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-rw-r--r--drivers/media/dvb-core/dvb_ringbuffer.h186
1 files changed, 186 insertions, 0 deletions
diff --git a/drivers/media/dvb-core/dvb_ringbuffer.h b/drivers/media/dvb-core/dvb_ringbuffer.h
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+/*
+ *
+ * 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_ */

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