com.sun.electric.plugins.irsim.NewRStep Maven / Gradle / Ivy
/* -*- tab-width: 4 -*-
*
* Electric(tm) VLSI Design System
*
* File: NewRStep.java
* IRSIM simulator
* Translated by Steven M. Rubin, Sun Microsystems.
*
* Copyright (C) 1988, 1990 Stanford University.
* Permission to use, copy, modify, and distribute this
* software and its documentation for any purpose and without
* fee is hereby granted, provided that the above copyright
* notice appear in all copies. Stanford University
* makes no representations about the suitability of this
* software for any purpose. It is provided "as is" without
* express or implied warranty.
*/
package com.sun.electric.plugins.irsim;
/**
* Event-driven timing simulation step for irsim.
*
* Use diamond shape region in R-V plane for dc voltage computation.
* Use 2-pole 1-zero model for pure charge sharing delay calculations.
* Use 2-pole zero-at-origin model for driven spike analysis.
* Details of the models can be found in Chorng-Yeong Chu's thesis:
* "Improved Models for Switch-Level Simulation" also available as a
* Stanford Technical Report CSL-TR-88-368.
*/
public class NewRStep extends Eval
{
/* flags used in thevenin structure */
/** set for a definite rooted path */ private static final int T_DEFINITE = 0x01;
/** set if user specified delay encountered */ private static final int T_UDELAY = 0x02;
/** set if charge-sharing spike possible */ private static final int T_SPIKE = 0x04;
/** set if this branch is driven */ private static final int T_DRIVEN = 0x08;
/** set for the reference node in pure c-s */ private static final int T_REFNODE = 0x10;
/** set if connecting through an X trans. */ private static final int T_XTRAN = 0x20;
/** set if we should consider input slope */ private static final int T_INT = 0x40;
/** set if branch driven to dominant voltage */ private static final int T_DOMDRIVEN = 0x80;
/** nmos-pmos ratio for spike analysis */ private static final double NP_RATIO = 0.7;
private static final int SPIKETBLSIZE = 10;
private static final int NLSPKMIN = 0;
private static final int NLSPKMAX = 1;
private static final int LINEARSPK = 2;
/**
* one for each possible dominant voltage
*/
private static class Dominant
{
/** list of nodes driven to this potential */ Sim.Node nd;
/** TRUE if this pot needs spike analysis */ boolean spike;
};
private static class SpikeRec
{
/** charging delay */ double chDelay;
/** driven delay */ double drDelay;
/** spike peak */ float peak;
/** spike charge */ int charge;
}
/** dominant voltage structure */ private Dominant [] domPot;
/** 1 if debug and node is watched */ private int incLevel;
private Sim.Thev [] inputThev;
private static float spikeTable[][][] =
{
/* non-linear nmos driven low / pmos driven high */
new float[][] {
/* .01 */ new float[] {0.005f, 0.051f, 0.106f, 0.163f, 0.225f, 0.293f, 0.367f, 0.452f, 0.552f, 0.683f, 0.899f},
/* 0.1 */ new float[] {0.005f, 0.051f, 0.105f, 0.162f, 0.223f, 0.288f, 0.360f, 0.441f, 0.537f, 0.661f, 0.852f},
/* 0.2 */ new float[] {0.005f, 0.051f, 0.104f, 0.159f, 0.217f, 0.278f, 0.345f, 0.419f, 0.505f, 0.614f, 0.768f},
/* 0.3 */ new float[] {0.005f, 0.051f, 0.102f, 0.154f, 0.208f, 0.265f, 0.325f, 0.390f, 0.464f, 0.555f, 0.676f},
/* 0.4 */ new float[] {0.005f, 0.050f, 0.099f, 0.148f, 0.197f, 0.248f, 0.300f, 0.355f, 0.417f, 0.490f, 0.583f},
/* 0.5 */ new float[] {0.005f, 0.049f, 0.096f, 0.140f, 0.184f, 0.226f, 0.270f, 0.315f, 0.363f, 0.419f, 0.487f},
/* 0.6 */ new float[] {0.005f, 0.048f, 0.090f, 0.129f, 0.166f, 0.200f, 0.234f, 0.269f, 0.304f, 0.344f, 0.392f},
/* 0.7 */ new float[] {0.005f, 0.046f, 0.083f, 0.114f, 0.142f, 0.168f, 0.192f, 0.216f, 0.240f, 0.266f, 0.295f},
