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); 136 137 138/** 139 * Write a packet into the ringbuffer. 140 * 141 * <rbuf> Ringbuffer to write to. 142 * <buf> Buffer to write. 143 * <len> Length of buffer (currently limited to 65535 bytes max). 144 * returns Number of bytes written, or -EFAULT, -ENOMEM, -EVINAL. 145 */ 146extern ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, 147 size_t len); 148 149/** 150 * Read from a packet in the ringbuffer. Note: unlike dvb_ringbuffer_read(), this 151 * does NOT update the read pointer in the ringbuffer. You must use 152 * dvb_ringbuffer_pkt_dispose() to mark a packet as no longer required. 153 * 154 * <rbuf> Ringbuffer concerned. 155 * <idx> Packet index as returned by dvb_ringbuffer_pkt_next(). 156 * <offset> Offset into packet to read from. 157 * <buf> Destination buffer for data. 158 * <len> Size of destination buffer. 159 * <usermem> Set to 1 if <buf> is in userspace. 160 * returns Number of bytes read, or -EFAULT. 161 */ 162extern ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx, 163 int offset, u8 __user *buf, size_t len); 164extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx, 165 int offset, u8 *buf, size_t len); 166 167/** 168 * Dispose of a packet in the ring buffer. 169 * 170 * <rbuf> Ring buffer concerned. 171 * <idx> Packet index as returned by dvb_ringbuffer_pkt_next(). 172 */ 173extern void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx); 174 175/** 176 * Get the index of the next packet in a ringbuffer. 177 * 178 * <rbuf> Ringbuffer concerned. 179 * <idx> Previous packet index, or -1 to return the first packet index. 180 * <pktlen> On success, will be updated to contain the length of the packet in bytes. 181 * returns Packet index (if >=0), or -1 if no packets available. 182 */ 183extern ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen); 184 185 186#endif /* _DVB_RINGBUFFER_H_ */ 187