Logo Search packages:      
Sourcecode: linux version File versions  Download package

dvb_ringbuffer.c

/*
 *
 * dvb_ringbuffer.c: ring buffer implementation for the dvb driver
 *
 * Copyright (C) 2003 Oliver Endriss
 * Copyright (C) 2004 Andrew de Quincey
 *
 * based on code originally found in av7110.c & dvb_ci.c:
 * Copyright (C) 1999-2003 Ralph  Metzler
 *                       & Marcus Metzler for convergence integrated media GmbH
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */



#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <asm/uaccess.h>

#include "dvb_ringbuffer.h"

#define PKT_READY 0
#define PKT_DISPOSED 1


void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len)
{
      rbuf->pread=rbuf->pwrite=0;
      rbuf->data=data;
      rbuf->size=len;
      rbuf->error=0;

      init_waitqueue_head(&rbuf->queue);

      spin_lock_init(&(rbuf->lock));
}



int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf)
{
      return (rbuf->pread==rbuf->pwrite);
}



ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf)
{
      ssize_t free;

      free = rbuf->pread - rbuf->pwrite;
      if (free <= 0)
            free += rbuf->size;
      return free-1;
}



ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf)
{
      ssize_t avail;

      avail = rbuf->pwrite - rbuf->pread;
      if (avail < 0)
            avail += rbuf->size;
      return avail;
}



void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf)
{
      rbuf->pread = rbuf->pwrite;
      rbuf->error = 0;
}



void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
{
      unsigned long flags;

      spin_lock_irqsave(&rbuf->lock, flags);
      dvb_ringbuffer_flush(rbuf);
      spin_unlock_irqrestore(&rbuf->lock, flags);

      wake_up(&rbuf->queue);
}



ssize_t dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len, int usermem)
{
      size_t todo = len;
      size_t split;

      split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
      if (split > 0) {
            if (!usermem)
                  memcpy(buf, rbuf->data+rbuf->pread, split);
            else
                  if (copy_to_user(buf, rbuf->data+rbuf->pread, split))
                        return -EFAULT;
            buf += split;
            todo -= split;
            rbuf->pread = 0;
      }
      if (!usermem)
            memcpy(buf, rbuf->data+rbuf->pread, todo);
      else
            if (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
                  return -EFAULT;

      rbuf->pread = (rbuf->pread + todo) % rbuf->size;

      return len;
}



ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
{
      size_t todo = len;
      size_t split;

      split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;

      if (split > 0) {
            memcpy(rbuf->data+rbuf->pwrite, buf, split);
            buf += split;
            todo -= split;
            rbuf->pwrite = 0;
      }
      memcpy(rbuf->data+rbuf->pwrite, buf, todo);
      rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;

      return len;
}

ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
{
      int status;
      ssize_t oldpwrite = rbuf->pwrite;

      DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
      DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
      DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
      status = dvb_ringbuffer_write(rbuf, buf, len);

      if (status < 0) rbuf->pwrite = oldpwrite;
      return status;
}

ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
                        int offset, u8* buf, size_t len, int usermem)
{
      size_t todo;
      size_t split;
      size_t pktlen;

      pktlen = rbuf->data[idx] << 8;
      pktlen |= rbuf->data[(idx + 1) % rbuf->size];
      if (offset > pktlen) return -EINVAL;
      if ((offset + len) > pktlen) len = pktlen - offset;

      idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
      todo = len;
      split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
      if (split > 0) {
            if (!usermem)
                  memcpy(buf, rbuf->data+idx, split);
            else
                  if (copy_to_user(buf, rbuf->data+idx, split))
                        return -EFAULT;
            buf += split;
            todo -= split;
            idx = 0;
      }
      if (!usermem)
            memcpy(buf, rbuf->data+idx, todo);
      else
            if (copy_to_user(buf, rbuf->data+idx, todo))
                  return -EFAULT;

      return len;
}

void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
{
      size_t pktlen;

      rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;

      // clean up disposed packets
      while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
            if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
                  pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
                  pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
                  DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
            } else {
                  // first packet is not disposed, so we stop cleaning now
                  break;
            }
      }
}

ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
{
      int consumed;
      int curpktlen;
      int curpktstatus;

      if (idx == -1) {
             idx = rbuf->pread;
      } else {
            curpktlen = rbuf->data[idx] << 8;
            curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
            idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
      }

      consumed = (idx - rbuf->pread) % rbuf->size;

      while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {

            curpktlen = rbuf->data[idx] << 8;
            curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
            curpktstatus = rbuf->data[(idx + 2) % rbuf->size];

            if (curpktstatus == PKT_READY) {
                  *pktlen = curpktlen;
                  return idx;
            }

            consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
            idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
      }

      // no packets available
      return -1;
}



EXPORT_SYMBOL(dvb_ringbuffer_init);
EXPORT_SYMBOL(dvb_ringbuffer_empty);
EXPORT_SYMBOL(dvb_ringbuffer_free);
EXPORT_SYMBOL(dvb_ringbuffer_avail);
EXPORT_SYMBOL(dvb_ringbuffer_flush);
EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
EXPORT_SYMBOL(dvb_ringbuffer_read);
EXPORT_SYMBOL(dvb_ringbuffer_write);
EXPORT_SYMBOL(dvb_ringbuffer_pkt_write);
EXPORT_SYMBOL(dvb_ringbuffer_pkt_read);
EXPORT_SYMBOL(dvb_ringbuffer_pkt_dispose);
EXPORT_SYMBOL(dvb_ringbuffer_pkt_next);

Generated by  Doxygen 1.6.0   Back to index