drivers/media/video/videocodec.c - fp2-dev/kernel/msm - Gitiles

 /*
  * VIDEO MOTION CODECs internal API for video devices
  *
  * Interface for MJPEG (and maybe later MPEG/WAVELETS) codec's
  * bound to a master device.
  *
  * (c) 2002 Wolfgang Scherr <scherr@net4you.at>
  *
  * $Id: videocodec.c,v 1.1.2.8 2003/03/29 07:16:04 rbultje Exp $
  *
  * ------------------------------------------------------------------------
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 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 General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  *
  * ------------------------------------------------------------------------
  */

 #define VIDEOCODEC_VERSION "v0.2"

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/slab.h>

 // kernel config is here (procfs flag)
 #include <linux/config.h>

 #ifdef CONFIG_PROC_FS
 #include <linux/proc_fs.h>
 #include <asm/uaccess.h>
 #endif

 #include "videocodec.h"

 static int debug = 0;
 module_param(debug, int, 0);
 MODULE_PARM_DESC(debug, "Debug level (0-4)");

 #define dprintk(num, format, args...) \
 	do { \
 		if (debug >= num) \
 			printk(format, ##args); \
 	} while (0)

 struct attached_list {
 	struct videocodec *codec;
 	struct attached_list *next;
 };

 struct codec_list {
 	const struct videocodec *codec;
 	int attached;
 	struct attached_list *list;
 	struct codec_list *next;
 };

 static struct codec_list *codeclist_top = NULL;

 /* ================================================= */
 /* function prototypes of the master/slave interface */
 /* ================================================= */

 struct videocodec *
 videocodec_attach (struct videocodec_master *master)
 {
 	struct codec_list *h = codeclist_top;
 	struct attached_list *a, *ptr;
 	struct videocodec *codec;
 	int res;

 	if (!master) {
 		dprintk(1, KERN_ERR "videocodec_attach: no data\n");
 		return NULL;
 	}

 	dprintk(2,
 		"videocodec_attach: '%s', type: %x, flags %lx, magic %lx\n",
 		master->name, master->type, master->flags, master->magic);

 	if (!h) {
 		dprintk(1,
 			KERN_ERR
 			"videocodec_attach: no device available\n");
 		return NULL;
 	}

 	while (h) {
 		// attach only if the slave has at least the flags
 		// expected by the master
 		if ((master->flags & h->codec->flags) == master->flags) {
 			dprintk(4, "videocodec_attach: try '%s'\n",
 				h->codec->name);

 			if (!try_module_get(h->codec->owner))
 				return NULL;

 			codec =
 			    kmalloc(sizeof(struct videocodec), GFP_KERNEL);
 			if (!codec) {
 				dprintk(1,
 					KERN_ERR
 					"videocodec_attach: no mem\n");
 				goto out_module_put;
 			}
 			memcpy(codec, h->codec, sizeof(struct videocodec));

 			snprintf(codec->name, sizeof(codec->name),
 				 "%s[%d]", codec->name, h->attached);
 			codec->master_data = master;
 			res = codec->setup(codec);
 			if (res == 0) {
 				dprintk(3, "videocodec_attach '%s'\n",
 					codec->name);
 				ptr = (struct attached_list *)
 				    kmalloc(sizeof(struct attached_list),
 					    GFP_KERNEL);
 				if (!ptr) {
 					dprintk(1,
 						KERN_ERR
 						"videocodec_attach: no memory\n");
 					goto out_kfree;
 				}
 				memset(ptr, 0,
 				       sizeof(struct attached_list));
 				ptr->codec = codec;

 				a = h->list;
 				if (!a) {
 					h->list = ptr;
 					dprintk(4,
 						"videocodec: first element\n");
 				} else {
 					while (a->next)
 						a = a->next;	// find end
 					a->next = ptr;
 					dprintk(4,
 						"videocodec: in after '%s'\n",
 						h->codec->name);
 				}

 				h->attached += 1;
 				return codec;
 			} else {
 				kfree(codec);
 			}
 		}
 		h = h->next;
 	}

 	dprintk(1, KERN_ERR "videocodec_attach: no codec found!\n");
 	return NULL;

  out_module_put:
 	module_put(h->codec->owner);
  out_kfree:
 	kfree(codec);
 	return NULL;
 }

 int
 videocodec_detach (struct videocodec *codec)
 {
 	struct codec_list *h = codeclist_top;
 	struct attached_list *a, *prev;
 	int res;