/* 0.8 */ new float[] {0.005f, 0.042f, 0.071f, 0.093f, 0.112f, 0.128f, 0.142f, 0.156f, 0.169f, 0.182f, 0.198f},
/* 0.9 */ new float[] {0.005f, 0.033f, 0.050f, 0.061f, 0.069f, 0.076f, 0.081f, 0.086f, 0.090f, 0.093f, 0.099f},
/* .99 */ new float[] {0.003f, 0.008f, 0.009f, 0.009f, 0.009f, 0.010f, 0.010f, 0.010f, 0.010f, 0.010f, 0.010f},
},
/* non-linear nmos driven high / pmos driven low */
new float[][] {
/* .01 */ new float[] {0.100f, 0.313f, 0.441f, 0.540f, 0.623f, 0.696f, 0.762f, 0.824f, 0.882f, 0.937f, 0.984f},
/* 0.1 */ new float[] {0.097f, 0.292f, 0.404f, 0.489f, 0.560f, 0.624f, 0.682f, 0.736f, 0.789f, 0.830f, 0.893f},
/* 0.2 */ new float[] {0.094f, 0.272f, 0.370f, 0.443f, 0.503f, 0.557f, 0.606f, 0.652f, 0.698f, 0.745f, 0.793f},
/* 0.3 */ new float[] {0.091f, 0.252f, 0.337f, 0.398f, 0.449f, 0.494f, 0.534f, 0.573f, 0.612f, 0.652f, 0.694f},
/* 0.4 */ new float[] {0.087f, 0.232f, 0.304f, 0.355f, 0.396f, 0.432f, 0.465f, 0.496f, 0.527f, 0.560f, 0.594f},
/* 0.5 */ new float[] {0.083f, 0.209f, 0.269f, 0.310f, 0.342f, 0.370f, 0.396f, 0.420f, 0.444f, 0.468f, 0.496f},
/* 0.6 */ new float[] {0.078f, 0.184f, 0.231f, 0.262f, 0.286f, 0.307f, 0.325f, 0.343f, 0.360f, 0.377f, 0.397f},
/* 0.7 */ new float[] {0.071f, 0.155f, 0.189f, 0.210f, 0.227f, 0.241f, 0.253f, 0.264f, 0.275f, 0.286f, 0.298f},
/* 0.8 */ new float[] {0.061f, 0.120f, 0.140f, 0.153f, 0.162f, 0.169f, 0.176f, 0.182f, 0.187f, 0.193f, 0.199f},
/* 0.9 */ new float[] {0.045f, 0.073f, 0.081f, 0.085f, 0.088f, 0.091f, 0.093f, 0.095f, 0.096f, 0.098f, 0.100f},
/* .99 */ new float[] {0.009f, 0.010f, 0.010f, 0.010f, 0.010f, 0.010f, 0.010f, 0.010f, 0.010f, 0.010f, 0.010f},
},
/* linear RC (nmos-pmos mix)*/
new float[][] {
/* .01 */ new float[] {0.010f, 0.099f, 0.198f, 0.296f, 0.394f, 0.491f, 0.589f, 0.688f, 0.787f, 0.887f, 0.979f},
/* 0.1 */ new float[] {0.010f, 0.095f, 0.185f, 0.272f, 0.357f, 0.441f, 0.525f, 0.610f, 0.699f, 0.792f, 0.887f},
/* 0.2 */ new float[] {0.010f, 0.091f, 0.173f, 0.250f, 0.324f, 0.396f, 0.468f, 0.541f, 0.617f, 0.699f, 0.787f},
/* 0.3 */ new float[] {0.010f, 0.087f, 0.162f, 0.230f, 0.294f, 0.355f, 0.416f, 0.477f, 0.541f, 0.610f, 0.688f},
/* 0.4 */ new float[] {0.010f, 0.083f, 0.150f, 0.209f, 0.264f, 0.315f, 0.365f, 0.416f, 0.468f, 0.525f, 0.589f},
/* 0.5 */ new float[] {0.010f, 0.078f, 0.137f, 0.188f, 0.233f, 0.275f, 0.315f, 0.355f, 0.396f, 0.441f, 0.491f},
/* 0.6 */ new float[] {0.009f, 0.072f, 0.123f, 0.164f, 0.200f, 0.233f, 0.264f, 0.294f, 0.324f, 0.357f, 0.394f},
/* 0.7 */ new float[] {0.009f, 0.065f, 0.106f, 0.138f, 0.164f, 0.188f, 0.209f, 0.230f, 0.250f, 0.272f, 0.296f},
/* 0.8 */ new float[] {0.009f, 0.055f, 0.085f, 0.106f, 0.123f, 0.137f, 0.150f, 0.162f, 0.173f, 0.185f, 0.198f},
/* 0.9 */ new float[] {0.008f, 0.039f, 0.055f, 0.065f, 0.072f, 0.078f, 0.083f, 0.087f, 0.091f, 0.095f, 0.099f},
/* .99 */ new float[] {0.004f, 0.008f, 0.009f, 0.009f, 0.009f, 0.010f, 0.010f, 0.010f, 0.010f, 0.010f, 0.010f},
}
};
private static float delayTable[][] =
{
/* .01 */ new float[] {9.12006e+00f, 6.31441e-01f, 2.57972e-01f, 1.44287e-01f,
9.08200e-02f, 6.01663e-02f, 4.03907e-02f, 2.65355e-02f,
1.61530e-02f, 7.81327e-03f, 9.32511e-04f},
/* 0.1 */ new float[] {6.75920e+01f, 4.23025e+00f, 1.67348e+00f, 9.22844e-01f,
5.78068e-01f, 3.83611e-01f, 2.59448e-01f, 1.72782e-01f,
1.07510e-01f, 5.40007e-02f, 7.10297e-03f},
/* 0.2 */ new float[] {1.19421e+02f, 7.15202e+00f, 2.80304e+00f, 1.54448e+00f,
9.70528e-01f, 6.47718e-01f, 4.41433e-01f, 2.96820e-01f,
1.86968e-01f, 9.55642e-02f, 1.30529e-02f},
/* 0.3 */ new float[] {1.63622e+02f, 9.51381e+00f, 3.72112e+00f, 2.05847e+00f,
1.30175e+00f, 8.75381e-01f, 6.01600e-01f, 4.08196e-01f,
2.59717e-01f, 1.34386e-01f, 1.87625e-02f},
