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ecp5: DSCS clock propagation if modesel is 0 constant

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This commit is contained in:
rowanG077 2023-02-06 15:40:28 +01:00
parent a38ee0786a
commit d2bf44ba45
1 changed files with 102 additions and 55 deletions
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105
ecp5/pack.cc
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@ -36,6 +36,18 @@ static bool is_nextpnr_iob(Context *ctx, CellInfo *cell)
cell->type == ctx->id("$nextpnr_iobuf");
}
static bool net_is_constant(const Context *ctx, NetInfo *net, bool &value)
{
if (net == nullptr)
return false;
if (net->name == ctx->id("$PACKER_GND_NET") || net->name == ctx->id("$PACKER_VCC_NET")) {
value = (net->name == ctx->id("$PACKER_VCC_NET"));
return true;
} else {
return false;
}
}
class Ecp5Packer
{
public:
@ -2724,19 +2736,22 @@ class Ecp5Packer
} else if (ci->type == id_DCSC) {
if ((!ci->ports.count(id_CLK0) && !ci->ports.count(id_CLK1)) || !ci->ports.count(id_DCSOUT))
continue;
auto mode = str_or_default(ci->params, id_DCSMODE, "POS");
// TODO: We can do this simplification if we know
// MODESEL is tied to 0. I don't know how I can check this
// if (mode == "CLK0_LOW" || mode == "CLK0_HIGH" || mode == "CLK0") {
// copy_constraint(ci, id_CLK0, id_DCSOUT, 1.0);
// continue;
// } else if (mode == "CLK1_LOW" || mode == "CLK1_HIGH" || mode == "CLK1") {
// copy_constraint(ci, id_CLK1, id_DCSOUT, 1.0);
// continue;
// } else if (mode == "LOW" || mode == "HIGH") {
// continue;
// }
auto mode = str_or_default(ci->params, id_DCSMODE, "POS");
bool mode_constant = false;
auto mode_is_constant = net_is_constant(ctx, ci->ports.at(id_MODESEL).net, mode_constant);
if (mode_is_constant && mode_constant == false) {
if (mode == "CLK0_LOW" || mode == "CLK0_HIGH" || mode == "CLK0") {
copy_constraint(ci, id_CLK0, id_DCSOUT, 1.0);
continue;
} else if (mode == "CLK1_LOW" || mode == "CLK1_HIGH" || mode == "CLK1") {
copy_constraint(ci, id_CLK1, id_DCSOUT, 1.0);
continue;
} else if (mode == "LOW" || mode == "HIGH") {
continue;
}
}
std::unique_ptr<ClockConstraint> derived_constr = nullptr;
std::vector<NetInfo*> in_ports = {
@ -2744,25 +2759,27 @@ class Ecp5Packer
ci->ports.at(id_CLK1).net,
};
for (auto p : in_ports) {
if (p == nullptr || p->clkconstr == nullptr) {
// Generate all unique clock pairs find the worst
// constraint from switching between them and merge them
// into the final output constraint.
for (size_t i = 0; i < in_ports.size(); ++i) {
auto p1 = in_ports[i];
if (p1 == nullptr || p1->clkconstr == nullptr) {
derived_constr = nullptr;
break;
}
if (derived_constr == nullptr) {
derived_constr = std::unique_ptr<ClockConstraint>(new ClockConstraint ());
derived_constr->low = p->clkconstr->low;
derived_constr->high = p->clkconstr->high;
derived_constr->period = p->clkconstr->period;
continue;
for (size_t j = i + 1; j < in_ports.size(); ++j) {
auto p2 = in_ports[j];
if (p2 == nullptr || p2->clkconstr == nullptr) {
break;
}
auto& c1 = p1->clkconstr;
auto& c2 = p2->clkconstr;
auto& c1 = p->clkconstr;
auto& c2 = derived_constr;
auto merged_constr = std::unique_ptr<ClockConstraint>(new ClockConstraint());
if (mode == "NEG") {
derived_constr->low = DelayPair(
merged_constr->low = DelayPair(
std::min(c1->low.min_delay, c2->low.min_delay),
std::max(
c1->low.max_delay + c2->period.max_delay,
@ -2770,14 +2787,14 @@ class Ecp5Packer
)
);
} else {
derived_constr->low = DelayPair(
merged_constr->low = DelayPair(
std::min(c1->low.min_delay, c2->low.min_delay),
std::max(c1->low.max_delay, c2->low.max_delay)
);
}
if (mode == "POS") {
derived_constr->high = DelayPair(
merged_constr->high = DelayPair(
std::min(c1->high.min_delay, c2->high.min_delay),
std::max(
c1->high.max_delay + c2->period.max_delay,
@ -2785,22 +2802,52 @@ class Ecp5Packer
)
);
} else {
derived_constr->high = DelayPair(
merged_constr->high = DelayPair(
std::min(c1->high.min_delay, c2->high.min_delay),
std::max(c1->high.max_delay, c2->high.max_delay)
);
}
derived_constr->period = DelayPair(
merged_constr->period = DelayPair(
std::min(c1->period.min_delay, c2->period.min_delay),
std::max(c1->period.max_delay, c2->period.max_delay)
);
if (derived_constr == nullptr) {
derived_constr = std::move(merged_constr);
continue;
}
derived_constr->period.min_delay = std::min(
derived_constr->period.min_delay,
merged_constr->period.min_delay
);
derived_constr->period.max_delay = std::max(
derived_constr->period.max_delay,
merged_constr->period.max_delay
);
derived_constr->low.min_delay = std::min(
derived_constr->low.min_delay,
merged_constr->low.min_delay
);
derived_constr->low.max_delay = std::max(
derived_constr->low.max_delay,
merged_constr->low.max_delay
);
derived_constr->high.min_delay = std::min(
derived_constr->high.min_delay,
merged_constr->high.min_delay
);
derived_constr->high.max_delay = std::max(
derived_constr->high.max_delay,
merged_constr->high.max_delay
);
}
}
if (derived_constr != nullptr) {
set_constraint(ci, id_DCSOUT, std::move(derived_constr));
}
} else if (ci->type == id_EHXPLLL) {
delay_t period_in;
if (!get_period(ci, id_CLKI, period_in))