= Standard usage =

When using a VCI-compliant component, you must define explicitely VCI parameters:

{{{
    Uses('vci_multi_ram',
	cell_size = 4,
	plen_size = 1,
	addr_size = 32,
	rerror_size = 1,
	clen_size = 1,
	rflag_size = 1,
	srcid_size = 8,
	pktid_size = 1,
	trdid_size = 1,
	wrplen_size = 1 )
}}}

When repeated for all components, this can be redundant and error prone (not even speaking of readability):

{{{
todo = Platform(
    Uses('vci_multi_ram', cell_size = 4, plen_size = 1, addr_size = 32, rerror_size = 1,
         clen_size = 1, rflag_size = 1, srcid_size = 8, pktid_size = 1, trdid_size = 1,
         wrplen_size = 1 ),
    Uses('vci_vgmn', cell_size = 4, plen_size = 1, addr_size = 32, rerror_size = 1,
         clen_size = 1, rflag_size = 1, srcid_size = 8, pktid_size = 1, trdid_size = 1,
         wrplen_size = 1 ),
    Uses('vci_xcache', cell_size = 4, plen_size = 1, addr_size = 32, rerror_size = 1,
         clen_size = 1, rflag_size = 1, srcid_size = 8, pktid_size = 1, trdid_size = 1,
         wrplen_size = 1 ),
    Uses('vci_timer', cell_size = 4, plen_size = 1, addr_size = 32, rerror_size = 1,
         clen_size = 1, rflag_size = 1, srcid_size = 8, pktid_size = 1, trdid_size = 1,
         wrplen_size = 1 ),
    Uses('mips'),
)
}}}

So you may factor out common parameters:

{{{
vci_params = dict(
	cell_size = 4,
	plen_size = 1,
	addr_size = 32,
	rerror_size = 1,
	clen_size = 1,
	rflag_size = 1,
	srcid_size = 8,
	pktid_size = 1,
	trdid_size = 1,
	wrplen_size = 1
	)

todo = Platform(
	Uses('mips'),
	Uses('vci_locks',     **vci_params),
	Uses('vci_multi_ram', **vci_params),
	Uses('vci_multi_tty', **vci_params),
	Uses('vci_timer',     **vci_params),
	Uses('vci_vgmn',      **vci_params),
	Uses('vci_xcache',    **vci_params),
	Source('top.cc'),
)
}}}

The `**variable_name` will be expanded with all the things defined in the variable, for every line, source:trunk/soclib/platforms/timer_4mips/platform_desc is a live example.

If you have some exceptionnal template parameter to add in for one component, you can specify it ''before'' the expanded one:

{{{
vci_params = dict(
	cell_size = 4,
[...]
	)

[...]
	Uses('vci_vgmn', write_buffer_depth = 16, **vci_params),
[...]
}}}