/* 0.4 */ new float[] {2.01466e+02f, 1.14592e+01f, 4.49666e+00f, 2.50681e+00f,
1.59963e+00f, 1.08575e+00f, 7.53099e-01f, 5.15657e-01f,
3.31075e-01f, 1.72965e-01f, 2.44792e-02f},
/* 0.5 */ new float[] {2.33031e+02f, 1.30456e+01f, 5.16491e+00f, 2.91360e+00f,
1.88135e+00f, 1.29123e+00f, 9.04789e-01f, 6.25272e-01f,
4.04824e-01f, 2.13117e-01f, 3.03870e-02f},
/* 0.6 */ new float[] {2.57614e+02f, 1.42986e+01f, 5.75449e+00f, 3.30168e+00f,
2.16446e+00f, 1.50508e+00f, 1.06642e+00f, 7.43858e-01f,
4.85264e-01f, 2.56919e-01f, 3.66949e-02f},
/* 0.7 */ new float[] {2.73495e+02f, 1.52373e+01f, 6.30568e+00f, 3.70558e+00f,
2.47626e+00f, 1.74816e+00f, 1.25340e+00f, 8.82200e-01f,
5.79179e-01f, 3.07615e-01f, 4.37233e-02f},
/* 0.8 */ new float[] {2.76873e+02f, 1.59248e+01f, 6.91424e+00f, 4.20379e+00f,
2.87725e+00f, 2.06596e+00f, 1.49889e+00f, 1.06318e+00f,
7.00760e-01f, 3.71884e-01f, 5.21156e-02f},
/* 0.9 */ new float[] {2.57710e+02f, 1.67902e+01f, 7.96238e+00f, 5.07908e+00f,
3.57464e+00f, 2.60911e+00f, 1.90987e+00f, 1.35912e+00f,
8.94002e-01f, 4.70028e-01f, 6.37819e-02f},
/* .99 */ new float[] {1.96679e+02f, 2.57710e+01f, 1.38437e+01f, 9.11648e+00f,
6.44036e+00f, 4.66063e+00f, 3.35777e+00f, 2.33745e+00f,
1.49276e+00f, 7.51022e-01f, 9.21218e-02f}
};
public NewRStep(Sim sim)
{
super(sim);
initThevs();
theSim.tUnitDelay = 0;
theSim.tDecay = 0;
domPot = new Dominant[Sim.N_POTS];
for(int i=0; i r.rDown.min) {
reff = 1 / ( (1/r.rDown.min) - (1/r.rUp.min));
} else {
reff = 1 / ( (1/r.rUp.min) - (1/r.rDown.min));
}
tau = reff * r.cA;
} else
tau = r.rMin * r.cA;
} else if ((r.flags & T_DEFINITE) != 0)
{
tau = r.rMax * r.cA;
} else
{
tau = r.rDom * r.cA;
}
if ((r.flags & T_INT) != 0 && r.tIn > 0.5)
{
delay = Math.sqrt(tau * tau + Sim.deltaToPS((long)r.tIn) * r.cA);
} else
{
delay = tau;
}
}
queueFVal(nd, r.finall, tau, delay);
}
if (domPot[dom].spike)
{
for(Sim.Node nd = domPot[dom].nd; nd != null; nd = nd.getThev().getN())
{
r = nd.getThev();
if ((r.flags & T_SPIKE) == 0) continue;
incLevel = ((theSim.irDebug & (Sim.DEBUG_TAUP | Sim.DEBUG_TW)) == (Sim.DEBUG_TAUP | Sim.DEBUG_TW) &&
(nd.nFlags & Sim.WATCHED) != 0) ? 1 : 0;
r.tauP = getTauP(nd, (Sim.Trans) null, dom, incLevel);
r.tauP *= r.rDom / r.tauA;
queueSpike(nd, computeSpike(nd, r, dom));
}
}
}
}
private void schedulePureCS(Sim.Node nList)
{
Sim.Thev r = nList.getThev();
int dom = r.finall;
r.flags |= T_REFNODE;
double tauP = 0.0;
for(Sim.Node nd = nList; nd != null; nd = nd.nLink)
{
incLevel = ((theSim.irDebug & (Sim.DEBUG_TAU | Sim.DEBUG_TW)) == (Sim.DEBUG_TAU | Sim.DEBUG_TW) &&
(nd.nFlags & Sim.WATCHED) != 0) ? 1 : 0;
r = getTau(nd, (Sim.Trans) null, dom, incLevel);
r.tauD = r.rDom * r.cA;
switch(dom)
{
case Sim.LOW:
r.tauA = r.rDom * (r.cA - r.cD * r.v.max);
break;
case Sim.HIGH:
r.tauA = r.rDom * (r.cD * (1 - r.v.min) - r.cA);
break;
case Sim.X: // approximate Vf = 0.5
r.tauA = r.rDom * (r.cA - r.cD * 0.5);
break;
}
tauP += r.tauA * nd.nCap;
}
r = nList.getThev();
tauP = tauP / (r.cLow.min + r.cHigh.max); // tauP = tauP / CT
for(Sim.Node nd = nList; nd != null; nd = nd.nLink)
{
r = nd.getThev();
double delay = 0, tau = 0;
if (r.finall != nd.nPot)
{
switch (r.finall)
{
case Sim.LOW: tau = (r.tauA - tauP) / (1.0 - r.v.max); break;
case Sim.HIGH: tau = (tauP - r.tauA) / r.v.min; break;
case Sim.X: tau = (r.tauA - tauP) * 2.0; break;
}
if (tau < 0.0) tau = 0.0;
if (theSim.tUnitDelay != 0)
{
delay = theSim.tUnitDelay; tau = 0.0;
} else
delay = tau;
}
queueFVal(nd, r.finall, tau, delay);
}
}
/**
* Compute the final value for each node on the connection list.
* This routine will update V.min and V.max and add the node to the
* corresponding dom_driver entry. Return TRUE if any node changes value.
