xref: /gem5/ext/mcpat/cacti/basic_circuit.cc

/*****************************************************************************
 *                                McPAT/CACTI
 *                      SOFTWARE LICENSE AGREEMENT
 *            Copyright 2012 Hewlett-Packard Development Company, L.P.
 *                          All Rights Reserved
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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 ***************************************************************************/




#include <cassert>
#include <cmath>
#include <iostream>

#include "basic_circuit.h"
#include "parameter.h"

uint32_t _log2(uint64_t num)
{
  uint32_t log2 = 0;

  if (num == 0)
  {
    std::cerr << "log0?" << std::endl;
    exit(1);
  }

  while (num > 1)
  {
    num = (num >> 1);
    log2++;
  }

  return log2;
}


bool is_pow2(int64_t val)
{
  if (val <= 0)
  {
    return false;
  }
  else if (val == 1)
  {
    return true;
  }
  else
  {
    return (_log2(val) != _log2(val-1));
  }
}


int powers (int base, int n)
{
  int i, p;

  p = 1;
  for (i = 1; i <= n; ++i)
    p *= base;
  return p;
}

/*----------------------------------------------------------------------*/

double logtwo (double x)
{
  assert(x > 0);
  return ((double) (log (x) / log (2.0)));
}

/*----------------------------------------------------------------------*/


double gate_C(
    double width,
    double wirelength,
    bool   _is_dram,
    bool   _is_cell,
    bool   _is_wl_tr)
{
  const TechnologyParameter::DeviceType * dt;

  if (_is_dram && _is_cell)
  {
    dt = &g_tp.dram_acc;   //DRAM cell access transistor
  }
  else if (_is_dram && _is_wl_tr)
  {
    dt = &g_tp.dram_wl;    //DRAM wordline transistor
  }
  else if (!_is_dram && _is_cell)
  {
    dt = &g_tp.sram_cell;  // SRAM cell access transistor
  }
  else
  {
    dt = &g_tp.peri_global;
  }

  return (dt->C_g_ideal + dt->C_overlap + 3*dt->C_fringe)*width + dt->l_phy*Cpolywire;
}


// returns gate capacitance in Farads
// actually this function is the same as gate_C() now
double gate_C_pass(
    double width,       // gate width in um (length is Lphy_periph_global)
    double wirelength,  // poly wire length going to gate in lambda
    bool   _is_dram,
    bool   _is_cell,
    bool   _is_wl_tr)
{
  // v5.0
  const TechnologyParameter::DeviceType * dt;

  if ((_is_dram) && (_is_cell))
  {
    dt = &g_tp.dram_acc;   //DRAM cell access transistor
  }
  else if ((_is_dram) && (_is_wl_tr))
  {
    dt = &g_tp.dram_wl;    //DRAM wordline transistor
  }
  else if ((!_is_dram) && _is_cell)
  {
    dt = &g_tp.sram_cell;  // SRAM cell access transistor
  }
  else
  {
    dt = &g_tp.peri_global;
  }

  return (dt->C_g_ideal + dt->C_overlap + 3*dt->C_fringe)*width + dt->l_phy*Cpolywire;
}



double drain_C_(
    double width,
    int nchannel,
    int stack,
    int next_arg_thresh_folding_width_or_height_cell,
    double fold_dimension,
    bool _is_dram,
    bool _is_cell,
    bool _is_wl_tr)
{
  double w_folded_tr;
  const  TechnologyParameter::DeviceType * dt;

  if ((_is_dram) && (_is_cell))
  {
    dt = &g_tp.dram_acc;   // DRAM cell access transistor
  }
  else if ((_is_dram) && (_is_wl_tr))
  {
    dt = &g_tp.dram_wl;    // DRAM wordline transistor
  }
  else if ((!_is_dram) && _is_cell)
  {
    dt = &g_tp.sram_cell;  // SRAM cell access transistor
  }
  else
  {
    dt = &g_tp.peri_global;
  }

  double c_junc_area = dt->C_junc;
  double c_junc_sidewall = dt->C_junc_sidewall;
  double c_fringe    = 2*dt->C_fringe;
  double c_overlap   = 2*dt->C_overlap;
  double drain_C_metal_connecting_folded_tr = 0;

