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Commit ea082fb1 authored by H Hartley Sweeten's avatar H Hartley Sweeten Committed by Greg Kroah-Hartman
Browse files

staging: comedi: separate out comedi_buf_* functions 



Create a new file, comedi_buf.c, to hold all the comedi_async buffer
functions. Currently they are all in drivers.c and really don't have
any association with that source file.

Signed-off-by: default avatarH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d1843132

drivers/staging/comedi/Makefile

+2 −1
Original line number Diff line number Diff line 
comedi-y			:= comedi_fops.o range.o drivers.o

comedi-y			:= comedi_fops.o range.o drivers.o \

				   comedi_buf.o

comedi-$(CONFIG_PROC_FS)	+= proc.o

comedi-$(CONFIG_COMPAT)		+= comedi_compat32.o

drivers/staging/comedi/comedi_buf.c

0 → 100644
+421 −0
Original line number Diff line number Diff line 
/*

 * comedi_buf.c

 *

 * COMEDI - Linux Control and Measurement Device Interface

 * Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org>

 *

 * 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.

 */



#include "comedidev.h"

#include "comedi_internal.h"



int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,

		     unsigned long new_size)

{

	struct comedi_async *async = s->async;



	/* Round up new_size to multiple of PAGE_SIZE */

	new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;



	/* if no change is required, do nothing */

	if (async->prealloc_buf && async->prealloc_bufsz == new_size)

		return 0;



	/*  deallocate old buffer */

	if (async->prealloc_buf) {

		vunmap(async->prealloc_buf);

		async->prealloc_buf = NULL;

		async->prealloc_bufsz = 0;

	}

	if (async->buf_page_list) {

		unsigned i;

		for (i = 0; i < async->n_buf_pages; ++i) {

			if (async->buf_page_list[i].virt_addr) {

				clear_bit(PG_reserved,

					&(virt_to_page(async->buf_page_list[i].

							virt_addr)->flags));

				if (s->async_dma_dir != DMA_NONE) {

					dma_free_coherent(dev->hw_dev,

							  PAGE_SIZE,

							  async->

							  buf_page_list

							  [i].virt_addr,

							  async->

							  buf_page_list

							  [i].dma_addr);

				} else {

					free_page((unsigned long)

						  async->buf_page_list[i].

						  virt_addr);

				}

			}

		}

		vfree(async->buf_page_list);

		async->buf_page_list = NULL;

		async->n_buf_pages = 0;

	}

	/*  allocate new buffer */

	if (new_size) {

		unsigned i = 0;

		unsigned n_pages = new_size >> PAGE_SHIFT;

		struct page **pages = NULL;



		async->buf_page_list =

		    vzalloc(sizeof(struct comedi_buf_page) * n_pages);

		if (async->buf_page_list)

			pages = vmalloc(sizeof(struct page *) * n_pages);



		if (pages) {

			for (i = 0; i < n_pages; i++) {

				if (s->async_dma_dir != DMA_NONE) {

					async->buf_page_list[i].virt_addr =

					    dma_alloc_coherent(dev->hw_dev,

							       PAGE_SIZE,

							       &async->

							       buf_page_list

							       [i].dma_addr,

							       GFP_KERNEL |

							       __GFP_COMP);

				} else {

					async->buf_page_list[i].virt_addr =

					    (void *)

					    get_zeroed_page(GFP_KERNEL);

				}

				if (async->buf_page_list[i].virt_addr == NULL)

					break;



				set_bit(PG_reserved,

					&(virt_to_page(async->buf_page_list[i].

							virt_addr)->flags));

				pages[i] = virt_to_page(async->buf_page_list[i].

								virt_addr);

			}

		}

		if (i == n_pages) {

			async->prealloc_buf =

#ifdef PAGE_KERNEL_NOCACHE

			    vmap(pages, n_pages, VM_MAP, PAGE_KERNEL_NOCACHE);