*/
private boolean computeDC(Sim.Node nList)
{
boolean anyChange = false;
for(Sim.Node thisOne = nList; thisOne != null; thisOne = thisOne.nLink)
{
incLevel = ((theSim.irDebug & (Sim.DEBUG_DC | Sim.DEBUG_TW)) == (Sim.DEBUG_DC | Sim.DEBUG_TW) &&
(thisOne.nFlags & Sim.WATCHED) != 0) ? 1 : 0;
Sim.Thev r = getDCVal(thisOne, null);
thisOne.setThev(r);
if (theSim.withDriven)
{
if (r.rDown.min >= Sim.LIMIT)
r.v.min = 1;
else
r.v.min = r.rDown.min / (r.rDown.min + r.rUp.max);
if (r.rUp.min >= Sim.LIMIT)
r.v.max = 0;
else
r.v.max = r.rDown.max / (r.rDown.max + r.rUp.min);
} else // use charge/total charge if undriven
{
r.v.min = r.cHigh.min / (r.cHigh.min + r.cLow.max);
r.v.max = r.cHigh.max / (r.cHigh.max + r.cLow.min);
}
if (r.v.min >= thisOne.vHigh)
r.finall = Sim.HIGH;
else if (r.v.max <= thisOne.vLow)
r.finall = Sim.LOW;
else
r.finall = Sim.X;
if (theSim.withDriven)
{
/*
* if driven and indefinite, driven value must equal
* charging value otherwise the final value is X
*/
if (r.finall != Sim.X && (r.flags & T_DEFINITE) == 0)
{
char cs_val = Sim.X;// always X
if (r.cHigh.min >= thisOne.vHigh * (r.cHigh.min + r.cLow.max))
cs_val = Sim.HIGH;
else if (r.cHigh.max <= thisOne.vLow * (r.cHigh.max + r.cLow.min))
cs_val = Sim.LOW;
if (cs_val != r.finall)
r.finall = Sim.X;
}
r.setN(domPot[r.finall].nd); // add it to list
domPot[r.finall].nd = thisOne;
// possible spike if no transition and opposite charge exists
if (r.finall == thisOne.nPot && (
(r.finall == Sim.LOW && r.cHigh.min > Sim.SMALL) ||
(r.finall == Sim.HIGH && r.cLow.min > Sim.SMALL)))
{
r.flags |= T_SPIKE;
domPot[r.finall].spike = true;
anyChange = true;
}
}
if (r.finall != thisOne.nPot)
anyChange = true;
if (((theSim.irDebug & Sim.DEBUG_DC) == Sim.DEBUG_DC &&
(thisOne.nFlags & Sim.WATCHED) != 0))
printFVal(thisOne, r);
}
return anyChange;
}
/**
* Compute the parameters used to calculate the final value (cHigh, cLow,
* rUp, rDown) by doing a depth-first traversal of the tree rooted at node
* 'n'. The traversal is done by a recursive walk through the tree. Note that
* the stage is already a simple tree; loops are broken by buildConnList. As
* a side effect also compute Req of the present transistor and all other
* transistors in parallel with it, and any specified user delays.
* The parameters are:
*
* n : the node whose dc parameters we want.
* tran : the transistor that leads to 'n' (null if none).
* level : level of recursion if we are debugging this node, else 0.
*/
private Sim.Thev getDCVal(Sim.Node n, Sim.Trans tran)
{
if ((n.nFlags & Sim.INPUT) != 0)
{
Sim.Thev r = new Sim.Thev(inputThev[n.nPot]);
return r;
}
Sim.Thev r = new Sim.Thev();
switch (n.nPot)
{
case Sim.LOW: r.cLow.min = r.cLow.max = n.nCap; break;
case Sim.X: r.cLow.max = r.cHigh.max = n.nCap; break;
case Sim.HIGH: r.cHigh.min = r.cHigh.max = n.nCap; break;
}
for(Sim.Trans t : n.nTermList)
{
// ignore path going back or through a broken loop
if (t == tran || t.state == Sim.OFF || (t.tFlags & (Sim.BROKEN | Sim.PBROKEN)) != 0)
continue;
Sim.Thev cache;
Sim.Node other;
if (n == t.source)
{
other = t.drain; cache = t.getDThev();
} else
{
other = t.source; cache = t.getSThev();
}
// if cache is not empty use the value found there, otherwise
// compute what is on the other side of the transistor and
// transmit the result through a series operation.
if (cache == null)
{
cache = seriesOP(getDCVal(other, t), t);
if (n == t.source)
{
t.setDThev(cache);
} else
{
t.setSThev(cache);
}
}
parallelOP(r, cache);
}
if ((n.nFlags & Sim.USERDELAY) != 0) // record user delays, if any
{
r.tpLH = n.tpLH; r.tpHL = n.tpHL;
r.flags |= T_UDELAY;
}
return r;
}
/**
* The following methods set Req to the appropriate dynamic resistance.
* If the transistor state is UNKNOWN then also set the T_XTRAN flag.
*/
private void getReq(Sim.Thev r, Sim.Trans t, int type)
{
if ((t.tFlags & Sim.PARALLEL) != 0)
getParallel(r, t, type);
else
{
r.req.min = t.r.dynRes[type];
if (t.state == Sim.UNKNOWN)
{
r.flags |= T_XTRAN;
} else
{
r.req.max = t.r.dynRes[type];
}
}
}
private void getMinR(Sim.Thev r, Sim.Trans t)
{
if ((t.tFlags & Sim.PARALLEL) != 0)
getMinParallel(r, t);
else
{
r.req.min = Math.min(t.r.dynRes[Sim.R_HIGH], t.r.dynRes[Sim.R_LOW]);
if (t.state == Sim.UNKNOWN)
{
r.flags |= T_XTRAN;
} else
{
r.req.max = r.req.min;
}
}
}
/**
* Do the same as getReq but deal with parallel transistors.
