View source for Per region file arguments

== Current chromium impl. ==

Current chromium flashrom implements the syntax like this:

    [-i <region>[:<file>]]... -r|-w|-v [<filename>]

Where '''<filename>''' can be given anywhere on the command line (''non-positional'').

==== Rules: ====
* if no '''<filename>''' is given, all '''-i''' arguments must specify a '''<file>'''
* For reading:
** if any '''-i region:<file>''' is given along with '''<filename>''', read all included regions into '''<filename>''' and all included regions with a '''<file>''' specified into the respective file
* For writing and verifying:
** if any '''-i region:<file>''' is given along with '''<filename>''', the data of '''-i region:<file>''' takes precedence
** regions with files given with '''-i region:<file>''' must not overlap

More details: https://www.chromium.org/chromium-os/packages/cros-flashrom#TOC-Partial-Reads-and-Writes

== More explicit alternative ==

    [-i <region>]... (-r|-w|-v [<region>:]<filename>)...

Easier to implement, no optional arguments, no ''non-positional'' arguments.

==== Rules for sanity: ====

* combinations of '''-r/-w/-v''' are not allowed
* '''-r/-w/-v <filename>''' (i.e. without a '''<region>''') may only be specified once
* if no '''-r/-w/-v <filename>''' (i.e. without a '''<region>''') is specified, no '''-i''' arguments may be given either

==== optionally, stricter ====

Never mix '''<region>:<file>''' with the old '''-i''' syntax in one invocation:

    ([-i <region>]... (-r|-w|-v <filename>) | (-r|-w|-v <region>:<filename>)...)

== Files not matching the region's size ==

Both syntaxes can be extended for files that are smaller than the region:

    <region>[<filename>

would denote that the file's contents should be placed at the start/bottom
of the region,

    <region>]<filename>

that the file's contents should be placed at the end/top of the region.
By default the uncovered part of the region should be kept as is, unless

    --pad

is specified, in which case the uncovered part would be padded with the
flash chip's erased state (usually 0xff).

==== Additonal rules ====

* Beside `:`, `[` and `]` wouldn't be allowed in region names.