1nbdkit-swab-filter(1)               NBDKIT               nbdkit-swab-filter(1)
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NAME

6       nbdkit-swab-filter - nbdkit filter for swapping byte order
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SYNOPSIS

9        nbdkit --filter=swab PLUGIN [PLUGIN-ARGS...] [swab-bits=8|16|32|64]
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DESCRIPTION

12       "nbdkit-swab-filter" is a filter for nbdkit(1) which swaps bytes in the
13       underlying plugin.
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15       One use for this is to read disk images which were formatted on the
16       Atari Falcon, where the IDE controller is wired in reverse order.
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EXAMPLE

19   Swap bytes from a disk image
20        nbdkit --filter=swab file file=disk.img
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22       The above command serves the disk image disk.img, swapping even and odd
23       bytes:
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25        disk.img   0   1   2   3   4   5 ...
26                     ╳       ╳       ╳
27          output   1   0   3   2   5   4 ...
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29       This filter truncates the size of the plugin down to the alignment
30       determined by swab-bits (since operating on an unaligned tail would be
31       awkward).  If you need to round the image size up instead to access the
32       last few bytes, combine this filter with nbdkit-truncate-filter(1);
33       fortunately, sector-based disk images are already suitably sized.
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PARAMETERS

36       swab-bits=8
37           This turns off the filter.
38
39       swab-bits=16
40           This is the default setting which swaps pairs of bytes.  This is
41           suitable when reading and writing to Atari Falcon drives.
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43       swab-bits=32
44           This swaps the endianness of each 4 byte word in the disk, ie:
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46             input    0   1   2   3   4   5   6   7
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48            output    3   2   1   0   7   6   5   4
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50       swab-bits=64
51           This swaps the endianness of each 8 byte word in the disk, ie:
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53             input    0   1   2   3   4   5   6   7
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55            output    7   6   5   4   3   2   1   0
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57           This can be used to make nbdkit-pattern-plugin(1) little endian
58           instead of big endian.
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FILES

61       $filterdir/nbdkit-swab-filter.so
62           The filter.
63
64           Use "nbdkit --dump-config" to find the location of $filterdir.
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VERSION

67       "nbdkit-swab-filter" first appeared in nbdkit 1.22.
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SEE ALSO

70       nbdkit(1), nbdkit-file-plugin(1), nbdkit-pattern-plugin(1),
71       nbdkit-filter(3), nbdkit-truncate-filter(1).
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AUTHORS

74       François Revol
75

77       Copyright (C) 2020 François Revol
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LICENSE

80       Redistribution and use in source and binary forms, with or without
81       modification, are permitted provided that the following conditions are
82       met:
83
84       •   Redistributions of source code must retain the above copyright
85           notice, this list of conditions and the following disclaimer.
86
87       •   Redistributions in binary form must reproduce the above copyright
88           notice, this list of conditions and the following disclaimer in the
89           documentation and/or other materials provided with the
90           distribution.
91
92       •   Neither the name of Red Hat nor the names of its contributors may
93           be used to endorse or promote products derived from this software
94           without specific prior written permission.
95
96       THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY
97       EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
98       IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
99       PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE
100       LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
101       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
102       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
103       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
104       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
105       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
106       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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110nbdkit-1.25.8                     2021-05-25             nbdkit-swab-filter(1)
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