| /* |
| * |
| * dvb_ringbuffer.h: ring buffer implementation for the dvb driver |
| * |
| * Copyright (C) 2003 Oliver Endriss |
| * Copyright (C) 2004 Andrew de Quincey |
| * |
| * based on code originally found in av7110.c & dvb_ci.c: |
| * Copyright (C) 1999-2003 Ralph Metzler & Marcus Metzler |
| * for convergence integrated media GmbH |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public License |
| * as published by the Free Software Foundation; either version 2.1 |
| * of the License, or (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| */ |
| |
| #ifndef _DVB_RINGBUFFER_H_ |
| #define _DVB_RINGBUFFER_H_ |
| |
| #include <linux/spinlock.h> |
| #include <linux/wait.h> |
| |
| struct dvb_ringbuffer { |
| u8 *data; |
| ssize_t size; |
| ssize_t pread; |
| ssize_t pwrite; |
| int error; |
| |
| wait_queue_head_t queue; |
| spinlock_t lock; |
| }; |
| |
| #define DVB_RINGBUFFER_PKTHDRSIZE 3 |
| |
| |
| /* |
| ** 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); |
| |
| /* test whether buffer is empty */ |
| extern int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf); |
| |
| /* return the number of free bytes in the buffer */ |
| extern ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf); |
| |
| /* return the number of bytes waiting in the buffer */ |
| 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 |
| */ |
| extern void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf); |
| |
| |
| /* read routines & macros */ |
| /* ---------------------- */ |
| /* flush buffer */ |
| 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 */ |
| #define DVB_RINGBUFFER_PEEK(rbuf,offs) \ |
| (rbuf)->data[((rbuf)->pread+(offs))%(rbuf)->size] |
| |
| /* 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 |
| */ |
| 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, |
| u8 *buf, size_t len); |
| |
| |
| /* write routines & macros */ |
| /* ----------------------- */ |
| /* write single byte to ring buffer */ |
| #define DVB_RINGBUFFER_WRITE_BYTE(rbuf,byte) \ |
| { (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 |
| */ |
| extern ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, |
| size_t len); |
| extern ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf, |
| const u8 __user *buf, size_t len); |
| |
| |
| /** |
| * 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). |
| * 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. |
| * 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); |
| 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. |
| * |
| * <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. |
| * |
| * <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); |
| |
| |
| #endif /* _DVB_RINGBUFFER_H_ */ |