Avoid bit-blast I/O ports on Synopsys synthesis

[solvall]

bit blast

I have a module as shown below,

in RTL
module ABC ( PTA, PTB);
input [3:0] PTA;
output PTB;
...
endmodule


after synthesis, netlist in Gate-level obtained from Synopsys Design Compiler
module ABC ( .PTA({PTA_3, PTA_2,PTA_1,PTA_0}) , PTB);
input PTA_3,PTA2,PTA_1,PTA_0;
output PTB;
....
endmodule




I don't like this type port " .PAT({PTA_3, PTA_2,PTA_1,PTA_0})"

How can I retain bused I/O ports in verilog netlist?
My Design compiler is ver 2005-09

 

[quan228228]

bitblast

By now, i havent seen this bused I/O ports in netlist.
Anyway, This type of ports is important ? Or can you tell us your motivation?


David

 

[aji_vlsi]

what is bit blast

Hi,
DC has several variables that control the output format. A quick google search revealed this:

verilogout_single_bit

When this variable is set to true, vectored ports (or ports that use
record types) are bit-blasted; if a port’s bit vector is N bits wide, it
is written out to theVerilog file as N separate single-bit ports.When
it is set to false, all ports are written out with their original data
types. The default is true.

So try setting this variable to flase in your TCL script.

HTH
Ajeetha, CVC
www.noveldv.com

 

[solvall]

bit blasting

I did have verilogout_single_bit set as false.

but the problem is still the same as follows,

module ABC ( .PTA({PTA3, PTA2,PTA1,PTA0}),...
)
input PTA3, PTA2, PTA1, PTA0;

endmodule

-------------------------------------
I want to retain PTA as bused ports.
module ABC ( PTA ,...
)
input [3:0] PTA;

endmodule

Hi,
DC has several variables that control the output format. A quick google search revealed this:

verilogout_single_bit

When this variable is set to true, vectored ports (or ports that use
record types) are bit-blasted; if a port’s bit vector is N bits wide, it
is written out to theVerilog file as N separate single-bit ports.When
it is set to false, all ports are written out with their original data
types. The default is true.

So try setting this variable to flase in your TCL script.

HTH
Ajeetha, CVC
www.noveldv.com

 

[frankaurora]

bit-blast

you could use bus_naming_style =" %s[%d]" to fix it.