tail to update the queue. You do not need to fill all of the * free space returned before calling queue_advance_tail, and you may call * queue_advance tail multiple times for a single chunk. But you must not * advance the tail more than the length of the chunk, or more than the actual * number of units that you have written to the free space represented by the * chunk. + * + * Since this function returns continuous space, offset will allow accessing + * writable memory that is wrapped. For example: + * + * *: Used entry + * -: Free space + * + * H T + * |--***---| + * + * A call to queue_get_write_chunk(&q, 0) will return 3 entries starting at T. + * To be able to also write the 2 leading writable indicies, we'll need to use + * queue_get_write_chunk(&q, 3), which will return 2 entries at queue index 0. */ -struct queue_chunk queue_get_write_chunk(struct queue const *q); +struct queue_chunk queue_get_write_chunk(struct queue const *q, size_t offset); /* * Return the largest contiguous block of units from the head of the queue. |