[SOLVED] How to understand an eVCD file?

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rmk423

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Hi,

I am clear about the header (with date, simulator version, timestamp, etc) & the variable definition ($var) sections in the eVCD file.

But I would like to understand how to read an event, direction & value in the value change section (after $dumpports).

For Example,

<header section>
...
<variable definition section>
...
$dumpports

<value change section>
#0
pH 0 6 <10
pU 1 2 <20
pD 3 4 <30
pL 5 6 <40
ph 7 8 <50
pl 9 10 <60
pX 11 12 <70
pD 13 14 <80
pZ 15 16 <90
pNNN 15 16 <100
pffff 0000 0000 <110
pflll 0111 0000 <120

$vcdclose #100 $end

For instance, if I know that signal A, toggles for 10 times in a period of 1 ns, through a wave viewer.

How do I map the same signal A, in the above value change section example?

Thanks,
RMK
 

The IEEE 1800-2017 LRM explains this clearly once you find it. Section 21.7.4 explains that

#0 <- the following are the signal changes for time 0

pH 0 6 <10
p -Port change
H - Output high
0 - Zero drive strength - no drive
6 - One drive strength - Strong drive
<10 - look in $var section for <10

pU 1 2 <20
p -Port change
U - Input high(up)
1 - Zero drive strength - Small Drive
2 - One drive strength - Medium drive
<20 - look in $var section for signal <20
 
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