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
  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 }
  91
  92
  93
  94 void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
  95 {
  96         unsigned long flags;
  97
  98         spin_lock_irqsave(&rbuf->lock, flags);
  99         dvb_ringbuffer_flush(rbuf);
 100         spin_unlock_irqrestore(&rbuf->lock, flags);
 101
 102         wake_up(&rbuf->queue);
 103 }
 104
 105
 106
 107 ssize_t dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len, int usermem)
 108 {
 109         size_t todo = len;
 110         size_t split;
 111
 112         split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
 113         if (split > 0) {
 114                 if (!usermem)
 115                         memcpy(buf, rbuf->data+rbuf->pread, split);
 116                 else
 117                         if (copy_to_user(buf, rbuf->data+rbuf->pread, split))
 118                                 return -EFAULT;
 119                 buf += split;
 120                 todo -= split;
 121                 rbuf->pread = 0;
 122         }
 123         if (!usermem)
 124                 memcpy(buf, rbuf->data+rbuf->pread, todo);
 125         else
 126                 if (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
 127                         return -EFAULT;
 128
 129         rbuf->pread = (rbuf->pread + todo) % rbuf->size;
 130
 131         return len;
 132 }
 133
 134
 135
 136 ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
 137 {
 138         size_t todo = len;
 139         size_t split;
 140
 141         split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
 142
 143         if (split > 0) {
 144                 memcpy(rbuf->data+rbuf->pwrite, buf, split);
 145                 buf += split;
 146                 todo -= split;
 147                 rbuf->pwrite = 0;
 148         }
 149         memcpy(rbuf->data+rbuf->pwrite, buf, todo);
 150         rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;
 151
 152         return len;
 153 }
 154
 155 ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
 156 {
 157         int status;
 158         ssize_t oldpwrite = rbuf->pwrite;
 159
 160         DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
 161         DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
 162         DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
 163         status = dvb_ringbuffer_write(rbuf, buf, len);
 164
 165         if (status < 0) rbuf->pwrite = oldpwrite;
 166         return status;
 167 }
 168
 169 ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
 170                                 int offset, u8* buf, size_t len, int usermem)
 171 {
 172         size_t todo;
 173         size_t split;
 174         size_t pktlen;
 175
 176         pktlen = rbuf->data[idx] << 8;
 177         pktlen |= rbuf->data[(idx + 1) % rbuf->size];
 178         if (offset > pktlen) return -EINVAL;
 179         if ((offset + len) > pktlen) len = pktlen - offset;
 180
 181         idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
 182         todo = len;
 183         split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
 184         if (split > 0) {
 185                 if (!usermem)
 186                         memcpy(buf, rbuf->data+idx, split);
 187                 else
 188                         if (copy_to_user(buf, rbuf->data+idx, split))
 189                                 return -EFAULT;
 190                 buf += split;
 191                 todo -= split;
 192                 idx = 0;
 193         }
 194         if (!usermem)
 195                 memcpy(buf, rbuf->data+idx, todo);
 196         else
 197                 if (copy_to_user(buf, rbuf->data+idx, todo))
 198                         return -EFAULT;
 199
 200         return len;
 201 }
 202
 203 void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
 204 {
 205         size_t pktlen;
 206
 207         rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;
 208
 209         // clean up disposed packets
 210         while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
 211                 if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
 212                         pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
 213                         pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
 214                         DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
 215                 } else {
 216                         // first packet is not disposed, so we stop cleaning now
 217                         break;
 218                 }
 219         }
 220 }
 221
 222 ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
 223 {
 224         int consumed;
 225         int curpktlen;
 226         int curpktstatus;
 227
 228         if (idx == -1) {
 229                idx = rbuf->pread;
 230         } else {
 231                 curpktlen = rbuf->data[idx] << 8;
 232                 curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
 233                 idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
 234         }
 235
 236         consumed = (idx - rbuf->pread) % rbuf->size;
 237
 238         while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {
 239
 240                 curpktlen = rbuf->data[idx] << 8;
 241                 curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
 242                 curpktstatus = rbuf->data[(idx + 2) % rbuf->size];
 243
 244                 if (curpktstatus == PKT_READY) {
 245                         *pktlen = curpktlen;
 246                         return idx;
 247                 }
 248
 249                 consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
 250                 idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
 251         }
 252
 253         // no packets available
 254         return -1;
 255 }
 256
 257
 258
 259 EXPORT_SYMBOL(dvb_ringbuffer_init);
 260 EXPORT_SYMBOL(dvb_ringbuffer_empty);
 261 EXPORT_SYMBOL(dvb_ringbuffer_free);
 262 EXPORT_SYMBOL(dvb_ringbuffer_avail);
 263 EXPORT_SYMBOL(dvb_ringbuffer_flush);
 264 EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
 265 EXPORT_SYMBOL(dvb_ringbuffer_read);
 266 EXPORT_SYMBOL(dvb_ringbuffer_write);
 267 EXPORT_SYMBOL(dvb_ringbuffer_pkt_write);
 268 EXPORT_SYMBOL(dvb_ringbuffer_pkt_read);
 269 EXPORT_SYMBOL(dvb_ringbuffer_pkt_dispose);
 270 EXPORT_SYMBOL(dvb_ringbuffer_pkt_next);