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First the scale factor for the time values is printed.
Each time value in the file has to be multiplied with this
factor in order to obtain the real time value.
Next, on the same line, the signals names are printed.
Each signal is enclosed between parentheses. E.g. ( signame
). When a signal name has an array specification, the name
is preceded by a left parenthesis and closed by a right
parenthesis, while the array specification directly follows
the signal name. For example:
( (in (0 6)) ) denoting in[0..6]
( (out 5 (0 7)) ) denoting out[5,0..7]
When a signal name is preceded by one or more instance
names, the instance names are printed in the same format and
precede the signal name.
E.g.
( (adder 3) in ) denoting adder[3].in
The end of the list of signal names is denoted by an end
of line character. Furthermore, in this part of the file
space characters are optional between all tokens, while they
should always be present after a signal name and between two
integers.
Next, the signal values are listed. For the different
time values on which signals change, the values of all
signals are given. Each such a specification occurs on one
line, which has a fixed length. First 15 character positions
are reserved for printing the time value. The time value
should be an integer value and it should be printed right
adjusted. Space characters should be used to precede the
integer value and to complete the 15 character positions.
Directly following the time value, the signal values are
printed with values 'h' for I, 'l'
for O, 'x' for undefined, and '.'
for previous value. No spaces should separate these items
and they should be followed by an end of line character.
Between two different signal value specifications, the
signal is assumed to have the value that was given with the
signal specification with the smallest time. The first
signal value specification should be for t=0 and there may
be more than one value specification for the same time. The
signal descriptions are valid until the time of the last
value specification.
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