  // determine the width of the transistor after folding (if it is getting folded)
  if (next_arg_thresh_folding_width_or_height_cell == 0)
  { // interpret fold_dimension as the the folding width threshold
    // i.e. the value of transistor width above which the transistor gets folded
    w_folded_tr = fold_dimension;
  }
  else
  { // interpret fold_dimension as the height of the cell that this transistor is part of.
    double h_tr_region  = fold_dimension - 2 * g_tp.HPOWERRAIL;
    // TODO : w_folded_tr must come from Component::compute_gate_area()
    double ratio_p_to_n = 2.0 / (2.0 + 1.0);
    if (nchannel)
    {
      w_folded_tr = (1 - ratio_p_to_n) * (h_tr_region - g_tp.MIN_GAP_BET_P_AND_N_DIFFS);
    }
    else
    {
      w_folded_tr = ratio_p_to_n * (h_tr_region - g_tp.MIN_GAP_BET_P_AND_N_DIFFS);
    }
  }
  int num_folded_tr = (int) (ceil(width / w_folded_tr));

  if (num_folded_tr < 2)
  {
    w_folded_tr = width;
  }

  double total_drain_w = (g_tp.w_poly_contact + 2 * g_tp.spacing_poly_to_contact) +  // only for drain
                         (stack - 1) * g_tp.spacing_poly_to_poly;
  double drain_h_for_sidewall = w_folded_tr;
  double total_drain_height_for_cap_wrt_gate = w_folded_tr + 2 * w_folded_tr * (stack - 1);
  if (num_folded_tr > 1)
  {
    total_drain_w += (num_folded_tr - 2) * (g_tp.w_poly_contact + 2 * g_tp.spacing_poly_to_contact) +
                     (num_folded_tr - 1) * ((stack - 1) * g_tp.spacing_poly_to_poly);

    if (num_folded_tr%2 == 0)
    {
      drain_h_for_sidewall = 0;
    }
    total_drain_height_for_cap_wrt_gate *= num_folded_tr;
    drain_C_metal_connecting_folded_tr   = g_tp.wire_local.C_per_um * total_drain_w;
  }

  double drain_C_area     = c_junc_area * total_drain_w * w_folded_tr;
  double drain_C_sidewall = c_junc_sidewall * (drain_h_for_sidewall + 2 * total_drain_w);
  double drain_C_wrt_gate = (c_fringe + c_overlap) * total_drain_height_for_cap_wrt_gate;

  return (drain_C_area + drain_C_sidewall + drain_C_wrt_gate + drain_C_metal_connecting_folded_tr);
}


double tr_R_on(
    double width,
    int nchannel,
    int stack,
    bool _is_dram,
    bool _is_cell,
    bool _is_wl_tr)
{
  const TechnologyParameter::DeviceType * dt;

  if ((_is_dram) && (_is_cell))
  {
    dt = &g_tp.dram_acc;   //DRAM cell access transistor
  }
  else if ((_is_dram) && (_is_wl_tr))
  {
    dt = &g_tp.dram_wl;    //DRAM wordline transistor
  }
  else if ((!_is_dram) && _is_cell)
  {
    dt = &g_tp.sram_cell;  // SRAM cell access transistor
  }
  else
  {
    dt = &g_tp.peri_global;
  }

  double restrans = (nchannel) ? dt->R_nch_on : dt->R_pch_on;
  return (stack * restrans / width);
}


/* This routine operates in reverse: given a resistance, it finds
 * the transistor width that would have this R.  It is used in the
 * data wordline to estimate the wordline driver size. */

// returns width in um
double R_to_w(
    double res,
    int   nchannel,
    bool _is_dram,
    bool _is_cell,
    bool _is_wl_tr)
{
  const TechnologyParameter::DeviceType * dt;

  if ((_is_dram) && (_is_cell))
  {
    dt = &g_tp.dram_acc;   //DRAM cell access transistor
  }
  else if ((_is_dram) && (_is_wl_tr))
  {
    dt = &g_tp.dram_wl;    //DRAM wordline transistor
  }
  else if ((!_is_dram) && (_is_cell))
  {
    dt = &g_tp.sram_cell;  // SRAM cell access transistor
  }
  else
  {
    dt = &g_tp.peri_global;
  }

  double restrans = (nchannel) ? dt->R_nch_on : dt->R_pch_on;
  return (restrans / res);
}


double pmos_to_nmos_sz_ratio(
    bool _is_dram,
    bool _is_wl_tr)
{
  double p_to_n_sizing_ratio;
  if ((_is_dram) && (_is_wl_tr))
  { //DRAM wordline transistor
    p_to_n_sizing_ratio = g_tp.dram_wl.n_to_p_eff_curr_drv_ratio;
  }
  else
  { //DRAM or SRAM all other transistors
    p_to_n_sizing_ratio = g_tp.peri_global.n_to_p_eff_curr_drv_ratio;
  }
  return p_to_n_sizing_ratio;
}