#else

			    vmap(pages, n_pages, VM_MAP, PAGE_KERNEL);

#endif

		}

		vfree(pages);



		if (async->prealloc_buf == NULL) {

			/* Some allocation failed above. */

			if (async->buf_page_list) {

				for (i = 0; i < n_pages; i++) {

					if (async->buf_page_list[i].virt_addr ==

					    NULL) {

						break;

					}

					clear_bit(PG_reserved,

						&(virt_to_page(async->

							buf_page_list[i].

							virt_addr)->flags));

					if (s->async_dma_dir != DMA_NONE) {

						dma_free_coherent(dev->hw_dev,

								  PAGE_SIZE,

								  async->

								  buf_page_list

								  [i].virt_addr,

								  async->

								  buf_page_list

								  [i].dma_addr);

					} else {

						free_page((unsigned long)

							  async->buf_page_list

							  [i].virt_addr);

					}

				}

				vfree(async->buf_page_list);

				async->buf_page_list = NULL;

			}

			return -ENOMEM;

		}

		async->n_buf_pages = n_pages;

	}

	async->prealloc_bufsz = new_size;



	return 0;

}



void comedi_reset_async_buf(struct comedi_async *async)

{

	async->buf_write_alloc_count = 0;

	async->buf_write_count = 0;

	async->buf_read_alloc_count = 0;

	async->buf_read_count = 0;



	async->buf_write_ptr = 0;

	async->buf_read_ptr = 0;



	async->cur_chan = 0;

	async->scan_progress = 0;

	async->munge_chan = 0;

	async->munge_count = 0;

	async->munge_ptr = 0;



	async->events = 0;

}



unsigned int comedi_buf_write_n_available(struct comedi_async *async)

{

	unsigned int free_end;

	unsigned int nbytes;



	if (async == NULL)

		return 0;



	free_end = async->buf_read_count + async->prealloc_bufsz;

	nbytes = free_end - async->buf_write_alloc_count;

	nbytes -= nbytes % bytes_per_sample(async->subdevice);

	/* barrier insures the read of buf_read_count in this

	   query occurs before any following writes to the buffer which

	   might be based on the return value from this query.

	 */

	smp_mb();

	return nbytes;

}



/* allocates chunk for the writer from free buffer space */

unsigned int comedi_buf_write_alloc(struct comedi_async *async,

				    unsigned int nbytes)

{

	unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;



	if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0)

		nbytes = free_end - async->buf_write_alloc_count;



	async->buf_write_alloc_count += nbytes;

	/* barrier insures the read of buf_read_count above occurs before

	   we write data to the write-alloc'ed buffer space */

	smp_mb();

	return nbytes;

}

EXPORT_SYMBOL(comedi_buf_write_alloc);



/* allocates nothing unless it can completely fulfill the request */

unsigned int comedi_buf_write_alloc_strict(struct comedi_async *async,

					   unsigned int nbytes)

{

	unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;



	if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0)

		nbytes = 0;



	async->buf_write_alloc_count += nbytes;

	/* barrier insures the read of buf_read_count above occurs before

	   we write data to the write-alloc'ed buffer space */

	smp_mb();

	return nbytes;

}



/* munging is applied to data by core as it passes between user

 * and kernel space */

static unsigned int comedi_buf_munge(struct comedi_async *async,

				     unsigned int num_bytes)

{

	struct comedi_subdevice *s = async->subdevice;

	unsigned int count = 0;

	const unsigned num_sample_bytes = bytes_per_sample(s);



	if (s->munge == NULL || (async->cmd.flags & CMDF_RAWDATA)) {

		async->munge_count += num_bytes;

		BUG_ON((int)(async->munge_count - async->buf_write_count) > 0);

		return num_bytes;