*/
private void getParallel(Sim.Thev r, Sim.Trans t, int restype)
{
Sim.Resists rp = t.r;
double gMin = 1.0 / rp.dynRes[restype];
double gMax = (t.state == Sim.UNKNOWN) ? 0.0 : gMin;
for(t = theSim.parallelTransistors[t.nPar]; t != null; t = t.getDTrans())
{
rp = t.r;
gMin += 1.0 / rp.dynRes[restype];
if (t.state != Sim.UNKNOWN)
gMax += 1.0 / rp.dynRes[restype];
}
r.req.min = 1.0 / gMin;
if (gMax == 0.0)
{
r.flags |= T_XTRAN;
} else
{
r.req.max = 1.0 / gMax;
}
}
/**
* Do the same as getParallel but use the minimum dynamic resistance.
*/
private void getMinParallel(Sim.Thev r, Sim.Trans t)
{
Sim.Resists rp = t.r;
double gMin = 1.0 / Math.min(rp.dynRes[Sim.R_LOW], rp.dynRes[Sim.R_HIGH]);
double gMax = (t.state == Sim.UNKNOWN) ? 0.0 : gMin;
for(t = theSim.parallelTransistors[t.nPar]; t != null; t = t.getDTrans())
{
rp = t.r;
double tmp = 1.0 / Math.min(rp.dynRes[Sim.R_LOW], rp.dynRes[Sim.R_HIGH]);
gMin += tmp;
if (t.state != Sim.UNKNOWN)
gMax += tmp;
}
r.req.min = 1.0 / gMin;
if (gMax == 0.0)
{
r.flags |= T_XTRAN;
} else
{
r.req.max = 1.0 / gMax;
}
}
/**
* Add transistor 't' in series with thevenin struct 'r'. As a side effect
* set Req for 't'. The midpoint voltage is used to determine whether to
* use the dynamic-high or dynamic-low resistance. If the branch connecting
* to 't' is not driven by an input then use the charge information. The
* current estimates of both resistance or capacitance is used.
*/
private Sim.Thev seriesOP(Sim.Thev r, Sim.Trans t)
{
if ((r.flags & T_DRIVEN) == 0)
{
if (r.cHigh.min > r.cLow.max)
getReq(r, t, Sim.R_HIGH);
else if (r.cHigh.max < r.cLow.min)
getReq(r, t, Sim.R_LOW);
else
getMinR(r, t);
return r; // no driver, so just set Req
}
if (r.rDown.min > r.rUp.max)
getReq(r, t, Sim.R_HIGH);
else if (r.rDown.max < r.rUp.min)
getReq(r, t, Sim.R_LOW);
else
getMinR(r, t);
double upMin = r.rUp.min;
double downMin = r.rDown.min;
if (upMin < Sim.LIMIT)
r.rUp.min += r.req.min * (1.0 + upMin / r.rDown.max);
if (downMin < Sim.LIMIT)
r.rDown.min += r.req.min * (1.0 + downMin / r.rUp.max);
if ((r.flags & T_XTRAN) != 0)
{
r.flags &= ~T_DEFINITE;
r.rUp.max = r.rDown.max = Sim.LARGE;
} else
{
if (r.rUp.max < Sim.LIMIT)
r.rUp.max += r.req.max * (1.0 + r.rUp.max / downMin);
if (r.rDown.max < Sim.LIMIT)
r.rDown.max += r.req.max * (1.0 + r.rDown.max / upMin);
}
return r;
}
/**
* make oldR = (oldR || newR), but watch out for infinite resistances.
*/
private double doParallel(double oldR, double newR)
{
if (oldR > Sim.LIMIT) return newR;
if (newR > Sim.LIMIT) return oldR;
return Sim.combine(oldR, newR);
}
/**
* Combine the new resistance block of the tree walk with the current one.
* Accumulate the low and high capacitances, the user-specified
* delay (if any), and the driven flag of the resulting structure.
*/
private void parallelOP(Sim.Thev r, Sim.Thev newRB)
{
r.cLow.max += newRB.cLow.max;
r.cHigh.max += newRB.cHigh.max;
if ((newRB.flags & T_XTRAN) == 0)
{
r.cLow.min += newRB.cLow.min;
r.cHigh.min += newRB.cHigh.min;
}
// Accumulate the minimum user-specified delay only if the new block
// has some drive associated with it.
if ((newRB.flags & (T_DEFINITE | T_UDELAY)) == (T_DEFINITE | T_UDELAY))
{
if ((r.flags & T_UDELAY) != 0)
{
r.tpLH = (short)Math.min(r.tpLH, newRB.tpLH);
r.tpHL = (short)Math.min(r.tpHL, newRB.tpHL);
} else
{
r.tpLH = newRB.tpLH;
r.tpHL = newRB.tpHL;
r.flags |= T_UDELAY;
}
}
if ((newRB.flags & T_DRIVEN) == 0)
return; // undriven, just update caps
r.flags |= T_DRIVEN; // combined result is driven
r.rUp.min = doParallel(r.rUp.min, newRB.rUp.min);
r.rDown.min = doParallel(r.rDown.min, newRB.rDown.min);
if ((r.flags & newRB.flags & T_DEFINITE) != 0) // both definite blocks
{
r.rUp.max = doParallel(r.rUp.max, newRB.rUp.max);
r.rDown.max = doParallel(r.rDown.max, newRB.rDown.max);
}
else if ((newRB.flags & T_DEFINITE) != 0) // only new is definite
{
r.rUp.max = newRB.rUp.max;
r.rDown.max = newRB.rDown.max;
r.flags |= T_DEFINITE; // result is definite
} else // new (perhaps r) is indefinite
{
if (newRB.rUp.max < r.rUp.max) r.rUp.max = newRB.rUp.max;
if (newRB.rDown.max < r.rDown.max) r.rDown.max = newRB.rDown.max;
}
}
/**
* Determine the input time-constant (input-slope * rStatic). We are only
* interested in transistors that just turned on (its gate has a transition
* at time == Sched.curDelta). We must be careful not to report as a transition
* nodes that stop being inputs (hist.delay == 0 and hist.inp == 0).
