/* * * dvb_ringbuffer.c: ring buffer implementation for the dvb driver * * Copyright (C) 2003 Oliver Endriss  *  * based on code originally found in av7110.c: * Copyright (C) 1999-2002 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. */#define __KERNEL_SYSCALLS__#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"void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len){        rbuf->pread=rbuf->pwrite=0;        rbuf->data=data;        rbuf->size=len;        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;}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, int usermem){        size_t todo = len;        size_t split;            split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;        if (split > 0) {                if (!usermem)                         memcpy(rbuf->data+rbuf->pwrite, buf, split);                else                        if (copy_from_user(rbuf->data+rbuf->pwrite,                                            buf, split))                                return -EFAULT;                buf += split;                todo -= split;                rbuf->pwrite = 0;        }        if (!usermem)                 memcpy(rbuf->data+rbuf->pwrite, buf, todo);        else                if (copy_from_user(rbuf->data+rbuf->pwrite, buf, todo))                         return -EFAULT;        rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;	return len;}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);