mirror of
https://github.com/The-OpenROAD-Project/OpenSTA.git
synced 2026-05-30 00:24:12 +08:00
360 lines
12 KiB
C++
360 lines
12 KiB
C++
// OpenSTA, Static Timing Analyzer
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// Copyright (c) 2026, Parallax Software, Inc.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//
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// The origin of this software must not be misrepresented; you must not
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// claim that you wrote the original software.
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//
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// Altered source versions must be plainly marked as such, and must not be
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// misrepresented as being the original software.
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//
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// This notice may not be removed or altered from any source distribution.
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#pragma once
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#include <optional>
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#include <utility>
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#include "LibertyClass.hh"
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#include "LumpedCapDelayCalc.hh"
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namespace sta {
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class GateTableModel;
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// Base class for Dartu/Menezes/Pileggi algorithm.
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// Derived classes handle different cases of zero values in the Pi model.
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class DmpAlg : public StaState
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{
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public:
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DmpAlg(int nr_order,
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StaState *sta);
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~DmpAlg() override = default;
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virtual std::string_view name() = 0;
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// Set driver model and pi model parameters for delay calculation.
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virtual void init(const LibertyLibrary *library,
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const LibertyCell *drvr_cell,
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const Pvt *pvt,
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const GateTableModel *gate_model,
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const RiseFall *rf,
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double rd,
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double in_slew,
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double c2,
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double rpi,
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double c1);
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virtual std::pair<double, double> gateDelaySlew() = 0;
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virtual std::pair<double, double> loadDelaySlew(const Pin *load_pin,
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double elmore);
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double ceff() { return ceff_; }
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// Given x_ as a vector of input parameters, fill fvec_ with the
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// equations evaluated at x_ and fjac_ with the jabobian evaluated at x_.
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virtual void evalDmpEqns() = 0;
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// Output response to vs(t) ramp driving pi model load (vo, dvo_dt).
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std::pair<double, double> Vo(double t);
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// Load response to driver waveform (vl, dvl/dt).
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std::pair<double, double> Vl(double t);
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protected:
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void luDecomp();
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void luSolve();
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void newtonRaphson();
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// Find driver parameters t0, delta_t, Ceff.
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void findDriverParams(double ceff);
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std::pair<double, double> gateCapDelaySlew(double ceff);
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std::tuple<double, double, double> gateDelays(double ceff);
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// Partial derivatives of y(t) jacobian (dydt0, dyddt, dydcl).
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std::tuple<double, double, double> dy(double t,
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double t0,
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double dt,
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double cl);
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double y0dt(double t,
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double cl);
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double y0dcl(double t,
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double cl);
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void showX();
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void showFvec();
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void showJacobian();
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std::pair<double, double> findDriverDelaySlew();
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double findVoCrossing(double vth,
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double t_lower,
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double t_upper);
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void showVo();
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double findVlCrossing(double vth,
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double t_lower,
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double t_upper);
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void showVl();
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void fail(std::string_view reason);
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// Output response to vs(t) ramp driving capacitive load (y, t1).
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std::pair<double, double> y(double t,
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double t0,
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double dt,
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double cl);
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// Output response to unit ramp driving capacitive load.
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double y0(double t,
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double cl);
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// Output response to unit ramp driving pi model load.
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// Unit ramp output at pi load (vo, dvo_dt).
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virtual std::pair<double, double> V0(double t) = 0;
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// Upper bound on time that vo crosses vh.
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virtual double voCrossingUpperBound() = 0;
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// Load responce to driver unit ramp.
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// Unit ramp load response (vl, dvl_dt).
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virtual std::pair<double, double> Vl0(double t) = 0;
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// Upper bound on time that vl crosses vh.
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double vlCrossingUpperBound();
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// Inputs to the delay calculator.
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const LibertyCell *drvr_cell_;
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const LibertyLibrary *drvr_library_;
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const Pvt *pvt_;
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const GateTableModel *gate_model_;
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double in_slew_;
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double c2_{0.0};
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double rpi_{0.0};
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double c1_{0.0};
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double rd_;
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// Logic threshold (percentage of supply voltage).
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double vth_;
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// Slew lower limit (percentage of supply voltage).
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double vl_;
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// Slew upper limit (percentage of supply voltage).
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double vh_;
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// Table slews are scaled by slew_derate to get
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// measured slews from vl to vh.
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double slew_derate_;
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// Driver parameters calculated by this algorithm.
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double t0_;
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double dt_;
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double ceff_;
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// Driver parameter Newton-Raphson state.
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int nr_order_;
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static constexpr int max_nr_order_ = 3;
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std::array<double, max_nr_order_> x_;
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std::array<double, max_nr_order_> fvec_;
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std::array<std::array<double, max_nr_order_>, max_nr_order_> fjac_;
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std::array<double, max_nr_order_> scale_;
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std::array<double, max_nr_order_> p_;
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std::array<int, max_nr_order_> index_;
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// Driver slew used to check load delay.
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double drvr_slew_;
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double vo_delay_;
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// True if the driver parameters are valid for finding the load delays.
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bool driver_valid_;
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// Load rspf elmore delay.
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double elmore_;
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double p3_;
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// Tolerance (as a scale of value) for driver parameters (Ceff, delta t, t0).
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static constexpr double driver_param_tol_ = .01;
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// Waveform threshold crossing time tolerance (1.0 = 100%).
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static constexpr double vth_time_tol_ = .01;
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// Max iterations for findRoot.