 	if (!codec) {
 		dprintk(1, KERN_ERR "videocodec_detach: no data\n");
 		return -EINVAL;
 	}

 	dprintk(2,
 		"videocodec_detach: '%s', type: %x, flags %lx, magic %lx\n",
 		codec->name, codec->type, codec->flags, codec->magic);

 	if (!h) {
 		dprintk(1,
 			KERN_ERR "videocodec_detach: no device left...\n");
 		return -ENXIO;
 	}

 	while (h) {
 		a = h->list;
 		prev = NULL;
 		while (a) {
 			if (codec == a->codec) {
 				res = a->codec->unset(a->codec);
 				if (res >= 0) {
 					dprintk(3,
 						"videocodec_detach: '%s'\n",
 						a->codec->name);
 					a->codec->master_data = NULL;
 				} else {
 					dprintk(1,
 						KERN_ERR
 						"videocodec_detach: '%s'\n",
 						a->codec->name);
 					a->codec->master_data = NULL;
 				}
 				if (prev == NULL) {
 					h->list = a->next;
 					dprintk(4,
 						"videocodec: delete first\n");
 				} else {
 					prev->next = a->next;
 					dprintk(4,
 						"videocodec: delete middle\n");
 				}
 				module_put(a->codec->owner);
 				kfree(a->codec);
 				kfree(a);
 				h->attached -= 1;
 				return 0;
 			}
 			prev = a;
 			a = a->next;
 		}
 		h = h->next;
 	}

 	dprintk(1, KERN_ERR "videocodec_detach: given codec not found!\n");
 	return -EINVAL;
 }

 int
 videocodec_register (const struct videocodec *codec)
 {
 	struct codec_list *ptr, *h = codeclist_top;

 	if (!codec) {
 		dprintk(1, KERN_ERR "videocodec_register: no data!\n");
 		return -EINVAL;
 	}

 	dprintk(2,
 		"videocodec: register '%s', type: %x, flags %lx, magic %lx\n",
 		codec->name, codec->type, codec->flags, codec->magic);

 	ptr =
 	    (struct codec_list *) kmalloc(sizeof(struct codec_list),
 					  GFP_KERNEL);
 	if (!ptr) {
 		dprintk(1, KERN_ERR "videocodec_register: no memory\n");
 		return -ENOMEM;
 	}
 	memset(ptr, 0, sizeof(struct codec_list));
 	ptr->codec = codec;

 	if (!h) {
 		codeclist_top = ptr;
 		dprintk(4, "videocodec: hooked in as first element\n");
 	} else {
 		while (h->next)
 			h = h->next;	// find the end
 		h->next = ptr;
 		dprintk(4, "videocodec: hooked in after '%s'\n",
 			h->codec->name);
 	}

 	return 0;
 }

 int
 videocodec_unregister (const struct videocodec *codec)
 {
 	struct codec_list *prev = NULL, *h = codeclist_top;

 	if (!codec) {
 		dprintk(1, KERN_ERR "videocodec_unregister: no data!\n");
 		return -EINVAL;
 	}

 	dprintk(2,
 		"videocodec: unregister '%s', type: %x, flags %lx, magic %lx\n",
 		codec->name, codec->type, codec->flags, codec->magic);

 	if (!h) {
 		dprintk(1,
 			KERN_ERR
 			"videocodec_unregister: no device left...\n");
 		return -ENXIO;
 	}

 	while (h) {
 		if (codec == h->codec) {
 			if (h->attached) {
 				dprintk(1,
 					KERN_ERR
 					"videocodec: '%s' is used\n",
 					h->codec->name);
 				return -EBUSY;
 			}
 			dprintk(3, "videocodec: unregister '%s' is ok.\n",
 				h->codec->name);
 			if (prev == NULL) {
 				codeclist_top = h->next;
 				dprintk(4,
 					"videocodec: delete first element\n");
 			} else {
 				prev->next = h->next;
 				dprintk(4,
 					"videocodec: delete middle element\n");
 			}
 			kfree(h);
 			return 0;
 		}
 		prev = h;
 		h = h->next;
 	}

 	dprintk(1,
 		KERN_ERR
 		"videocodec_unregister: given codec not found!\n");
 	return -EINVAL;
 }

 #ifdef CONFIG_PROC_FS
 /* ============ */
 /* procfs stuff */
 /* ============ */

 static char *videocodec_buf = NULL;
 static int videocodec_bufsize = 0;

 static int
 videocodec_build_table (void)
 {
 	struct codec_list *h = codeclist_top;
 	struct attached_list *a;
 	int i = 0, size;