// "Timing Models for MOS Circuits" by Mark Horowitz, 1984
double horowitz(
    double inputramptime, // input rise time
    double tf,            // time constant of gate
    double vs1,           // threshold voltage
    double vs2,           // threshold voltage
    int    rise)          // whether input rises or fall
{
  if (inputramptime == 0 && vs1 == vs2)
  {
    return tf * (vs1 < 1 ? -log(vs1) : log(vs1));
  }
  double a, b, td;

  a = inputramptime / tf;
  if (rise == RISE)
  {
    b = 0.5;
    td = tf * sqrt(log(vs1)*log(vs1) + 2*a*b*(1.0 - vs1)) + tf*(log(vs1) - log(vs2));
  }
  else
  {
    b = 0.4;
    td = tf * sqrt(log(1.0 - vs1)*log(1.0 - vs1) + 2*a*b*(vs1)) + tf*(log(1.0 - vs1) - log(1.0 - vs2));
  }
  return (td);
}

double cmos_Ileak(
    double nWidth,
    double pWidth,
    bool _is_dram,
    bool _is_cell,
    bool _is_wl_tr)
{
  TechnologyParameter::DeviceType * dt;

  if ((!_is_dram)&&(_is_cell))
  { //SRAM cell access transistor
    dt = &(g_tp.sram_cell);
  }
  else if ((_is_dram)&&(_is_wl_tr))
  { //DRAM wordline transistor
    dt = &(g_tp.dram_wl);
  }
  else
  { //DRAM or SRAM all other transistors
    dt = &(g_tp.peri_global);
  }
  return nWidth*dt->I_off_n + pWidth*dt->I_off_p;
}


double simplified_nmos_leakage(
    double nwidth,
    bool _is_dram,
    bool _is_cell,
    bool _is_wl_tr)
{
  TechnologyParameter::DeviceType * dt;

  if ((!_is_dram)&&(_is_cell))
  { //SRAM cell access transistor
    dt = &(g_tp.sram_cell);
  }
  else if ((_is_dram)&&(_is_wl_tr))
  { //DRAM wordline transistor
    dt = &(g_tp.dram_wl);
  }
  else
  { //DRAM or SRAM all other transistors
    dt = &(g_tp.peri_global);
  }
  return nwidth * dt->I_off_n;
}

int factorial(int n, int m)
{
        int fa = m, i;
        for (i=m+1; i<=n; i++)
                fa *=i;
        return fa;
}

int combination(int n, int m)
{
  int ret;
  ret = factorial(n, m+1) / factorial(n - m);
  return ret;
}

double simplified_pmos_leakage(
    double pwidth,
    bool _is_dram,
    bool _is_cell,
    bool _is_wl_tr)
{
  TechnologyParameter::DeviceType * dt;

  if ((!_is_dram)&&(_is_cell))
  { //SRAM cell access transistor
    dt = &(g_tp.sram_cell);
  }
  else if ((_is_dram)&&(_is_wl_tr))
  { //DRAM wordline transistor
    dt = &(g_tp.dram_wl);
  }
  else
  { //DRAM or SRAM all other transistors
    dt = &(g_tp.peri_global);
  }
  return pwidth * dt->I_off_p;
}

double cmos_Ig_n(
    double nWidth,
    bool _is_dram,
    bool _is_cell,
    bool _is_wl_tr)
{
  TechnologyParameter::DeviceType * dt;

  if ((!_is_dram)&&(_is_cell))
  { //SRAM cell access transistor
    dt = &(g_tp.sram_cell);
  }
  else if ((_is_dram)&&(_is_wl_tr))
  { //DRAM wordline transistor
    dt = &(g_tp.dram_wl);
  }
  else
  { //DRAM or SRAM all other transistors
    dt = &(g_tp.peri_global);
  }
  return nWidth*dt->I_g_on_n;
}