	}

	/* don't munge partial samples */

	num_bytes -= num_bytes % num_sample_bytes;

	while (count < num_bytes) {

		int block_size;



		block_size = num_bytes - count;

		if (block_size < 0) {

			dev_warn(s->device->class_dev,

				 "%s: %s: bug! block_size is negative\n",

				 __FILE__, __func__);

			break;

		}

		if ((int)(async->munge_ptr + block_size -

			  async->prealloc_bufsz) > 0)

			block_size = async->prealloc_bufsz - async->munge_ptr;



		s->munge(s->device, s, async->prealloc_buf + async->munge_ptr,

			 block_size, async->munge_chan);



		smp_wmb();	/* barrier insures data is munged in buffer

				 * before munge_count is incremented */



		async->munge_chan += block_size / num_sample_bytes;

		async->munge_chan %= async->cmd.chanlist_len;

		async->munge_count += block_size;

		async->munge_ptr += block_size;

		async->munge_ptr %= async->prealloc_bufsz;

		count += block_size;

	}

	BUG_ON((int)(async->munge_count - async->buf_write_count) > 0);

	return count;

}



/* transfers a chunk from writer to filled buffer space */

unsigned comedi_buf_write_free(struct comedi_async *async, unsigned int nbytes)

{

	if ((int)(async->buf_write_count + nbytes -

		  async->buf_write_alloc_count) > 0) {

		dev_info(async->subdevice->device->class_dev,

			 "attempted to write-free more bytes than have been write-allocated.\n");

		nbytes = async->buf_write_alloc_count - async->buf_write_count;

	}

	async->buf_write_count += nbytes;

	async->buf_write_ptr += nbytes;

	comedi_buf_munge(async, async->buf_write_count - async->munge_count);

	if (async->buf_write_ptr >= async->prealloc_bufsz)

		async->buf_write_ptr %= async->prealloc_bufsz;



	return nbytes;

}

EXPORT_SYMBOL(comedi_buf_write_free);



unsigned int comedi_buf_read_n_available(struct comedi_async *async)

{

	unsigned num_bytes;



	if (async == NULL)

		return 0;

	num_bytes = async->munge_count - async->buf_read_count;

	/* barrier insures the read of munge_count in this

	   query occurs before any following reads of the buffer which

	   might be based on the return value from this query.

	 */

	smp_rmb();

	return num_bytes;

}

EXPORT_SYMBOL(comedi_buf_read_n_available);



/* allocates a chunk for the reader from filled (and munged) buffer space */

unsigned comedi_buf_read_alloc(struct comedi_async *async, unsigned nbytes)

{

	if ((int)(async->buf_read_alloc_count + nbytes - async->munge_count) >

	    0) {

		nbytes = async->munge_count - async->buf_read_alloc_count;

	}

	async->buf_read_alloc_count += nbytes;

	/* barrier insures read of munge_count occurs before we actually read

	   data out of buffer */

	smp_rmb();

	return nbytes;

}

EXPORT_SYMBOL(comedi_buf_read_alloc);



/* transfers control of a chunk from reader to free buffer space */

unsigned comedi_buf_read_free(struct comedi_async *async, unsigned int nbytes)

{

	/* barrier insures data has been read out of

	 * buffer before read count is incremented */

	smp_mb();

	if ((int)(async->buf_read_count + nbytes -

		  async->buf_read_alloc_count) > 0) {

		dev_info(async->subdevice->device->class_dev,

			 "attempted to read-free more bytes than have been read-allocated.\n");

		nbytes = async->buf_read_alloc_count - async->buf_read_count;

	}

	async->buf_read_count += nbytes;

	async->buf_read_ptr += nbytes;

	async->buf_read_ptr %= async->prealloc_bufsz;

	return nbytes;

}

EXPORT_SYMBOL(comedi_buf_read_free);



int comedi_buf_put(struct comedi_async *async, short x)

{

	unsigned int n = comedi_buf_write_alloc_strict(async, sizeof(short));



	if (n < sizeof(short)) {

		async->events |= COMEDI_CB_ERROR;

		return 0;