*/
private boolean isCurrTransition(Sim.HistEnt h)
{
return h.hTime == theSim.curDelta && (h.inp || h.delay != 0);
}
/**
* Return TRUE if we should consider the input slope of this transistor. As
* a side-effect, return the input time constant in 'ptin'.
*/
private boolean getTin(Sim.Trans t, Electric.MutableDouble ptin)
{
Sim.HistEnt h;
boolean isInt = false;
if (t.state != Sim.ON)
return false;
if ((t.tType & Sim.GATELIST) == 0)
{
h = ((Sim.Node)t.gate).curr;
if (isCurrTransition(h))
{
ptin.setValue(h.rTime * t.r.rStatic);
isInt = true;
}
} else
{
double tmp = 0.0;
for(t = (Sim.Trans) t.gate; t != null; t = t.getSTrans())
{
h = ((Sim.Node)t.gate).curr;
if (isCurrTransition(h))
{
isInt = true;
tmp += h.rTime * t.r.rStatic;
}
}
ptin.setValue(tmp);
}
return isInt;
}
/** combine 2 resistors in parallel, watch out for zero resistance */
private double combineR(double a, double b) { return ((a + b <= Sim.SMALL) ? 0 : Sim.combine(a, b)); }
private boolean getParallelTin(Sim.Trans t, Electric.MutableDouble iTau)
{
Electric.MutableDouble tin = new Electric.MutableDouble(0);
boolean isInt = getTin(t, tin);
for(t = theSim.parallelTransistors[t.nPar]; t != null; t = t.getDTrans())
{
Electric.MutableDouble tmp = new Electric.MutableDouble(0);
if (getTin(t, tmp))
{
tin.setValue(isInt ? combineR(tin.doubleValue(), tmp.doubleValue()) : tmp.doubleValue());
isInt = true;
}
iTau.setValue(tin.doubleValue());
}
return isInt;
}
/**
* Compute the parameters needed to calculate the 1st order time-constants
* (rMin, rDom, rMax, Ca, Cd, Tin) by doing a depth-first traversal of the
* tree rooted at node 'n'. The parameters are gathered by performing a
* recursive tree walk similar to computeDC. As a side effect, the tauP
* field will contain the multiplication factor to move a capacitor across
* a transistor using 'current distribution', this field may be required
* later when computing tauP. The parameters are:
*
* n : the node whose time-constant parameters we want.
* dom : the value of the dominant driver for this stage.
* tran : the transistor that leads to 'n' (null if none).
*
* This routine can be called more than once if the stage is dominated by
* more than 1 potential, hence the tauDone flag keeps track of the potential
* for which the parameters stored in the cache were computed. If the flag
* value and the current dominant potential do not match, we go ahead and
* recompute the values.
*/
private Sim.Thev getTau(Sim.Node n, Sim.Trans tran, int dom, int level)
{
Sim.Thev r;
if (tran == null)
r = n.getThev();
else
r = (tran.source == n) ? tran.getSThev() : tran.getDThev();
r.tauDone = (char)dom;
if ((n.nFlags & Sim.INPUT) != 0)
{
r.tIn = r.rMin = r.cA = r.cD = 0.0;
if (n.nPot == dom)
{
r.rDom = r.rMax = 0.0;
r.flags |= T_DOMDRIVEN;
} else
{
r.flags &= ~(T_DOMDRIVEN | T_INT);
if (dom == Sim.X)
r.rDom = r.rMax = 0.0;
else
r.rDom = r.rMax = Sim.LARGE;
}
return r;
}
if ((n.getThev().flags & T_REFNODE) != 0) // reference node in pure CS
{
r.rMin = r.rDom = r.rMax = 0.0;
r.cA = r.cD = 0.0;
return r;
}
r.rMin = r.rDom = r.rMax = Sim.LARGE;
r.cD = n.nCap;
if (dom == Sim.X) // assume X nodes are charged high
{
if (theSim.isDelayedX) {
// X nodes are charged to X through Rup and Rdown fighting
r.cA = n.nCap;
} else
r.cA = (n.nPot == Sim.LOW) ? 0.0 : n.nCap;
} else
{
r.cA = (n.nPot == dom) ? 0.0 : n.nCap;
}
r.tIn = 0.0;
r.flags &= ~(T_DOMDRIVEN | T_INT);
for(Sim.Trans t : n.nTermList)
{
if (t.state == Sim.OFF || t == tran || (t.tFlags & (Sim.BROKEN | Sim.PBROKEN)) != 0)
continue;
Sim.Node other;
Sim.Thev cache;
if (n == t.source)
{
other = t.drain; cache = t.getDThev();
} else
{
other = t.source; cache = t.getSThev();
}
if (cache.tauDone != dom)
{
Electric.MutableDouble oldR = new Electric.MutableDouble(0);
cache = getTau(other, t, dom, level + incLevel);
// Only use input slope for xtors on the dominant (driven) path
if ((cache.flags & T_DOMDRIVEN) != 0)
{
boolean inputTau = (t.tFlags & Sim.PARALLEL) != 0 ? getParallelTin(t, oldR) : getTin(t, oldR);
if (inputTau)
{
cache.flags |= T_INT;