double cmos_Ig_p(
    double pWidth,
    bool _is_dram,
    bool _is_cell,
    bool _is_wl_tr)
{
  TechnologyParameter::DeviceType * dt;

  if ((!_is_dram)&&(_is_cell))
  { //SRAM cell access transistor
    dt = &(g_tp.sram_cell);
  }
  else if ((_is_dram)&&(_is_wl_tr))
  { //DRAM wordline transistor
    dt = &(g_tp.dram_wl);
  }
  else
  { //DRAM or SRAM all other transistors
    dt = &(g_tp.peri_global);
  }
  return pWidth*dt->I_g_on_p;
}

double cmos_Isub_leakage(
    double nWidth,
    double pWidth,
    int    fanin,
    enum Gate_type g_type,
    bool _is_dram,
    bool _is_cell,
    bool _is_wl_tr,
    enum Half_net_topology topo)
{
        assert (fanin>=1);
        double nmos_leak = simplified_nmos_leakage(nWidth, _is_dram, _is_cell, _is_wl_tr);
        double pmos_leak = simplified_pmos_leakage(pWidth, _is_dram, _is_cell, _is_wl_tr);
    double Isub=0;
    int    num_states;
    int    num_off_tx;

    num_states = int(pow(2.0, fanin));

    switch (g_type)
    {
    case nmos:
        if (fanin==1)
        {
                Isub = nmos_leak/num_states;
        }
        else
        {
                if (topo==parallel)
                {
                        Isub=nmos_leak*fanin/num_states; //only when all tx are off, leakage power is non-zero. The possibility of this state is 1/num_states
                }
                else
                {
                        for (num_off_tx=1; num_off_tx<=fanin; num_off_tx++) //when num_off_tx ==0 there is no leakage power
                        {
                                //Isub += nmos_leak*pow(UNI_LEAK_STACK_FACTOR,(num_off_tx-1))*(factorial(fanin)/(factorial(fanin, num_off_tx)*factorial(num_off_tx)));
                                Isub += nmos_leak*pow(UNI_LEAK_STACK_FACTOR,(num_off_tx-1))*combination(fanin, num_off_tx);
                        }
                        Isub /=num_states;
                }

        }
        break;
    case pmos:
        if (fanin==1)
        {
                Isub = pmos_leak/num_states;
        }
        else
        {
                if (topo==parallel)
                {
                        Isub=pmos_leak*fanin/num_states; //only when all tx are off, leakage power is non-zero. The possibility of this state is 1/num_states
                }
                else
                {
                        for (num_off_tx=1; num_off_tx<=fanin; num_off_tx++) //when num_off_tx ==0 there is no leakage power
                        {
                                //Isub += pmos_leak*pow(UNI_LEAK_STACK_FACTOR,(num_off_tx-1))*(factorial(fanin)/(factorial(fanin, num_off_tx)*factorial(num_off_tx)));
                                Isub += pmos_leak*pow(UNI_LEAK_STACK_FACTOR,(num_off_tx-1))*combination(fanin, num_off_tx);
                        }
                        Isub /=num_states;
                }

        }
        break;
    case inv:
        Isub = (nmos_leak + pmos_leak)/2;
        break;
    case nand:
        Isub += fanin*pmos_leak;//the pullup network
        for (num_off_tx=1; num_off_tx<=fanin; num_off_tx++) // the pulldown network
        {
                //Isub += nmos_leak*pow(UNI_LEAK_STACK_FACTOR,(num_off_tx-1))*(factorial(fanin)/(factorial(fanin, num_off_tx)*factorial(num_off_tx)));
            Isub += nmos_leak*pow(UNI_LEAK_STACK_FACTOR,(num_off_tx-1))*combination(fanin, num_off_tx);
        }
        Isub /=num_states;
        break;
    case nor:
        for (num_off_tx=1; num_off_tx<=fanin; num_off_tx++) // the pullup network
        {
                //Isub += pmos_leak*pow(UNI_LEAK_STACK_FACTOR,(num_off_tx-1))*(factorial(fanin)/(factorial(fanin, num_off_tx)*factorial(num_off_tx)));
                Isub += pmos_leak*pow(UNI_LEAK_STACK_FACTOR,(num_off_tx-1))*combination(fanin, num_off_tx);
        }
        Isub += fanin*nmos_leak;//the pulldown network
        Isub /=num_states;
        break;
    case tri:
        Isub += (nmos_leak + pmos_leak)/2;//enabled
        Isub += nmos_leak*UNI_LEAK_STACK_FACTOR; //disabled upper bound of leakage power
        Isub /=2;
        break;
    case tg:
        Isub = (nmos_leak + pmos_leak)/2;
        break;
    default:
        assert(0);
        break;
          }

