/* * * 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);  /** * 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_ */