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clockgate: prototype clock gating

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Emil J. Tywoniak 2024-09-09 15:00:54 +02:00
parent 0fc5812dcd
commit e64fceef70
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tests/techmap/clockgate.ys Normal file
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read_verilog << EOT
module dffe_00( input clk, en,
input d1, output reg q1,
);
always @( negedge clk ) begin
if ( ~en )
q1 <= d1;
end
endmodule
module dffe_01( input clk, en,
input d1, output reg q1,
);
always @( negedge clk ) begin
if ( en )
q1 <= d1;
end
endmodule
module dffe_10( input clk, en,
input d1, output reg q1,
);
always @( posedge clk ) begin
if ( ~en )
q1 <= d1;
end
endmodule
module dffe_11( input clk, en,
input d1, output reg q1,
);
always @( posedge clk ) begin
if ( en )
q1 <= d1;
end
endmodule
EOT
proc
opt
design -save before
#------------------------------------------------------------------------------
clockgate -pos pdk_icg ce:clkin:clkout -tie_lo scanen
# falling edge clock flops don't get matched on -pos
select -module dffe_00 -assert-count 0 t:\\pdk_icg
select -module dffe_01 -assert-count 0 t:\\pdk_icg
# falling edge clock flops do get matched on -pos
select -module dffe_10 -assert-count 1 t:\\pdk_icg
select -module dffe_11 -assert-count 1 t:\\pdk_icg
# if necessary, EN is inverted, since the given ICG
# is assumed to have an active-high EN
select -module dffe_10 -assert-count 1 t:\$_NOT_
select -module dffe_11 -assert-count 0 t:\$_NOT_
#------------------------------------------------------------------------------
design -load before
clockgate -min_net_size 1 -neg pdk_icg ce:clkin:clkout -tie_lo scanen
# rising edge clock flops don't get matched on -neg
select -module dffe_00 -assert-count 1 t:\\pdk_icg
select -module dffe_01 -assert-count 1 t:\\pdk_icg
# rising edge clock flops do get matched on -neg
select -module dffe_10 -assert-count 0 t:\\pdk_icg
select -module dffe_11 -assert-count 0 t:\\pdk_icg
# if necessary, EN is inverted, since the given ICG
# is assumed to have an active-high EN
select -module dffe_00 -assert-count 1 t:\$_NOT_
select -module dffe_01 -assert-count 0 t:\$_NOT_
#------------------------------------------------------------------------------
design -load before
clockgate -min_net_size 2 -neg pdk_icg ce:clkin:clkout -tie_lo scanen
# No FF set sharing a (clock, clock enable) pair is large enough
select -module dffe_00 -assert-count 0 t:\\pdk_icg
select -module dffe_01 -assert-count 0 t:\\pdk_icg
select -module dffe_10 -assert-count 0 t:\\pdk_icg
select -module dffe_11 -assert-count 0 t:\\pdk_icg
# TODO test -tie_lo