    return Isub;
}


double cmos_Ig_leakage(
    double nWidth,
    double pWidth,
    int    fanin,
    enum Gate_type g_type,
    bool _is_dram,
    bool _is_cell,
    bool _is_wl_tr,
    enum Half_net_topology topo)
{
        assert (fanin>=1);
                double nmos_leak = cmos_Ig_n(nWidth, _is_dram, _is_cell, _is_wl_tr);
                double pmos_leak = cmos_Ig_p(pWidth, _is_dram, _is_cell, _is_wl_tr);
            double Ig_on=0;
            int    num_states;
            int    num_on_tx;

            num_states = int(pow(2.0, fanin));

            switch (g_type)
            {
            case nmos:
                if (fanin==1)
                {
                        Ig_on = nmos_leak/num_states;
                }
                else
                {
                        if (topo==parallel)
                        {
                        for (num_on_tx=1; num_on_tx<=fanin; num_on_tx++)
                        {
                                Ig_on += nmos_leak*combination(fanin, num_on_tx)*num_on_tx;
                        }
                        }
                        else
                        {
                                Ig_on += nmos_leak * fanin;//pull down network when all TXs are on.
                            //num_on_tx is the number of on tx
                                for (num_on_tx=1; num_on_tx<fanin; num_on_tx++)//when num_on_tx=[1,n-1]
                                {
                                        Ig_on += nmos_leak*combination(fanin, num_on_tx)*num_on_tx/2;//TODO: this is a approximation now, a precise computation will be very complicated.
                                }
                                Ig_on /=num_states;
                        }
                }
                break;
            case pmos:
                if (fanin==1)
                {
                        Ig_on = pmos_leak/num_states;
                }
                else
                {
                        if (topo==parallel)
                    {
                  for (num_on_tx=1; num_on_tx<=fanin; num_on_tx++)
                  {
                          Ig_on += pmos_leak*combination(fanin, num_on_tx)*num_on_tx;
                  }
                    }
                    else
                    {
                          Ig_on += pmos_leak * fanin;//pull down network when all TXs are on.
                      //num_on_tx is the number of on tx
                          for (num_on_tx=1; num_on_tx<fanin; num_on_tx++)//when num_on_tx=[1,n-1]
                          {
                                  Ig_on += pmos_leak*combination(fanin, num_on_tx)*num_on_tx/2;//TODO: this is a approximation now, a precise computation will be very complicated.
                          }
                          Ig_on /=num_states;
                    }
                }
                break;

            case inv:
                Ig_on = (nmos_leak + pmos_leak)/2;
                break;
            case nand:
                //pull up network
                for (num_on_tx=1; num_on_tx<=fanin; num_on_tx++)//when num_on_tx=[1,n]
                {
                        Ig_on += pmos_leak*combination(fanin, num_on_tx)*num_on_tx;
                }

                //pull down network
                Ig_on += nmos_leak * fanin;//pull down network when all TXs are on.
                //num_on_tx is the number of on tx
                for (num_on_tx=1; num_on_tx<fanin; num_on_tx++)//when num_on_tx=[1,n-1]
                {
                        Ig_on += nmos_leak*combination(fanin, num_on_tx)*num_on_tx/2;//TODO: this is a approximation now, a precise computation will be very complicated.
                }
                Ig_on /=num_states;
                break;
            case nor:
                // num_on_tx is the number of on tx in pull up network
                Ig_on += pmos_leak * fanin;//pull up network when all TXs are on.
                for (num_on_tx=1; num_on_tx<fanin; num_on_tx++)
                {
                        Ig_on += pmos_leak*combination(fanin, num_on_tx)*num_on_tx/2;

