drivers/media/dvb/dvb-core/dvb_ringbuffer.c

   1 /*
   2  *
   3  * dvb_ringbuffer.c: 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
  10  *                       & Marcus Metzler 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
  28
  29 #define __KERNEL_SYSCALLS__
  30 #include <linux/errno.h>
  31 #include <linux/kernel.h>
  32 #include <linux/module.h>
  33 #include <linux/sched.h>
  34 #include <linux/string.h>
  35 #include <asm/uaccess.h>
  36
  37 #include "dvb_ringbuffer.h"
  38
  39 #define PKT_READY 0
  40 #define PKT_DISPOSED 1
  41
  42
  43 void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len)
  44 {
  45         rbuf->pread=rbuf->pwrite=0;
  46         rbuf->data=data;
  47         rbuf->size=len;
  48         rbuf->error=0;
  49
  50         init_waitqueue_head(&rbuf->queue);
  51
  52         spin_lock_init(&(rbuf->lock));
  53 }
  54
  55
  56
  57 int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf)
  58 {
  59         return (rbuf->pread==rbuf->pwrite);
  60 }
  61
  62
  63
  64 ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf)
  65 {
  66         ssize_t free;
  67
  68         free = rbuf->pread - rbuf->pwrite;
  69         if (free <= 0)
  70                 free += rbuf->size;
  71         return free-1;
  72 }
  73
  74
  75
  76 ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf)
  77 {
  78         ssize_t avail;
  79
  80         avail = rbuf->pwrite - rbuf->pread;
  81         if (avail < 0)
  82                 avail += rbuf->size;
  83         return avail;
  84 }
  85
  86
  87
  88 void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf)
  89 {
  90         rbuf->pread = rbuf->pwrite;
  91         rbuf->error = 0;
  92 }
  93
  94
  95
  96 void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
  97 {
  98         unsigned long flags;
  99
 100         spin_lock_irqsave(&rbuf->lock, flags);
 101         dvb_ringbuffer_flush(rbuf);
 102         spin_unlock_irqrestore(&rbuf->lock, flags);
 103
 104         wake_up(&rbuf->queue);
 105 }
 106
 107
 108
 109 ssize_t dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len, int usermem)
 110 {
 111         size_t todo = len;
 112         size_t split;
 113
 114         split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
 115         if (split > 0) {
 116                 if (!usermem)
 117                         memcpy(buf, rbuf->data+rbuf->pread, split);
 118                 else
 119                         if (copy_to_user(buf, rbuf->data+rbuf->pread, split))
 120                                 return -EFAULT;
 121                 buf += split;
 122                 todo -= split;
 123                 rbuf->pread = 0;
 124         }
 125         if (!usermem)
 126                 memcpy(buf, rbuf->data+rbuf->pread, todo);
 127         else
 128                 if (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
 129                         return -EFAULT;
 130
 131         rbuf->pread = (rbuf->pread + todo) % rbuf->size;
 132
 133         return len;
 134 }
 135
 136
 137
 138 ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
 139 {
 140         size_t todo = len;
 141         size_t split;
 142
 143         split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
 144
 145         if (split > 0) {
 146                 memcpy(rbuf->data+rbuf->pwrite, buf, split);
 147                 buf += split;
 148                 todo -= split;
 149                 rbuf->pwrite = 0;
 150         }
 151         memcpy(rbuf->data+rbuf->pwrite, buf, todo);
 152         rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;
 153
 154         return len;
 155 }
 156
 157 ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
 158 {
 159         int status;
 160         ssize_t oldpwrite = rbuf->pwrite;
 161
 162         DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
 163         DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
 164         DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
 165         status = dvb_ringbuffer_write(rbuf, buf, len);
 166
 167         if (status < 0) rbuf->pwrite = oldpwrite;
 168         return status;
 169 }
 170
 171 ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
 172                                 int offset, u8* buf, size_t len, int usermem)
 173 {
 174         size_t todo;
 175         size_t split;
 176         size_t pktlen;
 177
 178         pktlen = rbuf->data[idx] << 8;
 179         pktlen |= rbuf->data[(idx + 1) % rbuf->size];
 180         if (offset > pktlen) return -EINVAL;
 181         if ((offset + len) > pktlen) len = pktlen - offset;
 182
 183         idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
 184         todo = len;
 185         split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
 186         if (split > 0) {
 187                 if (!usermem)
 188                         memcpy(buf, rbuf->data+idx, split);
 189                 else
 190                         if (copy_to_user(buf, rbuf->data+idx, split))
 191                                 return -EFAULT;
 192                 buf += split;
 193                 todo -= split;
 194                 idx = 0;
 195         }
 196         if (!usermem)
 197                 memcpy(buf, rbuf->data+idx, todo);
 198         else
 199                 if (copy_to_user(buf, rbuf->data+idx, todo))
 200                         return -EFAULT;
 201
 202         return len;
 203 }
 204
 205 void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
 206 {
 207         size_t pktlen;
 208
 209         rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;
 210
 211         // clean up disposed packets
 212         while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
 213                 if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
 214                         pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
 215                         pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
 216                         DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
 217                 } else {
 218                         // first packet is not disposed, so we stop cleaning now
 219                         break;
 220                 }
 221         }
 222 }
 223
 224 ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
 225 {
 226         int consumed;
 227         int curpktlen;
 228         int curpktstatus;
 229
 230         if (idx == -1) {
 231                idx = rbuf->pread;
 232         } else {
 233                 curpktlen = rbuf->data[idx] << 8;
 234                 curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
 235                 idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
 236         }
 237
 238         consumed = (idx - rbuf->pread) % rbuf->size;
 239
 240         while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {
 241
 242                 curpktlen = rbuf->data[idx] << 8;
 243                 curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
 244                 curpktstatus = rbuf->data[(idx + 2) % rbuf->size];
 245
 246                 if (curpktstatus == PKT_READY) {
 247                         *pktlen = curpktlen;
 248                         return idx;
 249                 }
 250
 251                 consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
 252                 idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
 253         }
 254
 255         // no packets available
 256         return -1;
 257 }
 258
 259
 260
 261 EXPORT_SYMBOL(dvb_ringbuffer_init);
 262 EXPORT_SYMBOL(dvb_ringbuffer_empty);
 263 EXPORT_SYMBOL(dvb_ringbuffer_free);
 264 EXPORT_SYMBOL(dvb_ringbuffer_avail);
 265 EXPORT_SYMBOL(dvb_ringbuffer_flush);
 266 EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
 267 EXPORT_SYMBOL(dvb_ringbuffer_read);
 268 EXPORT_SYMBOL(dvb_ringbuffer_write);
 269 EXPORT_SYMBOL(dvb_ringbuffer_pkt_write);
 270 EXPORT_SYMBOL(dvb_ringbuffer_pkt_read);
 271 EXPORT_SYMBOL(dvb_ringbuffer_pkt_dispose);
 272 EXPORT_SYMBOL(dvb_ringbuffer_pkt_next);