 	// sum up amount of slaves plus their attached masters
 	while (h) {
 		i += h->attached + 1;
 		h = h->next;
 	}
 #define LINESIZE 100
 	size = LINESIZE * (i + 1);

 	dprintk(3, "videocodec_build table: %d entries, %d bytes\n", i,
 		size);

 	kfree(videocodec_buf);
 	videocodec_buf = (char *) kmalloc(size, GFP_KERNEL);

 	i = 0;
 	i += scnprintf(videocodec_buf + i, size - 1,
 		      "<S>lave or attached <M>aster name  type flags    magic    ");
 	i += scnprintf(videocodec_buf + i, size -i - 1, "(connected as)\n");

 	h = codeclist_top;
 	while (h) {
 		if (i > (size - LINESIZE))
 			break;	// security check
 		i += scnprintf(videocodec_buf + i, size -i -1,
 			      "S %32s %04x %08lx %08lx (TEMPLATE)\n",
 			      h->codec->name, h->codec->type,
 			      h->codec->flags, h->codec->magic);
 		a = h->list;
 		while (a) {
 			if (i > (size - LINESIZE))
 				break;	// security check
 			i += scnprintf(videocodec_buf + i, size -i -1,
 				      "M %32s %04x %08lx %08lx (%s)\n",
 				      a->codec->master_data->name,
 				      a->codec->master_data->type,
 				      a->codec->master_data->flags,
 				      a->codec->master_data->magic,
 				      a->codec->name);
 			a = a->next;
 		}
 		h = h->next;
 	}

 	return i;
 }

 //The definition:
 //typedef int (read_proc_t)(char *page, char **start, off_t off,
 //                          int count, int *eof, void *data);

 static int
 videocodec_info (char  *buffer,
 		 char **buffer_location,
 		 off_t  offset,
 		 int    buffer_length,
 		 int   *eof,
 		 void  *data)
 {
 	int size;

 	dprintk(3, "videocodec_info: offset: %ld, len %d / size %d\n",
 		offset, buffer_length, videocodec_bufsize);

 	if (offset == 0) {
 		videocodec_bufsize = videocodec_build_table();
 	}
 	if ((offset < 0) || (offset >= videocodec_bufsize)) {
 		dprintk(4,
 			"videocodec_info: call delivers no result, return 0\n");
 		*eof = 1;
 		return 0;
 	}

 	if (buffer_length < (videocodec_bufsize - offset)) {
 		dprintk(4, "videocodec_info: %ld needed, %d got\n",
 			videocodec_bufsize - offset, buffer_length);
 		size = buffer_length;
 	} else {
 		dprintk(4, "videocodec_info: last reading of %ld bytes\n",
 			videocodec_bufsize - offset);
 		size = videocodec_bufsize - offset;
 		*eof = 1;
 	}

 	memcpy(buffer, videocodec_buf + offset, size);
 	/* doesn't work...                           */
 	/* copy_to_user(buffer, videocodec_buf+offset, size); */
 	/* *buffer_location = videocodec_buf+offset; */

 	return size;
 }
 #endif

 /* ===================== */
 /* hook in driver module */
 /* ===================== */
 static int __init
 videocodec_init (void)
 {
 #ifdef CONFIG_PROC_FS
 	static struct proc_dir_entry *videocodec_proc_entry;
 #endif

 	printk(KERN_INFO "Linux video codec intermediate layer: %s\n",
 	       VIDEOCODEC_VERSION);

 #ifdef CONFIG_PROC_FS
 	videocodec_buf = NULL;
 	videocodec_bufsize = 0;

 	videocodec_proc_entry = create_proc_entry("videocodecs", 0, NULL);
 	if (videocodec_proc_entry) {
 		videocodec_proc_entry->read_proc = videocodec_info;
 		videocodec_proc_entry->write_proc = NULL;
 		videocodec_proc_entry->data = NULL;
 		videocodec_proc_entry->owner = THIS_MODULE;
 	} else {
 		dprintk(1, KERN_ERR "videocodec: can't init procfs.\n");
 	}
 #endif
 	return 0;
 }

 static void __exit
 videocodec_exit (void)
 {
 #ifdef CONFIG_PROC_FS
 	remove_proc_entry("videocodecs", NULL);
 	kfree(videocodec_buf);
 #endif
 }