                }
                //pull down network
                for (num_on_tx=1; num_on_tx<=fanin; num_on_tx++)//when num_on_tx=[1,n]
                {
                        Ig_on += nmos_leak*combination(fanin, num_on_tx)*num_on_tx;
                }
                Ig_on /=num_states;
                break;
            case tri:
                Ig_on += (2*nmos_leak + 2*pmos_leak)/2;//enabled
                Ig_on += (nmos_leak + pmos_leak)/2; //disabled upper bound of leakage power
                Ig_on /=2;
                break;
            case tg:
                Ig_on = (nmos_leak + pmos_leak)/2;
                break;
            default:
                assert(0);
                break;
                  }

            return Ig_on;
}

double shortcircuit_simple(
    double vt,
    double velocity_index,
    double c_in,
    double c_out,
    double w_nmos,
    double w_pmos,
    double i_on_n,
    double i_on_p,
    double i_on_n_in,
    double i_on_p_in,
    double vdd)
{

        double p_short_circuit, p_short_circuit_discharge, p_short_circuit_charge, p_short_circuit_discharge_low, p_short_circuit_discharge_high, p_short_circuit_charge_low, p_short_circuit_charge_high; //this is actually energy
        double fo_n, fo_p, fanout, beta_ratio, vt_to_vdd_ratio;

        fo_n	= i_on_n/i_on_n_in;
        fo_p	= i_on_p/i_on_p_in;
        fanout	= c_out/c_in;
        beta_ratio = i_on_p/i_on_n;
        vt_to_vdd_ratio = vt/vdd;

        //p_short_circuit_discharge_low 	= 10/3*(pow(0.5-vt_to_vdd_ratio,3.0)/pow(velocity_index,2.0)/pow(2.0,3*vt_to_vdd_ratio*vt_to_vdd_ratio))*c_in*vdd*vdd*fo_p*fo_p/fanout/beta_ratio;
        p_short_circuit_discharge_low 	= 10/3*(pow(((vdd-vt)-vt_to_vdd_ratio),3.0)/pow(velocity_index,2.0)/pow(2.0,3*vt_to_vdd_ratio*vt_to_vdd_ratio))*c_in*vdd*vdd*fo_p*fo_p/fanout/beta_ratio;
        p_short_circuit_charge_low 		= 10/3*(pow(((vdd-vt)-vt_to_vdd_ratio),3.0)/pow(velocity_index,2.0)/pow(2.0,3*vt_to_vdd_ratio*vt_to_vdd_ratio))*c_in*vdd*vdd*fo_n*fo_n/fanout*beta_ratio;
//	double t1, t2, t3, t4, t5;
//	t1=pow(((vdd-vt)-vt_to_vdd_ratio),3);
//	t2=pow(velocity_index,2.0);
//	t3=pow(2.0,3*vt_to_vdd_ratio*vt_to_vdd_ratio);
//	t4=t1/t2/t3;
//	cout <<t1<<"t1\n"<<t2<<"t2\n"<<t3<<"t3\n"<<t4<<"t4\n"<<fanout<<endl;

        p_short_circuit_discharge_high 	= pow(((vdd-vt)-vt_to_vdd_ratio),1.5)*c_in*vdd*vdd*fo_p/10/pow(2, 3*vt_to_vdd_ratio+2*velocity_index);
        p_short_circuit_charge_high 	= pow(((vdd-vt)-vt_to_vdd_ratio),1.5)*c_in*vdd*vdd*fo_n/10/pow(2, 3*vt_to_vdd_ratio+2*velocity_index);

//	t1=pow(((vdd-vt)-vt_to_vdd_ratio),1.5);
//	t2=pow(2, 3*vt_to_vdd_ratio+2*velocity_index);
//	t3=t1/t2;
//	cout <<t1<<"t1\n"<<t2<<"t2\n"<<t3<<"t3\n"<<t4<<"t4\n"<<fanout<<endl;
//	p_short_circuit_discharge = 1.0/(1.0/p_short_circuit_discharge_low + 1.0/p_short_circuit_discharge_high);
//	p_short_circuit_charge = 1/(1/p_short_circuit_charge_low + 1/p_short_circuit_charge_high); //harmmoic mean cannot be applied simple formulas.