	}

	*(short *)(async->prealloc_buf + async->buf_write_ptr) = x;

	comedi_buf_write_free(async, sizeof(short));

	return 1;

}

EXPORT_SYMBOL(comedi_buf_put);



int comedi_buf_get(struct comedi_async *async, short *x)

{

	unsigned int n = comedi_buf_read_n_available(async);



	if (n < sizeof(short))

		return 0;

	comedi_buf_read_alloc(async, sizeof(short));

	*x = *(short *)(async->prealloc_buf + async->buf_read_ptr);

	comedi_buf_read_free(async, sizeof(short));

	return 1;

}

EXPORT_SYMBOL(comedi_buf_get);



void comedi_buf_memcpy_to(struct comedi_async *async, unsigned int offset,

			  const void *data, unsigned int num_bytes)

{

	unsigned int write_ptr = async->buf_write_ptr + offset;



	if (write_ptr >= async->prealloc_bufsz)

		write_ptr %= async->prealloc_bufsz;



	while (num_bytes) {

		unsigned int block_size;



		if (write_ptr + num_bytes > async->prealloc_bufsz)

			block_size = async->prealloc_bufsz - write_ptr;

		else

			block_size = num_bytes;



		memcpy(async->prealloc_buf + write_ptr, data, block_size);



		data += block_size;

		num_bytes -= block_size;



		write_ptr = 0;

	}

}

EXPORT_SYMBOL(comedi_buf_memcpy_to);



void comedi_buf_memcpy_from(struct comedi_async *async, unsigned int offset,

			    void *dest, unsigned int nbytes)

{

	void *src;

	unsigned int read_ptr = async->buf_read_ptr + offset;



	if (read_ptr >= async->prealloc_bufsz)

		read_ptr %= async->prealloc_bufsz;



	while (nbytes) {

		unsigned int block_size;



		src = async->prealloc_buf + read_ptr;



		if (nbytes >= async->prealloc_bufsz - read_ptr)

			block_size = async->prealloc_bufsz - read_ptr;

		else

			block_size = nbytes;



		memcpy(dest, src, block_size);

		nbytes -= block_size;

		dest += block_size;

		read_ptr = 0;

	}

}

EXPORT_SYMBOL(comedi_buf_memcpy_from);

drivers/staging/comedi/drivers.c

+0 −398
Original line number Diff line number Diff line
@@ -430,404 +430,6 @@ static int insn_rw_emulate_bits(struct comedi_device *dev, 
	return 1;

}



int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,

		     unsigned long new_size)

{

	struct comedi_async *async = s->async;



	/* Round up new_size to multiple of PAGE_SIZE */

	new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;



	/* if no change is required, do nothing */

	if (async->prealloc_buf && async->prealloc_bufsz == new_size)

		return 0;



	/*  deallocate old buffer */

	if (async->prealloc_buf) {

		vunmap(async->prealloc_buf);

		async->prealloc_buf = NULL;

		async->prealloc_bufsz = 0;

	}

	if (async->buf_page_list) {

		unsigned i;

		for (i = 0; i < async->n_buf_pages; ++i) {

			if (async->buf_page_list[i].virt_addr) {

				clear_bit(PG_reserved,

					&(virt_to_page(async->buf_page_list[i].

							virt_addr)->flags));

				if (s->async_dma_dir != DMA_NONE) {

					dma_free_coherent(dev->hw_dev,

							  PAGE_SIZE,

							  async->

							  buf_page_list

							  [i].virt_addr,

							  async->

							  buf_page_list

							  [i].dma_addr);

				} else {

					free_page((unsigned long)

						  async->buf_page_list[i].

						  virt_addr);

				}

			}

		}

		vfree(async->buf_page_list);

		async->buf_page_list = NULL;

		async->n_buf_pages = 0;