 EXPORT_SYMBOL(videocodec_attach);
 EXPORT_SYMBOL(videocodec_detach);
 EXPORT_SYMBOL(videocodec_register);
 EXPORT_SYMBOL(videocodec_unregister);

 module_init(videocodec_init);
 module_exit(videocodec_exit);

 MODULE_AUTHOR("Wolfgang Scherr <scherr@net4you.at>");
 MODULE_DESCRIPTION("Intermediate API module for video codecs "
 		   VIDEOCODEC_VERSION);
 MODULE_LICENSE("GPL");
	/*
	* VIDEO MOTION CODECs internal API for video devices
	*
	* Interface for MJPEG (and maybe later MPEG/WAVELETS) codec's
	* bound to a master device.
	*
	* (c) 2002 Wolfgang Scherr <scherr@net4you.at>
	*
	* $Id: videocodec.c,v 1.1.2.8 2003/03/29 07:16:04 rbultje Exp $
	*
	* ------------------------------------------------------------------------
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 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 General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	*
	* ------------------------------------------------------------------------
	*/

	#define VIDEOCODEC_VERSION "v0.2"

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/types.h>
	#include <linux/slab.h>

	// kernel config is here (procfs flag)
	#include <linux/config.h>

	#ifdef CONFIG_PROC_FS
	#include <linux/proc_fs.h>
	#include <asm/uaccess.h>
	#endif

	#include "videocodec.h"

	static int debug = 0;
	module_param(debug, int, 0);
	MODULE_PARM_DESC(debug, "Debug level (0-4)");

	#define dprintk(num, format, args...) \
	do { \
	if (debug >= num) \
	printk(format, ##args); \
	} while (0)

	struct attached_list {
	struct videocodec *codec;
	struct attached_list *next;
	};

	struct codec_list {
	const struct videocodec *codec;
	int attached;
	struct attached_list *list;
	struct codec_list *next;
	};

	static struct codec_list *codeclist_top = NULL;

	/* ================================================= */
	/* function prototypes of the master/slave interface */
	/* ================================================= */

	struct videocodec *
	videocodec_attach (struct videocodec_master *master)
	{
	struct codec_list *h = codeclist_top;
	struct attached_list a, ptr;
	struct videocodec *codec;
	int res;

	if (!master) {
	dprintk(1, KERN_ERR "videocodec_attach: no data\n");
	return NULL;
	}

	dprintk(2,
	"videocodec_attach: '%s', type: %x, flags %lx, magic %lx\n",
	master->name, master->type, master->flags, master->magic);

	if (!h) {
	dprintk(1,
	KERN_ERR
	"videocodec_attach: no device available\n");
	return NULL;
	}

	while (h) {
	// attach only if the slave has at least the flags
	// expected by the master
	if ((master->flags & h->codec->flags) == master->flags) {
	dprintk(4, "videocodec_attach: try '%s'\n",
	h->codec->name);

	if (!try_module_get(h->codec->owner))
	return NULL;

	codec =
	kmalloc(sizeof(struct videocodec), GFP_KERNEL);
	if (!codec) {
	dprintk(1,
	KERN_ERR
	"videocodec_attach: no mem\n");
	goto out_module_put;
	}
	memcpy(codec, h->codec, sizeof(struct videocodec));

	snprintf(codec->name, sizeof(codec->name),
	"%s[%d]", codec->name, h->attached);
	codec->master_data = master;
	res = codec->setup(codec);
	if (res == 0) {
	dprintk(3, "videocodec_attach '%s'\n",
	codec->name);
	ptr = (struct attached_list *)
	kmalloc(sizeof(struct attached_list),
	GFP_KERNEL);
	if (!ptr) {
	dprintk(1,
	KERN_ERR
	"videocodec_attach: no memory\n");
	goto out_kfree;
	}
	memset(ptr, 0,
	sizeof(struct attached_list));
	ptr->codec = codec;

	a = h->list;
	if (!a) {
	h->list = ptr;
	dprintk(4,
	"videocodec: first element\n");
	} else {
	while (a->next)
	a = a->next; // find end
	a->next = ptr;
	dprintk(4,
	"videocodec: in after '%s'\n",
	h->codec->name);
	}

	h->attached += 1;
	return codec;
	} else {
	kfree(codec);
	}
	}
	h = h->next;
	}

	dprintk(1, KERN_ERR "videocodec_attach: no codec found!\n");
	return NULL;

	out_module_put:
	module_put(h->codec->owner);
	out_kfree:
	kfree(codec);
	return NULL;
	}