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static constexpr int find_root_max_iter_ = 20;
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static inline int newton_raphson_max_iter_ = 100;
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// A small number used by luDecomp.
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static constexpr double tiny_double_ = 1.0e-20;
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};
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// Capacitive load.
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class DmpCap : public DmpAlg
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{
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public:
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DmpCap(StaState *sta);
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std::string_view name() override { return "cap"; }
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void init(const LibertyLibrary *library,
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const LibertyCell *drvr_cell,
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const Pvt *pvt,
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const GateTableModel *gate_model,
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const RiseFall *rf,
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double rd,
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double in_slew,
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double c2,
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double rpi,
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double c1) override;
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std::pair<double, double> gateDelaySlew() override;
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std::pair<double, double> loadDelaySlew(const Pin *,
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double elmore) override;
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void evalDmpEqns() override;
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protected:
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double voCrossingUpperBound() override;
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std::pair<double, double> V0(double t) override;
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std::pair<double, double> Vl0(double t) override;
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};
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// No non-zero pi model parameters, two poles, one zero
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class DmpPi : public DmpAlg
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{
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public:
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DmpPi(StaState *sta);
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std::string_view name() override { return "Pi"; }
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void init(const LibertyLibrary *library,
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const LibertyCell *drvr_cell,
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const Pvt *pvt,
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const GateTableModel *gate_model,
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const RiseFall *rf,
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double rd,
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double in_slew,
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double c2,
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double rpi,
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double c1) override;
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std::pair<double, double> gateDelaySlew() override;
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void evalDmpEqns() override;
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protected:
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double voCrossingUpperBound() override;
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std::pair<double, double> V0(double t) override;
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std::pair<double, double> Vl0(double t) override;
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private:
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void findDriverParamsPi();
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double ipiIceff(double t0,
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double dt,
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double ceff_time,
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double ceff);
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// Poles/zero.
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double p1_{0.0};
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double p2_{0.0};
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double z1_{0.0};
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// Residues.
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double k0_{0.0};
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double k1_{0.0};
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double k2_{0.0};
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double k3_{0.0};
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double k4_{0.0};
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// Ipi coefficients.
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double A_{0.0};
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double B_{0.0};
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double D_{0.0};
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};
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// Capacitive load, so Ceff is known.
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// Solve for t0, delta t.
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class DmpOnePole : public DmpAlg
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{
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public:
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DmpOnePole(StaState *sta);
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void evalDmpEqns() override;
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protected:
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double voCrossingUpperBound() override;
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};
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// C2 = 0, one pole, one zero.
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class DmpZeroC2 : public DmpOnePole
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{
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public:
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DmpZeroC2(StaState *sta);
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std::string_view name() override { return "c2=0"; }
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void init(const LibertyLibrary *drvr_library,
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const LibertyCell *drvr_cell,
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const Pvt *pvt,
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const GateTableModel *gate_model,
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const RiseFall *rf,
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double rd,
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double in_slew,
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double c2,
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double rpi,
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double c1) override;
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std::pair<double, double> gateDelaySlew() override;
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protected:
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std::pair<double, double> V0(double t) override;
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std::pair<double, double> Vl0(double t) override;
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double voCrossingUpperBound() override;
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private:
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// Pole/zero.
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double p1_{0.0};
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double z1_{0.0};
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// Residues.
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double k0_{0.0};
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double k1_{0.0};
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double k2_{0.0};
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double k3_{0.0};
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};
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// Delay calculator using Dartu/Menezes/Pileggi effective capacitance
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// algorithm for RSPF loads.
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class DmpCeffDelayCalc : public LumpedCapDelayCalc
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{
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public:
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DmpCeffDelayCalc(StaState *sta);
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bool reduceSupported() const override { return true; }
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ArcDcalcResult gateDelay(const Pin *drvr_pin,
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const TimingArc *arc,
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const Slew &in_slew,
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float load_cap,
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const Parasitic *parasitic,
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const LoadPinIndexMap &load_pin_index_map,
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const Scene *scene,
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const MinMax *min_max) override;
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std::string reportGateDelay(const Pin *drvr_pin,
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const TimingArc *arc,
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const Slew &in_slew,
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float load_cap,
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const Parasitic *parasitic,
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const LoadPinIndexMap &load_pin_index_map,
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const Scene *scene,
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const MinMax *min_max,
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int digits) override;
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void copyState(const StaState *sta) override;
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protected:
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virtual void loadDelaySlew(const Pin *load_pin,
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double drvr_slew,
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const RiseFall *rf,
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const LibertyLibrary *drvr_library,
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const Parasitic *parasitic,
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// Return values.
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double &wire_delay,
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double &load_slew) = 0;
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std::pair<double, double> gateDelaySlew();
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std::optional<std::pair<double, double>>
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loadDelaySlewElmore(const Pin *load_pin,
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double elmore);
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// Select the appropriate special case Dartu/Menezes/Pileggi algorithm.
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void setCeffAlgorithm(const LibertyLibrary *library,
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const LibertyCell *cell,
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const Pvt *pvt,
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const GateTableModel *gate_model,
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const RiseFall *rf,
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double in_slew,
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double c2,
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double rpi,
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double c1);
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const Parasitics *parasitics_;
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static bool unsuppored_model_warned_;
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private:
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// Dmp algorithms for each special pi model case.
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DmpCap dmp_cap_;
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DmpPi dmp_pi_;
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DmpZeroC2 dmp_zero_c2_;
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DmpAlg *dmp_alg_{nullptr};
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};
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} // namespace sta
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