	}

	/*  allocate new buffer */

	if (new_size) {

		unsigned i = 0;

		unsigned n_pages = new_size >> PAGE_SHIFT;

		struct page **pages = NULL;



		async->buf_page_list =

		    vzalloc(sizeof(struct comedi_buf_page) * n_pages);

		if (async->buf_page_list)

			pages = vmalloc(sizeof(struct page *) * n_pages);



		if (pages) {

			for (i = 0; i < n_pages; i++) {

				if (s->async_dma_dir != DMA_NONE) {

					async->buf_page_list[i].virt_addr =

					    dma_alloc_coherent(dev->hw_dev,

							       PAGE_SIZE,

							       &async->

							       buf_page_list

							       [i].dma_addr,

							       GFP_KERNEL |

							       __GFP_COMP);

				} else {

					async->buf_page_list[i].virt_addr =

					    (void *)

					    get_zeroed_page(GFP_KERNEL);

				}

				if (async->buf_page_list[i].virt_addr == NULL)

					break;



				set_bit(PG_reserved,

					&(virt_to_page(async->buf_page_list[i].

							virt_addr)->flags));

				pages[i] = virt_to_page(async->buf_page_list[i].

								virt_addr);

			}

		}

		if (i == n_pages) {

			async->prealloc_buf =

#ifdef PAGE_KERNEL_NOCACHE

			    vmap(pages, n_pages, VM_MAP, PAGE_KERNEL_NOCACHE);

#else

			    vmap(pages, n_pages, VM_MAP, PAGE_KERNEL);

#endif

		}

		vfree(pages);



		if (async->prealloc_buf == NULL) {

			/* Some allocation failed above. */

			if (async->buf_page_list) {

				for (i = 0; i < n_pages; i++) {

					if (async->buf_page_list[i].virt_addr ==

					    NULL) {

						break;

					}

					clear_bit(PG_reserved,

						&(virt_to_page(async->

							buf_page_list[i].

							virt_addr)->flags));

					if (s->async_dma_dir != DMA_NONE) {

						dma_free_coherent(dev->hw_dev,

								  PAGE_SIZE,

								  async->

								  buf_page_list

								  [i].virt_addr,

								  async->

								  buf_page_list

								  [i].dma_addr);

					} else {

						free_page((unsigned long)

							  async->buf_page_list

							  [i].virt_addr);

					}

				}

				vfree(async->buf_page_list);

				async->buf_page_list = NULL;

			}

			return -ENOMEM;

		}

		async->n_buf_pages = n_pages;

	}

	async->prealloc_bufsz = new_size;



	return 0;

}



/* munging is applied to data by core as it passes between user

 * and kernel space */

static unsigned int comedi_buf_munge(struct comedi_async *async,

				     unsigned int num_bytes)

{

	struct comedi_subdevice *s = async->subdevice;

	unsigned int count = 0;

	const unsigned num_sample_bytes = bytes_per_sample(s);



	if (s->munge == NULL || (async->cmd.flags & CMDF_RAWDATA)) {

		async->munge_count += num_bytes;

		BUG_ON((int)(async->munge_count - async->buf_write_count) > 0);

		return num_bytes;

	}

	/* don't munge partial samples */

	num_bytes -= num_bytes % num_sample_bytes;

	while (count < num_bytes) {

		int block_size;



		block_size = num_bytes - count;

		if (block_size < 0) {

			dev_warn(s->device->class_dev,

				 "%s: %s: bug! block_size is negative\n",

				 __FILE__, __func__);

			break;

		}

		if ((int)(async->munge_ptr + block_size -

			  async->prealloc_bufsz) > 0)

			block_size = async->prealloc_bufsz - async->munge_ptr;



		s->munge(s->device, s, async->prealloc_buf + async->munge_ptr,

			 block_size, async->munge_chan);



		smp_wmb();	/* barrier insures data is munged in buffer

				 * before munge_count is incremented */



		async->munge_chan += block_size / num_sample_bytes;

		async->munge_chan %= async->cmd.chanlist_len;

		async->munge_count += block_size;

		async->munge_ptr += block_size;

		async->munge_ptr %= async->prealloc_bufsz;

		count += block_size;

