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