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Use MOS instead of bufif devices for mux optimization. 

This patch mirrors what was done in development to fix the mux
with one input as Z optimization. It should use a MOS device
instead of a bufif device.
This commit is contained in:
Cary R 2008-11-26 16:27:47 -08:00 committed by Stephen Williams
parent 8d9f7e2e26
commit b8d9f19eb0
1 changed files with 6 additions and 6 deletions
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12
cprop.cc
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@ -846,7 +846,7 @@ void cprop_functor::lpm_logic(Design*des, NetLogic*obj)
/*
* This detects the case where the mux selects between a value and
* Vz. In this case, replace the device with a bufif with the sel
* Vz. In this case, replace the device with a MOS with the sel
* input used to enable the output.
*/
void cprop_functor::lpm_mux(Design*des, NetMux*obj)
@ -880,7 +880,7 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
: verinum::Vx;
/* If only one Data input is constant, but a constant
HiZ, then we will be able to to a bufif
HiZ, then we will be able to do a MOS
substitution. */
if (cflag_a && va==verinum::Vz)
continue;
@ -913,13 +913,13 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
for (unsigned idx = 0 ; idx < obj->width() ; idx += 1) {
/* If the Sel==0 input is constant Z, make a bufif1. */
/* If the Sel==0 input is constant Z, make a NMOS. */
if (obj->pin_Data(idx, 0).nexus()->drivers_constant()
&& obj->pin_Data(idx, 0).nexus()->driven_value()==verinum::Vz) {
NetLogic*tmp = new NetLogic(scope,
scope->local_symbol(),
3, NetLogic::BUFIF1);
3, NetLogic::NMOS);
connect(result_tmp.pin(idx), tmp->pin(0));
connect(obj->pin_Data(idx,1), tmp->pin(1));
connect(obj->pin_Sel(0), tmp->pin(2));
@ -927,13 +927,13 @@ void cprop_functor::lpm_mux(Design*des, NetMux*obj)
continue;
}
/* If the Sel==1 input is constant Z, make a bufif0. */
/* If the Sel==1 input is constant Z, make a PMOS. */
if (obj->pin_Data(idx, 1).nexus()->drivers_constant()
&& obj->pin_Data(idx, 1).nexus()->driven_value()==verinum::Vz) {
NetLogic*tmp = new NetLogic(scope,
scope->local_symbol(),
3, NetLogic::BUFIF0);
3, NetLogic::PMOS);
connect(result_tmp.pin(idx), tmp->pin(0));
connect(obj->pin_Data(idx,0), tmp->pin(1));
connect(obj->pin_Sel(0), tmp->pin(2));