drivers/media/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 EXPORT_SYMBOL(dvb_ringbuffer_flush);
  93
  94 void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf)
  95 {
  96         rbuf->pread = rbuf->pwrite = 0;
  97         rbuf->error = 0;
  98 }
  99
 100 void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
 101 {
 102         unsigned long flags;
 103
 104         spin_lock_irqsave(&rbuf->lock, flags);
 105         dvb_ringbuffer_flush(rbuf);
 106         spin_unlock_irqrestore(&rbuf->lock, flags);
 107
 108         wake_up(&rbuf->queue);
 109 }
 110
 111 ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf, u8 __user *buf, size_t len)
 112 {
 113         size_t todo = len;
 114         size_t split;
 115
 116         split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
 117         if (split > 0) {
 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 (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
 125                 return -EFAULT;
 126
 127         rbuf->pread = (rbuf->pread + todo) % rbuf->size;
 128
 129         return len;
 130 }
 131
 132 void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len)
 133 {
 134         size_t todo = len;
 135         size_t split;
 136
 137         split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
 138         if (split > 0) {
 139                 memcpy(buf, rbuf->data+rbuf->pread, split);
 140                 buf += split;
 141                 todo -= split;
 142                 rbuf->pread = 0;
 143         }
 144         memcpy(buf, rbuf->data+rbuf->pread, todo);
 145
 146         rbuf->pread = (rbuf->pread + todo) % rbuf->size;
 147 }
 148
 149
 150 ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
 151 {
 152         size_t todo = len;
 153         size_t split;
 154
 155         split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
 156
 157         if (split > 0) {
 158                 memcpy(rbuf->data+rbuf->pwrite, buf, split);
 159                 buf += split;
 160                 todo -= split;
 161                 rbuf->pwrite = 0;
 162         }
 163         memcpy(rbuf->data+rbuf->pwrite, buf, todo);
 164         rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;
 165
 166         return len;
 167 }
 168
 169 ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
 170 {
 171         int status;
 172         ssize_t oldpwrite = rbuf->pwrite;
 173
 174         DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
 175         DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
 176         DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
 177         status = dvb_ringbuffer_write(rbuf, buf, len);
 178
 179         if (status < 0) rbuf->pwrite = oldpwrite;
 180         return status;
 181 }
 182
 183 ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx,
 184                                 int offset, u8 __user *buf, size_t len)
 185 {
 186         size_t todo;
 187         size_t split;
 188         size_t pktlen;
 189
 190         pktlen = rbuf->data[idx] << 8;
 191         pktlen |= rbuf->data[(idx + 1) % rbuf->size];
 192         if (offset > pktlen) return -EINVAL;
 193         if ((offset + len) > pktlen) len = pktlen - offset;
 194
 195         idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
 196         todo = len;
 197         split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
 198         if (split > 0) {
 199                 if (copy_to_user(buf, rbuf->data+idx, split))
 200                         return -EFAULT;
 201                 buf += split;
 202                 todo -= split;
 203                 idx = 0;
 204         }
 205         if (copy_to_user(buf, rbuf->data+idx, todo))
 206                 return -EFAULT;
 207
 208         return len;
 209 }
 210
 211 ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
 212                                 int offset, u8* buf, size_t len)
 213 {
 214         size_t todo;
 215         size_t split;
 216         size_t pktlen;
 217
 218         pktlen = rbuf->data[idx] << 8;
 219         pktlen |= rbuf->data[(idx + 1) % rbuf->size];
 220         if (offset > pktlen) return -EINVAL;
 221         if ((offset + len) > pktlen) len = pktlen - offset;
 222
 223         idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
 224         todo = len;
 225         split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
 226         if (split > 0) {
 227                 memcpy(buf, rbuf->data+idx, split);
 228                 buf += split;
 229                 todo -= split;
 230                 idx = 0;
 231         }
 232         memcpy(buf, rbuf->data+idx, todo);
 233         return len;
 234 }
 235
 236 void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
 237 {
 238         size_t pktlen;
 239
 240         rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;
 241
 242         // clean up disposed packets
 243         while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
 244                 if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
 245                         pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
 246                         pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
 247                         DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
 248                 } else {
 249                         // first packet is not disposed, so we stop cleaning now
 250                         break;
 251                 }
 252         }
 253 }
 254
 255 ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
 256 {
 257         int consumed;
 258         int curpktlen;
 259         int curpktstatus;
 260
 261         if (idx == -1) {
 262                idx = rbuf->pread;
 263         } else {
 264                 curpktlen = rbuf->data[idx] << 8;
 265                 curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
 266                 idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
 267         }
 268
 269         consumed = (idx - rbuf->pread) % rbuf->size;
 270
 271         while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {
 272
 273                 curpktlen = rbuf->data[idx] << 8;
 274                 curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
 275                 curpktstatus = rbuf->data[(idx + 2) % rbuf->size];
 276
 277                 if (curpktstatus == PKT_READY) {
 278                         *pktlen = curpktlen;
 279                         return idx;
 280                 }
 281
 282                 consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
 283                 idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
 284         }
 285
 286         // no packets available
 287         return -1;
 288 }
 289
 290
 291
 292 EXPORT_SYMBOL(dvb_ringbuffer_init);
 293 EXPORT_SYMBOL(dvb_ringbuffer_empty);
 294 EXPORT_SYMBOL(dvb_ringbuffer_free);
 295 EXPORT_SYMBOL(dvb_ringbuffer_avail);
 296 EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
 297 EXPORT_SYMBOL(dvb_ringbuffer_read_user);
 298 EXPORT_SYMBOL(dvb_ringbuffer_read);
 299 EXPORT_SYMBOL(dvb_ringbuffer_write);