	}

	BUG_ON((int)(async->munge_count - async->buf_write_count) > 0);

	return count;

}



unsigned int comedi_buf_write_n_available(struct comedi_async *async)

{

	unsigned int free_end;

	unsigned int nbytes;



	if (async == NULL)

		return 0;



	free_end = async->buf_read_count + async->prealloc_bufsz;

	nbytes = free_end - async->buf_write_alloc_count;

	nbytes -= nbytes % bytes_per_sample(async->subdevice);

	/* barrier insures the read of buf_read_count in this

	   query occurs before any following writes to the buffer which

	   might be based on the return value from this query.

	 */

	smp_mb();

	return nbytes;

}



/* allocates chunk for the writer from free buffer space */

unsigned int comedi_buf_write_alloc(struct comedi_async *async,

				    unsigned int nbytes)

{

	unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;



	if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0)

		nbytes = free_end - async->buf_write_alloc_count;



	async->buf_write_alloc_count += nbytes;

	/* barrier insures the read of buf_read_count above occurs before

	   we write data to the write-alloc'ed buffer space */

	smp_mb();

	return nbytes;

}

EXPORT_SYMBOL(comedi_buf_write_alloc);



/* allocates nothing unless it can completely fulfill the request */

unsigned int comedi_buf_write_alloc_strict(struct comedi_async *async,

					   unsigned int nbytes)

{

	unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;



	if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0)

		nbytes = 0;



	async->buf_write_alloc_count += nbytes;

	/* barrier insures the read of buf_read_count above occurs before

	   we write data to the write-alloc'ed buffer space */

	smp_mb();

	return nbytes;

}



/* transfers a chunk from writer to filled buffer space */

unsigned comedi_buf_write_free(struct comedi_async *async, unsigned int nbytes)

{

	if ((int)(async->buf_write_count + nbytes -

		  async->buf_write_alloc_count) > 0) {

		dev_info(async->subdevice->device->class_dev,

			 "attempted to write-free more bytes than have been write-allocated.\n");

		nbytes = async->buf_write_alloc_count - async->buf_write_count;

	}

	async->buf_write_count += nbytes;

	async->buf_write_ptr += nbytes;

	comedi_buf_munge(async, async->buf_write_count - async->munge_count);

	if (async->buf_write_ptr >= async->prealloc_bufsz)

		async->buf_write_ptr %= async->prealloc_bufsz;



	return nbytes;

}

EXPORT_SYMBOL(comedi_buf_write_free);



/* allocates a chunk for the reader from filled (and munged) buffer space */

unsigned comedi_buf_read_alloc(struct comedi_async *async, unsigned nbytes)

{

	if ((int)(async->buf_read_alloc_count + nbytes - async->munge_count) >

	    0) {

		nbytes = async->munge_count - async->buf_read_alloc_count;

	}

	async->buf_read_alloc_count += nbytes;

	/* barrier insures read of munge_count occurs before we actually read

	   data out of buffer */

	smp_rmb();

	return nbytes;

}

EXPORT_SYMBOL(comedi_buf_read_alloc);



/* transfers control of a chunk from reader to free buffer space */

unsigned comedi_buf_read_free(struct comedi_async *async, unsigned int nbytes)

{

	/* barrier insures data has been read out of

	 * buffer before read count is incremented */

	smp_mb();

	if ((int)(async->buf_read_count + nbytes -

		  async->buf_read_alloc_count) > 0) {

		dev_info(async->subdevice->device->class_dev,

			 "attempted to read-free more bytes than have been read-allocated.\n");

		nbytes = async->buf_read_alloc_count - async->buf_read_count;

