1/* 2 * 3 * dvb_ringbuffer.h: ring buffer implementation for the dvb driver 4 * 5 * Copyright (C) 2003 Oliver Endriss 6 * Copyright (C) 2004 Andrew de Quincey 7 * 8 * based on code originally found in av7110.c & dvb_ci.c: 9 * Copyright (C) 1999-2003 Ralph Metzler & Marcus Metzler 10 * for convergence integrated media GmbH 11 * 12 * This program is free software; you can redistribute it and/or 13 * modify it under the terms of the GNU Lesser General Public License 14 * as published by the Free Software Foundation; either version 2.1 15 * of the License, or (at your option) any later version. 16 * 17 * This program is distributed in the hope that it will be useful, 18 * but WITHOUT ANY WARRANTY; without even the implied warranty of 19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 20 * GNU Lesser General Public License for more details. 21 * 22 * You should have received a copy of the GNU Lesser General Public License 23 * along with this program; if not, write to the Free Software 24 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 25 */ 26 27#ifndef _DVB_RINGBUFFER_H_ 28#define _DVB_RINGBUFFER_H_ 29 30#include <linux/spinlock.h> 31#include <linux/wait.h> 32 33struct dvb_ringbuffer { 34 u8 *data; 35 ssize_t size; 36 ssize_t pread; 37 ssize_t pwrite; 38 int error; 39 40 wait_queue_head_t queue; 41 spinlock_t lock; 42}; 43 44#define DVB_RINGBUFFER_PKTHDRSIZE 3 45 46 47/* 48 * Notes: 49 * ------ 50 * (1) For performance reasons read and write routines don't check buffer sizes 51 * and/or number of bytes free/available. This has to be done before these 52 * routines are called. For example: 53 * 54 * *** write @buflen: bytes *** 55 * free = dvb_ringbuffer_free(rbuf); 56 * if (free >= buflen) 57 * count = dvb_ringbuffer_write(rbuf, buffer, buflen); 58 * else 59 * ... 60 * 61 * *** read min. 1000, max. @bufsize: bytes *** 62 * avail = dvb_ringbuffer_avail(rbuf); 63 * if (avail >= 1000) 64 * count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize)); 65 * else 66 * ... 67 * 68 * (2) If there is exactly one reader and one writer, there is no need 69 * to lock read or write operations. 70 * Two or more readers must be locked against each other. 71 * Flushing the buffer counts as a read operation. 72 * Resetting the buffer counts as a read and write operation. 73 * Two or more writers must be locked against each other. 74 */ 75 76/* initialize ring buffer, lock and queue */ 77extern void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len); 78 79/* test whether buffer is empty */ 80extern int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf); 81 82/* return the number of free bytes in the buffer */ 83extern ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf); 84 85/* return the number of bytes waiting in the buffer */ 86extern ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf); 87 88 89/* 90 * Reset the read and write pointers to zero and flush the buffer 91 * This counts as a read and write operation 92 */ 93extern void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf); 94 95 96/* read routines & macros */ 97/* ---------------------- */ 98/* flush buffer */ 99extern void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf); 100 101/* flush buffer protected by spinlock and wake-up waiting task(s) */ 102extern void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf); 103 104/* peek at byte @offs: in the buffer */ 105#define DVB_RINGBUFFER_PEEK(rbuf,offs) \ 106 (rbuf)->data[((rbuf)->pread+(offs))%(rbuf)->size] 107 108/* advance read ptr by @num: bytes */ 109#define DVB_RINGBUFFER_SKIP(rbuf,num) \ 110 (rbuf)->pread=((rbuf)->pread+(num))%(rbuf)->size 111 112/* 113 * read @len: bytes from ring buffer into @buf: 114 * @usermem: specifies whether @buf: resides in user space 115 * returns number of bytes transferred or -EFAULT 116 */ 117extern ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf, 118 u8 __user *buf, size_t len); 119extern void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, 120 u8 *buf, size_t len); 121 122 123/* write routines & macros */ 124/* ----------------------- */ 125/* write single byte to ring buffer */ 126#define DVB_RINGBUFFER_WRITE_BYTE(rbuf,byte) \ 127 { (rbuf)->data[(rbuf)->pwrite]=(byte); \ 128 (rbuf)->pwrite=((rbuf)->pwrite+1)%(rbuf)->size; } 129/* 130 * write @len: bytes to ring buffer 131 * @usermem: specifies whether @buf: resides in user space 132 * returns number of bytes transferred or -EFAULT 133*/ 134extern ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, 135 size_t len); 136extern ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf, 137 const u8 __user *buf, size_t len); 138 139 140/** 141 * dvb_ringbuffer_pkt_write - Write a packet into the ringbuffer. 142 * 143 * @rbuf: Ringbuffer to write to. 144 * @buf: Buffer to write. 145 * @len: Length of buffer (currently limited to 65535 bytes max). 146 * returns Number of bytes written, or -EFAULT, -ENOMEM, -EVINAL. 147 */ 148extern ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, 149 size_t len); 150 151/** 152 * dvb_ringbuffer_pkt_read_user - Read from a packet in the ringbuffer. 153 * Note: unlike dvb_ringbuffer_read(), this does NOT update the read pointer 154 * in the ringbuffer. You must use dvb_ringbuffer_pkt_dispose() to mark a 155 * packet as no longer required. 156 * 157 * @rbuf: Ringbuffer concerned. 158 * @idx: Packet index as returned by dvb_ringbuffer_pkt_next(). 159 * @offset: Offset into packet to read from. 160 * @buf: Destination buffer for data. 161 * @len: Size of destination buffer. 162 * 163 * returns Number of bytes read, or -EFAULT. 164 */ 165extern ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx, 166 int offset, u8 __user *buf, size_t len); 167 168/** 169 * dvb_ringbuffer_pkt_read - Read from a packet in the ringbuffer. 170 * Note: unlike dvb_ringbuffer_read_user(), this DOES update the read pointer 171 * in the ringbuffer. 172 * 173 * @rbuf: Ringbuffer concerned. 174 * @idx: Packet index as returned by dvb_ringbuffer_pkt_next(). 175 * @offset: Offset into packet to read from. 176 * @buf: Destination buffer for data. 177 * @len: Size of destination buffer. 178 * 179 * returns Number of bytes read, or -EFAULT. 180 */ 181extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx, 182 int offset, u8 *buf, size_t len); 183 184/** 185 * dvb_ringbuffer_pkt_dispose - Dispose of a packet in the ring buffer. 186 * 187 * @rbuf: Ring buffer concerned. 188 * @idx: Packet index as returned by dvb_ringbuffer_pkt_next(). 189 */ 190extern void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx); 191 192/** 193 * dvb_ringbuffer_pkt_next - Get the index of the next packet in a ringbuffer. 194 * 195 * @rbuf: Ringbuffer concerned. 196 * @idx: Previous packet index, or -1 to return the first packet index. 197 * @pktlen: On success, will be updated to contain the length of the packet in bytes. 198 * returns Packet index (if >=0), or -1 if no packets available. 199 */ 200extern ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen); 201 202 203#endif /* _DVB_RINGBUFFER_H_ */ 204