	int
	videocodec_detach (struct videocodec *codec)
	{
	struct codec_list *h = codeclist_top;
	struct attached_list a, prev;
	int res;

	if (!codec) {
	dprintk(1, KERN_ERR "videocodec_detach: no data\n");
	return -EINVAL;
	}

	dprintk(2,
	"videocodec_detach: '%s', type: %x, flags %lx, magic %lx\n",
	codec->name, codec->type, codec->flags, codec->magic);

	if (!h) {
	dprintk(1,
	KERN_ERR "videocodec_detach: no device left...\n");
	return -ENXIO;
	}

	while (h) {
	a = h->list;
	prev = NULL;
	while (a) {
	if (codec == a->codec) {
	res = a->codec->unset(a->codec);
	if (res >= 0) {
	dprintk(3,
	"videocodec_detach: '%s'\n",
	a->codec->name);
	a->codec->master_data = NULL;
	} else {
	dprintk(1,
	KERN_ERR
	"videocodec_detach: '%s'\n",
	a->codec->name);
	a->codec->master_data = NULL;
	}
	if (prev == NULL) {
	h->list = a->next;
	dprintk(4,
	"videocodec: delete first\n");
	} else {
	prev->next = a->next;
	dprintk(4,
	"videocodec: delete middle\n");
	}
	module_put(a->codec->owner);
	kfree(a->codec);
	kfree(a);
	h->attached -= 1;
	return 0;
	}
	prev = a;
	a = a->next;
	}
	h = h->next;
	}

	dprintk(1, KERN_ERR "videocodec_detach: given codec not found!\n");
	return -EINVAL;
	}

	int
	videocodec_register (const struct videocodec *codec)
	{
	struct codec_list ptr, h = codeclist_top;

	if (!codec) {
	dprintk(1, KERN_ERR "videocodec_register: no data!\n");
	return -EINVAL;
	}

	dprintk(2,
	"videocodec: register '%s', type: %x, flags %lx, magic %lx\n",
	codec->name, codec->type, codec->flags, codec->magic);

	ptr =
	(struct codec_list *) kmalloc(sizeof(struct codec_list),
	GFP_KERNEL);
	if (!ptr) {
	dprintk(1, KERN_ERR "videocodec_register: no memory\n");
	return -ENOMEM;
	}
	memset(ptr, 0, sizeof(struct codec_list));
	ptr->codec = codec;

	if (!h) {
	codeclist_top = ptr;
	dprintk(4, "videocodec: hooked in as first element\n");
	} else {
	while (h->next)
	h = h->next; // find the end
	h->next = ptr;
	dprintk(4, "videocodec: hooked in after '%s'\n",
	h->codec->name);
	}

	return 0;
	}

	int
	videocodec_unregister (const struct videocodec *codec)
	{
	struct codec_list prev = NULL, h = codeclist_top;

	if (!codec) {
	dprintk(1, KERN_ERR "videocodec_unregister: no data!\n");
	return -EINVAL;
	}

	dprintk(2,
	"videocodec: unregister '%s', type: %x, flags %lx, magic %lx\n",
	codec->name, codec->type, codec->flags, codec->magic);

	if (!h) {
	dprintk(1,
	KERN_ERR
	"videocodec_unregister: no device left...\n");
	return -ENXIO;
	}

	while (h) {
	if (codec == h->codec) {
	if (h->attached) {
	dprintk(1,
	KERN_ERR
	"videocodec: '%s' is used\n",
	h->codec->name);
	return -EBUSY;
	}
	dprintk(3, "videocodec: unregister '%s' is ok.\n",
	h->codec->name);
	if (prev == NULL) {
	codeclist_top = h->next;
	dprintk(4,
	"videocodec: delete first element\n");
	} else {
	prev->next = h->next;
	dprintk(4,
	"videocodec: delete middle element\n");
	}
	kfree(h);
	return 0;
	}
	prev = h;
	h = h->next;
	}

	dprintk(1,
	KERN_ERR
	"videocodec_unregister: given codec not found!\n");
	return -EINVAL;
	}

	#ifdef CONFIG_PROC_FS
	/* ============ */
	/* procfs stuff */
	/* ============ */

	static char *videocodec_buf = NULL;
	static int videocodec_bufsize = 0;

	static int
	videocodec_build_table (void)
	{
	struct codec_list *h = codeclist_top;
	struct attached_list *a;
	int i = 0, size;

