diff options
Diffstat (limited to 'drivers/media/dvb-core/dvb_ringbuffer.h')
| -rw-r--r-- | drivers/media/dvb-core/dvb_ringbuffer.h | 135 |
1 files changed, 75 insertions, 60 deletions
diff --git a/drivers/media/dvb-core/dvb_ringbuffer.h b/drivers/media/dvb-core/dvb_ringbuffer.h index 9e1e11b7c39c..3ebc2d34b4a2 100644 --- a/drivers/media/dvb-core/dvb_ringbuffer.h +++ b/drivers/media/dvb-core/dvb_ringbuffer.h @@ -45,33 +45,33 @@ struct dvb_ringbuffer { /* -** Notes: -** ------ -** (1) For performance reasons read and write routines don't check buffer sizes -** and/or number of bytes free/available. This has to be done before these -** routines are called. For example: -** -** *** write <buflen> bytes *** -** free = dvb_ringbuffer_free(rbuf); -** if (free >= buflen) -** count = dvb_ringbuffer_write(rbuf, buffer, buflen); -** else -** ... -** -** *** read min. 1000, max. <bufsize> bytes *** -** avail = dvb_ringbuffer_avail(rbuf); -** if (avail >= 1000) -** count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize)); -** else -** ... -** -** (2) If there is exactly one reader and one writer, there is no need -** to lock read or write operations. -** Two or more readers must be locked against each other. -** Flushing the buffer counts as a read operation. -** Resetting the buffer counts as a read and write operation. -** Two or more writers must be locked against each other. -*/ + * Notes: + * ------ + * (1) For performance reasons read and write routines don't check buffer sizes + * and/or number of bytes free/available. This has to be done before these + * routines are called. For example: + * + * *** write @buflen: bytes *** + * free = dvb_ringbuffer_free(rbuf); + * if (free >= buflen) + * count = dvb_ringbuffer_write(rbuf, buffer, buflen); + * else + * ... + * + * *** read min. 1000, max. @bufsize: bytes *** + * avail = dvb_ringbuffer_avail(rbuf); + * if (avail >= 1000) + * count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize)); + * else + * ... + * + * (2) If there is exactly one reader and one writer, there is no need + * to lock read or write operations. + * Two or more readers must be locked against each other. + * Flushing the buffer counts as a read operation. + * Resetting the buffer counts as a read and write operation. + * Two or more writers must be locked against each other. + */ /* initialize ring buffer, lock and queue */ extern void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len); @@ -87,9 +87,9 @@ extern ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf); /* -** Reset the read and write pointers to zero and flush the buffer -** This counts as a read and write operation -*/ + * Reset the read and write pointers to zero and flush the buffer + * This counts as a read and write operation + */ extern void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf); @@ -101,19 +101,19 @@ extern void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf); /* flush buffer protected by spinlock and wake-up waiting task(s) */ extern void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf); -/* peek at byte <offs> in the buffer */ +/* peek at byte @offs: in the buffer */ #define DVB_RINGBUFFER_PEEK(rbuf,offs) \ (rbuf)->data[((rbuf)->pread+(offs))%(rbuf)->size] -/* advance read ptr by <num> bytes */ +/* advance read ptr by @num: bytes */ #define DVB_RINGBUFFER_SKIP(rbuf,num) \ (rbuf)->pread=((rbuf)->pread+(num))%(rbuf)->size /* -** read <len> bytes from ring buffer into <buf> -** <usermem> specifies whether <buf> resides in user space -** returns number of bytes transferred or -EFAULT -*/ + * read @len: bytes from ring buffer into @buf: + * @usermem: specifies whether @buf: resides in user space + * returns number of bytes transferred or -EFAULT + */ extern ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf, u8 __user *buf, size_t len); extern void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, @@ -127,9 +127,9 @@ extern void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, { (rbuf)->data[(rbuf)->pwrite]=(byte); \ (rbuf)->pwrite=((rbuf)->pwrite+1)%(rbuf)->size; } /* -** write <len> bytes to ring buffer -** <usermem> specifies whether <buf> resides in user space -** returns number of bytes transferred or -EFAULT + * write @len: bytes to ring buffer + * @usermem: specifies whether @buf: resides in user space + * returns number of bytes transferred or -EFAULT */ extern ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len); @@ -138,48 +138,63 @@ extern ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf, /** - * Write a packet into the ringbuffer. + * dvb_ringbuffer_pkt_write - Write a packet into the ringbuffer. * - * <rbuf> Ringbuffer to write to. - * <buf> Buffer to write. - * <len> Length of buffer (currently limited to 65535 bytes max). + * @rbuf: Ringbuffer to write to. + * @buf: Buffer to write. + * @len: Length of buffer (currently limited to 65535 bytes max). * returns Number of bytes written, or -EFAULT, -ENOMEM, -EVINAL. */ extern ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len); /** - * Read from a packet in the ringbuffer. Note: unlike dvb_ringbuffer_read(), this - * does NOT update the read pointer in the ringbuffer. You must use - * dvb_ringbuffer_pkt_dispose() to mark a packet as no longer required. - * - * <rbuf> Ringbuffer concerned. - * <idx> Packet index as returned by dvb_ringbuffer_pkt_next(). - * <offset> Offset into packet to read from. - * <buf> Destination buffer for data. - * <len> Size of destination buffer. - * <usermem> Set to 1 if <buf> is in userspace. + * dvb_ringbuffer_pkt_read_user - Read from a packet in the ringbuffer. + * Note: unlike dvb_ringbuffer_read(), this does NOT update the read pointer + * in the ringbuffer. You must use dvb_ringbuffer_pkt_dispose() to mark a + * packet as no longer required. + * + * @rbuf: Ringbuffer concerned. + * @idx: Packet index as returned by dvb_ringbuffer_pkt_next(). + * @offset: Offset into packet to read from. + * @buf: Destination buffer for data. + * @len: Size of destination buffer. + * * returns Number of bytes read, or -EFAULT. */ extern ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx, int offset, u8 __user *buf, size_t len); + +/** + * dvb_ringbuffer_pkt_read - Read from a packet in the ringbuffer. + * Note: unlike dvb_ringbuffer_read_user(), this DOES update the read pointer + * in the ringbuffer. + * + * @rbuf: Ringbuffer concerned. + * @idx: Packet index as returned by dvb_ringbuffer_pkt_next(). + * @offset: Offset into packet to read from. + * @buf: Destination buffer for data. + * @len: Size of destination buffer. + * + * returns Number of bytes read, or -EFAULT. + */ extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx, int offset, u8 *buf, size_t len); /** - * Dispose of a packet in the ring buffer. + * dvb_ringbuffer_pkt_dispose - Dispose of a packet in the ring buffer. * - * <rbuf> Ring buffer concerned. - * <idx> Packet index as returned by dvb_ringbuffer_pkt_next(). + * @rbuf: Ring buffer concerned. + * @idx: Packet index as returned by dvb_ringbuffer_pkt_next(). */ extern void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx); /** - * Get the index of the next packet in a ringbuffer. + * dvb_ringbuffer_pkt_next - Get the index of the next packet in a ringbuffer. * - * <rbuf> Ringbuffer concerned. - * <idx> Previous packet index, or -1 to return the first packet index. - * <pktlen> On success, will be updated to contain the length of the packet in bytes. + * @rbuf: Ringbuffer concerned. + * @idx: Previous packet index, or -1 to return the first packet index. + * @pktlen: On success, will be updated to contain the length of the packet in bytes. * returns Packet index (if >=0), or -1 if no packets available. */ extern ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen); |