cache.tIn += oldR.doubleValue();
}
}
oldR.setValue(cache.rDom);
cache.rMin += cache.req.min;
cache.rDom += cache.req.min;
if ((cache.flags & T_XTRAN) != 0)
{
cache.rMax = Sim.LARGE;
} else
{
cache.rMax += cache.req.max;
}
// Exclude capacitors if the other side of X transistor == dom
if ((cache.flags & T_XTRAN) != 0 && other.nPot == dom)
{
cache.tauP = cache.cA = cache.cD = 0.0;
} else if (oldR.doubleValue() > Sim.LIMIT)
{
cache.tauP = 1.0;
} else
{
cache.tauP = oldR.doubleValue() / cache.rDom;
cache.cA *= cache.tauP;
cache.cD *= cache.tauP;
}
}
r.cA += cache.cA;
r.cD += cache.cD;
r.rMin = Sim.combine(r.rMin, cache.rMin);
if (r.rDom > Sim.LIMIT)
{
r.rDom = cache.rDom;
r.rMax = cache.rMax;
} else if (cache.rDom < Sim.LIMIT)
{
r.rDom = Sim.combine(r.rDom, cache.rDom);
r.rMax = Sim.combine(r.rMax, cache.rMax);
}
if ((cache.flags & T_DOMDRIVEN) != 0)
r.flags |= T_DOMDRIVEN; // at least 1 dominant driven path
if ((cache.flags & T_INT) != 0)
{
if ((r.flags & T_INT) != 0)
r.tIn = combineR(r.tIn, cache.tIn);
else
{
r.tIn = cache.tIn;
r.flags |= T_INT;
}
}
}
if (level > 0)
printTau(n, r, level);
return r;
}
/**
* Calculate the 2nd order time constant (tauP) for the net configuration
* as seen through node 'n'. The net traversal and the parameters are
* similar to 'getTau'. Note that at this point we have not have calculated
* tauA for nodes not driven to the dominant potential, hence we need to
* compute those by first calling getTau. This routine will update the tauP
* entry as well as the tauPDone flag.
*/
private double getTauP(Sim.Node n, Sim.Trans tran, int dom, int level)
{
if ((n.nFlags & Sim.INPUT) != 0) return 0.0;
Sim.Thev r = n.getThev();
if (r.tauDone != dom) // compute tauA for the node
{
r = getTau(n, (Sim.Trans) null, dom, 0);
r.tauA = r.rDom * r.cA;
r.tauD = r.rDom * r.cD;
}
double taup = r.tauA * n.nCap;
for(Sim.Trans t : n.nTermList)
{
if (t.state == Sim.OFF || t == tran || (t.tFlags & (Sim.BROKEN | Sim.PBROKEN)) != 0)
continue;
Sim.Node other;
if (t.source == n)
{
other = t.drain; r = t.getDThev();
} else
{
other = t.source; r = t.getSThev();
}
if (r.tauPDone != dom)
{
r.tauP *= getTauP(other, t, dom, level + incLevel);
r.tauPDone = (char)dom;
}
taup += r.tauP;
}
if (level > 0)
printTauP(n, level, taup);
return taup;
}
/**
* Compute the size of spike. If the spike is too small return null, else
* fill in the appropriate structure and return a pointer to it. In order
* to determine in which table to lookup the spike peak we look at the
* conductivity of all ON transistors connected to node 'nd'; the type with
* the largest conductivity determines whether it is mostly an nmos or pmos
* network. This simple scheme should work for most simple nets.
*/
private SpikeRec computeSpike(Sim.Node nd, Sim.Thev r, int dom)
{
if (r.tauP <= Sim.SMALL) // no capacitance, no spike
{
if ((theSim.irDebug & Sim.DEBUG_SPK) != 0 && (nd.nFlags & Sim.WATCHED) != 0)
System.out.println(" spike(" + nd.nName + ") ignored (taup=0)");
return null;
}
int rType = (dom == Sim.LOW) ? Sim.R_LOW : Sim.R_HIGH;
float nmos = 0, pmos = 0;
for(Sim.Trans t : nd.nTermList)
{
if (t.state == Sim.OFF || (t.tFlags & Sim.BROKEN) != 0)
continue;
if (Sim.baseType(t.tType) == Sim.PCHAN)
pmos += 1.0f / t.r.dynRes[rType];
else
nmos += 1.0f / t.r.dynRes[rType];
}
int tabIndex = 0;
if (nmos > NP_RATIO * (pmos + nmos)) // mostly nmos
tabIndex = (rType == Sim.R_LOW) ? NLSPKMIN : NLSPKMAX;
else if (pmos > NP_RATIO * (pmos + nmos)) // mostly pmos
tabIndex = (rType == Sim.R_LOW) ? NLSPKMAX : NLSPKMIN;
else
tabIndex = LINEARSPK;
int alpha = (int) (SPIKETBLSIZE * r.tauA / (r.tauA + r.tauP - r.tauD));
if (alpha < 0) alpha = 0; else
if (alpha > SPIKETBLSIZE) alpha = SPIKETBLSIZE;
int beta = (int) (SPIKETBLSIZE * (r.tauD - r.tauA) / r.tauD);
if (beta < 0) beta = 0; else
if (beta > SPIKETBLSIZE) beta = SPIKETBLSIZE;
SpikeRec spk = new SpikeRec();
spk.peak = spikeTable[tabIndex][beta][alpha];
spk.chDelay = delayTable[beta][alpha];
if (dom == Sim.LOW)
{
if (spk.peak <= nd.vLow) // spike is too small
{
