/* * * dvb_ringbuffer.h: ring buffer implementation for the dvb driver * * Copyright (C) 2003 Oliver Endriss * Copyright (C) 2004 Andrew de Quincey * * Copyright (c) 2012,2014 The Linux Foundation. All rights reserved. * * 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 #include 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 bytes *** ** free = dvb_ringbuffer_free(rbuf); ** if (free >= buflen) ** count = dvb_ringbuffer_write(rbuf, buffer, buflen); ** else ** ... ** ** *** read min. 1000, max. 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 in the buffer */ #define DVB_RINGBUFFER_PEEK(rbuf,offs) \ (rbuf)->data[((rbuf)->pread+(offs))%(rbuf)->size] /* advance read ptr by bytes */ #define DVB_RINGBUFFER_SKIP(rbuf,num) \ (rbuf)->pread = ((rbuf)->pread+(num))%(rbuf)->size /* advance write ptr by bytes */ #define DVB_RINGBUFFER_PUSH(rbuf, num) \ ((rbuf)->pwrite = (((rbuf)->pwrite+(num))%(rbuf)->size)) /* ** read bytes from ring buffer into ** specifies whether 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 bytes to ring buffer ** specifies whether 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. * * Ringbuffer to write to. * Buffer to write. * 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. * * Ringbuffer concerned. * Packet index as returned by dvb_ringbuffer_pkt_next(). * Offset into packet to read from. * Destination buffer for data. * Size of destination buffer. * Set to 1 if 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. * * Ring buffer concerned. * 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. * * Ringbuffer concerned. * Previous packet index, or -1 to return the first packet index. * 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); /** * Start a new packet that will be written directly by the user to the packet buffer. * The function only writes the header of the packet into the packet buffer, * and the packet is in pending state (can't be read by the reader) until it is * closed using dvb_ringbuffer_pkt_close. You must write the data into the * packet buffer using dvb_ringbuffer_write followed by * dvb_ringbuffer_pkt_close. * * Ringbuffer concerned. * Size of the packet's data * returns Index of the packet's header that was started. */ extern ssize_t dvb_ringbuffer_pkt_start(struct dvb_ringbuffer *rbuf, size_t len); /** * Close a packet that was started using dvb_ringbuffer_pkt_start. * The packet will be marked as ready to be ready. * * Ringbuffer concerned. * Packet index that was returned by dvb_ringbuffer_pkt_start * returns error status, -EINVAL if the provided index is invalid */ extern int dvb_ringbuffer_pkt_close(struct dvb_ringbuffer *rbuf, ssize_t idx); #endif /* _DVB_RINGBUFFER_H_ */