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