180 lines
7.4 KiB
Groff
180 lines
7.4 KiB
Groff
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.\" asc(4) - manual page for the scanner device driver `asc'
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.\"
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.\"
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.\" Copyright (c) 1995 Gunther Schadow, Luigi Rizzo. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgements:
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.\" This product includes software developed by Gunther Schadow.
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.\" This product includes software developed by Luigi Rizzo.
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.\" 4. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.TH ASC 4 "January 6, 1995" FreeBSD "FreeBSD Programmer's Manual"
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.SH NAME
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\fBasc\fP - a device driver for a handy scanner
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.SH SYNOPSIS
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.TP
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\fB#include <machine/asc_ioctl.h>\fP
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.TP
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\fBMinor number bits:\fP \fIuu d g p ...\fP
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\fIuu\fP - unit asc0 .. asc3
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\fI d\fP - selects logging of \fIdebug\fP messages
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\fI g\fP - selects \fIbitmap\fP vs. \fIgraymap\fP output
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\fI p\fP - selects \fIraw\fP vs. portable \fIpnm\fP output
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.TP
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\fBdd if=/dev/asc0 of=rawfile bs=(width/8) count=(height)
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.TP
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\fBcat /dev/asc0p > pbmfile\fP
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.PB
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.SH DESCRIPTION
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The \fBasc\fP character device driver currently handles the
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GI1904-based hand scanner (e.g. Trust Amiscan Grey).
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It uses DMA and interrupts. Input data from the scanner are
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buffered, up to 50 scanlines are buffered in the driver.
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.PP
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The device can operate at four different \fIresolutions\fP: 100, 200,
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300 and 400dpi. It produces a simple bitmap with the most significant bit
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at the left side. The driver can optionally output the famous and
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likely simple portable bitmap file format pbm(5) by Jef
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Poskanzer. Thus the scans can easily processed by any graphic package
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around (xpaint, xv, xli only to name some of them ...).
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.PP
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The \fIwidth\fP of the output bitmap is fixed as given by the
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resolution value. However, the \fIheight\fP of the bitmap must be
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supplied in \fIpnm\fP mode since the driver must know at what time the
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'end-of-file' shall be reached. The default is to produce a
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square image, i.e. \fIheight=width\fP. With this feature you are able to
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directly copy the scanner output into a pbm file whith cat(1). Of
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course you can obtain a similar effect by using dd(1) with the driver
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in \fIraw\fP mode.
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.PP
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The \fIgraymap\fP output mode is not yet implemented into the driver.
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It is even questionable if external programs would not do this job
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better thereby not counting to the size of the kernel. Even though, I
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do not know of tools which produce a graymap from a halftone bitmap.
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.SH IOCTL REQUESTS
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The ioctl requests that are served by \fBasc\fP are listed below.
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There is a utility, called sasc(1), that provides access to these
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requests from within shell.
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.TP
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ASC_GRES int
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Get current resolution in dots per inch (dpi).
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.TP
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ASC_GWIDTH int
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Get current width of the bitmap in pixels.
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.TP
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ASC_SHEIGHT int
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Set the \fIheight\fP of the bitmap in \fIpnm\fP mode. This is actually
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a limit on the amount of lines scannable after the first read
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operation. When the limit is reached read will return 0. However, the
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device is turned off only when a close is performed (either
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explicitely or implicitely on exit of the calling process).
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.TP
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ASC_GHEIGHT int
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Get the current height of the bitmap.
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.TP
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ASC_SBLEN int
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Set the length of the buffer used internally to do the DMA transfer.
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The buffer length is supplied in lines of the bitmap. Since the buffer
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size limit is (currently) 0x3000 bytes the maximum number of lines
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allowed will vary with the width of each line. This upper limit is
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checked before it overwrites the current value and pases an ENOMEM in
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the \fBerrno\fP variable. However, since the bitmap width can change
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after a buffer length was selected a read request may fail with ENOMEM
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if the buffer length turns out too high. It is generally wise to
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choose long buffers rather than go save in order to obtain better
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output.
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.TP
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ASC_GBLEN int
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Get the current buffer length in lines.
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.TP
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ASC_SBTIME int
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Set the timeout for the completion of reading one buffer. Since a
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handy scanner is a human/computer interface timeout values are usually
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higher than those of a flat scanner. Default is 15 seconds. After
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timeout is reached the read operation will fail with EBUSY. Note that
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the timeout timer starts anew for each buffer to be read and thus does
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not cause you to scan faster for longer images. BLEN/BTIME is similar
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as MIN/TIME in termios(4).
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.TP
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ASC_GBTIME int
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Get the current buffer timeout.
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.PP
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All ioctl requests that modify a parameter except ASC_SBTIME do not
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have an effect on an ongoing scan process, i.e. after the first read
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request that follows open. You must close the device and open it again
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for the new selections to take effect. Consequently, the selections
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are not reset when you close or open the device.
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.PP
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Similarily, requests that read a value do not report the value that is
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used for the ongoing scan process. The values needed during the scan
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process are saved when it starts and thus are not accessed by ioctl
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requests.
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.PP
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The BTIME value does, however, have an immediate effect on the ongoing
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scan. Thus the timeout can for example be set to long until the user
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starts scanning. It can then be set to a short amount to react
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(nearly) immediately when the user stops. Note that the user should be
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left time to at least fill one buffer without having to haste.
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.PP
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Note that the \fIpbm\fP versus \fIraw\fP mode selection is done by the
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minor number not by ioctl requests. In \fIraw\fP mode the selected
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height of the bitmap will have no effect.
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.SH FILES
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.TP 15
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.BI /dev/asc0
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device node for \fIraw\fP output, has minor number 0.
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.TP
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.BI /dev/asc0d
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device node for \fIraw\fP output emiting \fIdebug\fP messages if the
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ASCDEBUG option was given at compile time, has minor number 32.
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.TP
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.BI /dev/asc0p
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device node for output in \fIpbm\fP file format, has minor number 8.
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.TP
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.BI /dev/asc0pd
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device node for \fIpbm\fP and \fIdebug\fP mode, has minor number 40.
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.PB
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.SH DIAGNOSTICS
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.TP
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\fBASCDEBUG\fP
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When you define this name as an `option' in the kernel configuration
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you can get debug output if you access the driver with a minor number
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whose debug bit (i.e. bit 5 out of 7) is set.
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.SH SEE ALSO
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.nh
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open(2),
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ioctl(2),
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intro(2),
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read(2),
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close(2),
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cat(1),
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dd(1),
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pbm(5),
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pnm(1),
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termios(4).
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.hy
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.SH BUGS
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Ioctl support is not working yet.
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.SH AUTHOR
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Luigi Rizzo <luigi.rizzo@iet.unipi.it>
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