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NAME    [Toc]    [Back]

     asc -- device driver for a GI1904-based hand scanner

SYNOPSIS    [Toc]    [Back]

     device asc 1

     In /boot/device.hints:

DESCRIPTION    [Toc]    [Back]

     The asc character device driver currently handles the GI1904-based hand
     scanner (e.g. Trust Amiscan Grey).  It uses DMA and interrupts.  Up to 50
     lines of scanned input data are buffered in the driver.

     The device can operate at four different resolutions: 100, 200, 300 and
     400 dots per inch.  It produces a simple bitmap with the most significant
     bit at the left side.  The driver can optionally output the simple portable
 bitmap file format pbm(5); thus the scans can easily processed by
     most graphics packages.

     The width of the output bitmap is fixed as given by the resolution value.
     However, the height of the bitmap must be supplied when in pbm(5) mode,
     since the driver must know at what time the `end-of-file' shall be
     reached.  The default is to produce a square image; i.e., height equals
     width.  With this feature one is able to directly copy the scanner output
     into a pbm(5) file using cat(1).  One can obtain a similar effect by
     using dd(1) with the driver in raw mode.

IOCTLS    [Toc]    [Back]

     The ioctl(2) commands applicable to asc are listed below.	The sasc(1)
     provides user-level access to these commands.

     ASC_GRES	  (int) Get current resolution in dots per inch (dpi).

     ASC_GWIDTH   (int) Get current width of the bitmap in pixels.

     ASC_SHEIGHT  (int) Set the height of the bitmap in pbm(5) mode.  This is
		  actually a limit on the amount of lines scannable after the
		  first read operation.  When the limit is reached, read will
		  return 0. However, the device is turned off only when the
		  last open file descriptor is closed.

     ASC_GHEIGHT  (int) Get the current height of the bitmap.

     ASC_SBLEN	  (int) Set the length of the buffer used internally to do the
		  DMA transfer.  The buffer length is supplied in lines of the
		  bitmap.  Since the buffer size limit is (currently) 0x3000
		  bytes, the maximum number of lines allowed will vary with
		  the width of each line.  An ENOMEM error is returned if the
		  requested length would exceed this limit.

     ASC_GBLEN	  (int) Get the current buffer length in lines.

     ASC_SBTIME   (int) Set the timeout for the completion of reading one
		  buffer.  Since a handy scanner is a human/computer interface
		  timeout values are usually higher than those of a flat scanner;
 the default is 15 seconds.  After timeout is reached
		  the read operation will fail with EBUSY.  Note that the
		  timeout timer starts anew for each buffer to be read and
		  thus reducing it does not result in faster scans for longer

     ASC_GBTIME   (int) Get the current buffer timeout.

     All ioctl() requests that modify a parameter except ASC_SBTIME do not
     have an effect on an ongoing scan process.  The user must close the
     device and open it again for the new selections to take effect.  Consequently,
 the selections are not reset when the device is opened or

     Similarly, requests that read a value do not report the value that is
     used for the ongoing scan process.  The values needed during the scan
     process are saved when it starts and thus are not accessed by ioctl()

     The ASC_SBTIME value does, however, have an immediate effect on the ongoing
 scan.	Thus the timeout can, for example, be set to a large value
     until the user starts scanning, and then set to a small value to react
     (nearly) immediately when the user stops.

     Note that the pbm(5) versus raw mode selection is done by the minor number,
 not by ioctl() requests.  In raw mode, the selected height of the
     bitmap will have no effect.

FILES    [Toc]    [Back]

     /dev/asc0	  device node for raw output
     /dev/asc0d   device node for raw output, emitting debug messages if the
		  ASCDEBUG option was given in the kernel configuration file
     /dev/asc0p   device node for output in pbm(5) file format
     /dev/asc0pd  device node for pbm(5) and debug mode

SEE ALSO    [Toc]    [Back]

     sasc(1), pbm(5)

BUGS    [Toc]    [Back]

     Ioctl support is not working yet.

AUTHORS    [Toc]    [Back]

     The asc driver was written by Luigi Rizzo.

HISTORY    [Toc]    [Back]

     The asc driver first appeared in FreeBSD 2.1.

FreeBSD 5.2.1		       January 19, 1995 		 FreeBSD 5.2.1
[ Back ]
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