	}

	async->buf_read_count += nbytes;

	async->buf_read_ptr += nbytes;

	async->buf_read_ptr %= async->prealloc_bufsz;

	return nbytes;

}

EXPORT_SYMBOL(comedi_buf_read_free);



void comedi_buf_memcpy_to(struct comedi_async *async, unsigned int offset,

			  const void *data, unsigned int num_bytes)

{

	unsigned int write_ptr = async->buf_write_ptr + offset;



	if (write_ptr >= async->prealloc_bufsz)

		write_ptr %= async->prealloc_bufsz;



	while (num_bytes) {

		unsigned int block_size;



		if (write_ptr + num_bytes > async->prealloc_bufsz)

			block_size = async->prealloc_bufsz - write_ptr;

		else

			block_size = num_bytes;



		memcpy(async->prealloc_buf + write_ptr, data, block_size);



		data += block_size;

		num_bytes -= block_size;



		write_ptr = 0;

	}

}

EXPORT_SYMBOL(comedi_buf_memcpy_to);



void comedi_buf_memcpy_from(struct comedi_async *async, unsigned int offset,

			    void *dest, unsigned int nbytes)

{

	void *src;

	unsigned int read_ptr = async->buf_read_ptr + offset;



	if (read_ptr >= async->prealloc_bufsz)

		read_ptr %= async->prealloc_bufsz;



	while (nbytes) {

		unsigned int block_size;



		src = async->prealloc_buf + read_ptr;



		if (nbytes >= async->prealloc_bufsz - read_ptr)

			block_size = async->prealloc_bufsz - read_ptr;

		else

			block_size = nbytes;



		memcpy(dest, src, block_size);

		nbytes -= block_size;

		dest += block_size;

		read_ptr = 0;

	}

}

EXPORT_SYMBOL(comedi_buf_memcpy_from);



unsigned int comedi_buf_read_n_available(struct comedi_async *async)

{

	unsigned num_bytes;



	if (async == NULL)

		return 0;

	num_bytes = async->munge_count - async->buf_read_count;

	/* barrier insures the read of munge_count in this

	   query occurs before any following reads of the buffer which

	   might be based on the return value from this query.

	 */

	smp_rmb();

	return num_bytes;

}

EXPORT_SYMBOL(comedi_buf_read_n_available);



int comedi_buf_get(struct comedi_async *async, short *x)

{

	unsigned int n = comedi_buf_read_n_available(async);



	if (n < sizeof(short))

		return 0;

	comedi_buf_read_alloc(async, sizeof(short));

	*x = *(short *)(async->prealloc_buf + async->buf_read_ptr);

	comedi_buf_read_free(async, sizeof(short));

	return 1;

}

EXPORT_SYMBOL(comedi_buf_get);



int comedi_buf_put(struct comedi_async *async, short x)

{

	unsigned int n = comedi_buf_write_alloc_strict(async, sizeof(short));



	if (n < sizeof(short)) {

		async->events |= COMEDI_CB_ERROR;

		return 0;

	}

	*(short *)(async->prealloc_buf + async->buf_write_ptr) = x;

	comedi_buf_write_free(async, sizeof(short));

	return 1;

}

EXPORT_SYMBOL(comedi_buf_put);



void comedi_reset_async_buf(struct comedi_async *async)

{

	async->buf_write_alloc_count = 0;

	async->buf_write_count = 0;

	async->buf_read_alloc_count = 0;

	async->buf_read_count = 0;



	async->buf_write_ptr = 0;

	async->buf_read_ptr = 0;



	async->cur_chan = 0;

	async->scan_progress = 0;

	async->munge_chan = 0;

	async->munge_count = 0;

	async->munge_ptr = 0;



	async->events = 0;

}



int comedi_auto_config(struct device *hardware_device,

		       struct comedi_driver *driver, unsigned long context)

{