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XDC plugin doesn't understand port indexes properly #13

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mkurc-ant opened this issue May 7, 2020 · 5 comments · Fixed by #14
Closed

XDC plugin doesn't understand port indexes properly #13

mkurc-ant opened this issue May 7, 2020 · 5 comments · Fixed by #14

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@mkurc-ant
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It's a TCL thing. When a port is retrieved using eg. [get_ports A[10]] the TCL parser treats the port index in square brackets as another TCL command and fails there. This prevents us from using stock XDC files. A workaround for that is to specify the port like [get_ports {A[10]}].

A fix may be doing some kind of pre-processing of XDCs prior to feeding them to the Yosys' TCL interpreter.
@mithro
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mithro commented May 7, 2020

See @whitequark's twitter for how Vivado solves this problem.

@mithro
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mithro commented May 7, 2020 •
edited by unfurl-links bot

https://twitter.com/whitequark/status/1256506061462409218?s=20

Twitter
“i discovered something disturbing, but you have to know Tcl to understand it. Vivado uses Tcl for scripting FPGA flows. Vivado allows using bracketed numbers in Tcl strings, e.g. [get_ports foo[1]] works. how? they made every integer a command that returns itself but bracketed”

@mithro
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mithro commented May 7, 2020

i discovered something disturbing, but you have to know Tcl to understand it.
Vivado uses Tcl for scripting FPGA flows. Vivado allows using bracketed numbers in Tcl strings, e.g. [get_ports foo[1]] works. how?
they made every integer a command that returns itself but bracketed

@whitequark
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You can override the [unknown] command to achieve this result.

@mkurc-ant
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Thanks, that's interesting and definitely worth a shot.

@tmichalak tmichalak mentioned this issue May 12, 2020
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XDC: Fix port index parsing in get_ports command antmicro/yosys-f4pga-plugins
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@mithro @whitequark @mkurc-ant