if ((theSim.irDebug & Sim.DEBUG_SPK) != 0 && (nd.nFlags & Sim.WATCHED) != 0)
printSpk(nd, r, tabIndex, dom, alpha, beta, spk, false);
return null;
}
spk.charge = (spk.peak >= nd.vHigh) ? Sim.HIGH : Sim.X;
} else // dom == HIGH
{
if (spk.peak <= 1.0 - nd.vHigh)
{
if ((theSim.irDebug & Sim.DEBUG_SPK) != 0 && (nd.nFlags & Sim.WATCHED) != 0)
printSpk(nd, r, tabIndex, dom, alpha, beta, spk, false);
return null;
}
spk.charge = (spk.peak >= 1.0 - nd.vLow) ? Sim.LOW : Sim.X;
}
spk.chDelay *= r.tauA * r.tauD / r.tauP;
if (r.rMax < Sim.LARGE)
spk.drDelay = r.rMax * r.cA;
else
spk.drDelay = r.rDom * r.cA;
if ((theSim.irDebug & Sim.DEBUG_SPK) != 0 && (nd.nFlags & Sim.WATCHED) != 0)
printSpk(nd, r, tabIndex, dom, alpha, beta, spk, true);
return spk;
}
private void printFVal(Sim.Node n, Sim.Thev r)
{
System.out.print(" final_value(" + n.nName + ") V=[" + r.v.min + ", " + r.v.max + "] => " +
Sim.vChars.charAt(r.finall));
System.out.println((r.flags & T_SPIKE) != 0 ? " (spk)" : "");
}
private void printFinal(Sim.Node nd, boolean queued, double tau, long delay)
{
Sim.Thev r = nd.getThev();
long dtau = Sim.psToDelta(tau);
System.out.print(" [event " + theSim.curNode.nName + "->" +
Sim.vChars.charAt(theSim.curNode.nPot) + " @ " + Sim.deltaToNS(theSim.curDelta) + "ns] ");
System.out.print(queued ? ("causes " + (theSim.withDriven ? "" : "CS") + "transition for") : "evaluates");
System.out.print(" " + nd.nName + ": " + Sim.vChars.charAt(nd.nPot) + " -> " + Sim.vChars.charAt(r.finall));
System.out.println(" (tau=" + Sim.deltaToPS(dtau) + "ps, delay=" + Sim.deltaToPS(delay) + "ps)");
}
private void printSpike(Sim.Node nd, SpikeRec spk, long chDelay, long drDelay)
{
System.out.print(" [event " + theSim.curNode.nName + "->" +
Sim.vChars.charAt(theSim.curNode.nPot) + "@ " + Sim.deltaToNS(theSim.curDelta) + "ns] causes ");
if (drDelay <= chDelay)
System.out.print("suppressed ");
System.out.print("spike for " + nd.nName + ": " + Sim.vChars.charAt(nd.nPot) + " -> " +
Sim.vChars.charAt(spk.charge) + " -> " + Sim.vChars.charAt(nd.nPot));
System.out.println(" (peak=" + spk.peak + " delay: ch=" + Sim.deltaToPS(chDelay) + "ps, dr=" + Sim.deltaToPS(drDelay) + "ps)");
}
private void printTauP(Sim.Node n, int level, double taup)
{
System.out.println("tauP(" + n.nName + ") = " + Sim.psToNS(taup) + " ns");
}
private void printTau(Sim.Node n, Sim.Thev r, int level)
{
System.out.println(" ...............compute_tau(" + n.nName + ")");
System.out.print (" {Rmin=" + rToAscii(r.rMin) + " Rdom=" + rToAscii(r.rDom) + " Rmax=" + rToAscii(r.rMax) + "}");
System.out.println(" {Ca=" + r.cA + " Cd=" + r.cD + "}");
System.out.print (" tauA=" + Sim.psToNS(r.rDom * r.cA) + " tauD=" + Sim.psToNS(r.rDom * r.cD) + " ns, RTin=");
if ((r.flags & T_INT) != 0)
System.out.println(Sim.deltaToNS((long)r.tIn) + " ohm*ns");
else
System.out.println("-");
}
private String rToAscii(double r)
{
if (r >= Sim.LIMIT) return " - ";
if (r > 1.0)
{
int exp = 0;
for( ; r >= 1000.0; exp++, r *= 0.001) ;
return theSim.theAnalyzer.formatDouble(r) + " KMG".charAt(exp);
}
return theSim.theAnalyzer.formatDouble(r);
}
private void printSpk(Sim.Node nd, Sim.Thev r, int tab, int dom, int alpha,
int beta, SpikeRec spk, boolean isSpk)
{
System.out.print(" spike_analysis(" + nd.nName + "):");
String net_type = "";
if (tab == LINEARSPK)
net_type = "n-p mix";
else if (tab == NLSPKMIN)
net_type = (dom == Sim.LOW) ? "nmos" : "pmos";
else
net_type = (dom == Sim.LOW) ? "pmos" : "nmos";
System.out.print(" " + net_type + " driven " + ((dom == Sim.LOW) ? "low" : "high"));
System.out.print("{tauA=" + Sim.psToNS(r.tauA) + " tauD=" + Sim.psToNS(r.tauD) + " tauP=" + Sim.psToNS(r.tauP) + "} ns ");
System.out.print("alpha=" + alpha + " beta=" + beta + " => peak=" + spk.peak);
if (isSpk)
System.out.println(" v=" + Sim.vChars.charAt(spk.charge));
else
System.out.println(" (too small)");
}
/**
* Initialize pre-initialized thevenin structs.
*/
private void initThevs()
{
inputThev = new Sim.Thev[Sim.N_POTS];
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