	// sum up amount of slaves plus their attached masters
	while (h) {
	i += h->attached + 1;
	h = h->next;
	}
	#define LINESIZE 100
	size = LINESIZE * (i + 1);

	dprintk(3, "videocodec_build table: %d entries, %d bytes\n", i,
	size);

	kfree(videocodec_buf);
	videocodec_buf = (char *) kmalloc(size, GFP_KERNEL);

	i = 0;
	i += scnprintf(videocodec_buf + i, size - 1,
	"<S>lave or attached <M>aster name type flags magic ");
	i += scnprintf(videocodec_buf + i, size -i - 1, "(connected as)\n");

	h = codeclist_top;
	while (h) {
	if (i > (size - LINESIZE))
	break; // security check
	i += scnprintf(videocodec_buf + i, size -i -1,
	"S %32s %04x %08lx %08lx (TEMPLATE)\n",
	h->codec->name, h->codec->type,
	h->codec->flags, h->codec->magic);
	a = h->list;
	while (a) {
	if (i > (size - LINESIZE))
	break; // security check
	i += scnprintf(videocodec_buf + i, size -i -1,
	"M %32s %04x %08lx %08lx (%s)\n",
	a->codec->master_data->name,
	a->codec->master_data->type,
	a->codec->master_data->flags,
	a->codec->master_data->magic,
	a->codec->name);
	a = a->next;
	}
	h = h->next;
	}

	return i;
	}

	//The definition:
	//typedef int (read_proc_t)(char page, char *start, off_t off,
	// int count, int eof, void data);

	static int
	videocodec_info (char *buffer,
	char **buffer_location,
	off_t offset,
	int buffer_length,
	int *eof,
	void *data)
	{
	int size;

	dprintk(3, "videocodec_info: offset: %ld, len %d / size %d\n",
	offset, buffer_length, videocodec_bufsize);

	if (offset == 0) {
	videocodec_bufsize = videocodec_build_table();
	}
	if ((offset < 0) \|\| (offset >= videocodec_bufsize)) {
	dprintk(4,
	"videocodec_info: call delivers no result, return 0\n");
	*eof = 1;
	return 0;
	}

	if (buffer_length < (videocodec_bufsize - offset)) {
	dprintk(4, "videocodec_info: %ld needed, %d got\n",
	videocodec_bufsize - offset, buffer_length);
	size = buffer_length;
	} else {
	dprintk(4, "videocodec_info: last reading of %ld bytes\n",
	videocodec_bufsize - offset);
	size = videocodec_bufsize - offset;
	*eof = 1;
	}

	memcpy(buffer, videocodec_buf + offset, size);
	/* doesn't work... */
	/* copy_to_user(buffer, videocodec_buf+offset, size); */
	/* buffer_location = videocodec_buf+offset; /

	return size;
	}
	#endif

	/* ===================== */
	/* hook in driver module */
	/* ===================== */
	static int __init
	videocodec_init (void)
	{
	#ifdef CONFIG_PROC_FS
	static struct proc_dir_entry *videocodec_proc_entry;
	#endif

	printk(KERN_INFO "Linux video codec intermediate layer: %s\n",
	VIDEOCODEC_VERSION);

	#ifdef CONFIG_PROC_FS
	videocodec_buf = NULL;
	videocodec_bufsize = 0;

	videocodec_proc_entry = create_proc_entry("videocodecs", 0, NULL);
	if (videocodec_proc_entry) {
	videocodec_proc_entry->read_proc = videocodec_info;
	videocodec_proc_entry->write_proc = NULL;
	videocodec_proc_entry->data = NULL;
	videocodec_proc_entry->owner = THIS_MODULE;
	} else {
	dprintk(1, KERN_ERR "videocodec: can't init procfs.\n");
	}
	#endif
	return 0;
	}

	static void __exit
	videocodec_exit (void)
	{
	#ifdef CONFIG_PROC_FS
	remove_proc_entry("videocodecs", NULL);
	kfree(videocodec_buf);
	#endif
	}

	EXPORT_SYMBOL(videocodec_attach);
	EXPORT_SYMBOL(videocodec_detach);
	EXPORT_SYMBOL(videocodec_register);
	EXPORT_SYMBOL(videocodec_unregister);

	module_init(videocodec_init);
	module_exit(videocodec_exit);

	MODULE_AUTHOR("Wolfgang Scherr <scherr@net4you.at>");
	MODULE_DESCRIPTION("Intermediate API module for video codecs "
	VIDEOCODEC_VERSION);
	MODULE_LICENSE("GPL");