        p_short_circuit_discharge = p_short_circuit_discharge_low;
        p_short_circuit_charge = p_short_circuit_charge_low;
        p_short_circuit = (p_short_circuit_discharge + p_short_circuit_charge)/2;

  return (p_short_circuit);
}

double shortcircuit(
    double vt,
    double velocity_index,
    double c_in,
    double c_out,
    double w_nmos,
    double w_pmos,
    double i_on_n,
    double i_on_p,
    double i_on_n_in,
    double i_on_p_in,
    double vdd)
{

        double p_short_circuit=0, p_short_circuit_discharge;//, p_short_circuit_charge, p_short_circuit_discharge_low, p_short_circuit_discharge_high, p_short_circuit_charge_low, p_short_circuit_charge_high; //this is actually energy
        double fo_n, fo_p, fanout, beta_ratio, vt_to_vdd_ratio;
        double f_alpha, k_v, e, g_v_alpha, h_v_alpha;

        fo_n		= i_on_n/i_on_n_in;
        fo_p		= i_on_p/i_on_p_in;
        fanout		= 1;
        beta_ratio 	= i_on_p/i_on_n;
        vt_to_vdd_ratio = vt/vdd;
        e 			= 	2.71828;
        f_alpha		=	1/(velocity_index+2) -velocity_index/(2*(velocity_index+3)) +velocity_index/(velocity_index+4)*(velocity_index/2-1);
        k_v			=	0.9/0.8+(vdd-vt)/0.8*log(10*(vdd-vt)/e);
        g_v_alpha	=	(velocity_index + 1)*pow((1-velocity_index),velocity_index)*pow((1-velocity_index),velocity_index/2)/f_alpha/pow((1-velocity_index-velocity_index),(velocity_index/2+velocity_index+2));
        h_v_alpha	=   pow(2, velocity_index)*(velocity_index+1)*pow((1-velocity_index),velocity_index)/pow((1-velocity_index-velocity_index),(velocity_index+1));

        //p_short_circuit_discharge_low 	= 10/3*(pow(0.5-vt_to_vdd_ratio,3.0)/pow(velocity_index,2.0)/pow(2.0,3*vt_to_vdd_ratio*vt_to_vdd_ratio))*c_in*vdd*vdd*fo_p*fo_p/fanout/beta_ratio;
//	p_short_circuit_discharge_low 	= 10/3*(pow(((vdd-vt)-vt_to_vdd_ratio),3.0)/pow(velocity_index,2.0)/pow(2.0,3*vt_to_vdd_ratio*vt_to_vdd_ratio))*c_in*vdd*vdd*fo_p*fo_p/fanout/beta_ratio;
//	p_short_circuit_charge_low 		= 10/3*(pow(((vdd-vt)-vt_to_vdd_ratio),3.0)/pow(velocity_index,2.0)/pow(2.0,3*vt_to_vdd_ratio*vt_to_vdd_ratio))*c_in*vdd*vdd*fo_n*fo_n/fanout*beta_ratio;
//	double t1, t2, t3, t4, t5;
//	t1=pow(((vdd-vt)-vt_to_vdd_ratio),3);
//	t2=pow(velocity_index,2.0);
//	t3=pow(2.0,3*vt_to_vdd_ratio*vt_to_vdd_ratio);
//	t4=t1/t2/t3;
//
//	cout <<t1<<"t1\n"<<t2<<"t2\n"<<t3<<"t3\n"<<t4<<"t4\n"<<fanout<<endl;
//
//
//	p_short_circuit_discharge_high 	= pow(((vdd-vt)-vt_to_vdd_ratio),1.5)*c_in*vdd*vdd*fo_p/10/pow(2, 3*vt_to_vdd_ratio+2*velocity_index);
//	p_short_circuit_charge_high 	= pow(((vdd-vt)-vt_to_vdd_ratio),1.5)*c_in*vdd*vdd*fo_n/10/pow(2, 3*vt_to_vdd_ratio+2*velocity_index);
//
//	p_short_circuit_discharge = 1.0/(1.0/p_short_circuit_discharge_low + 1.0/p_short_circuit_discharge_high);
//	p_short_circuit_charge = 1/(1/p_short_circuit_charge_low + 1/p_short_circuit_charge_high);
//
//	p_short_circuit = (p_short_circuit_discharge + p_short_circuit_charge)/2;
//
//	p_short_circuit = p_short_circuit_discharge;

        p_short_circuit_discharge = k_v*vdd*vdd*c_in*fo_p*fo_p/((vdd-vt)*g_v_alpha*fanout*beta_ratio/2/k_v + h_v_alpha*fo_p);
  return (p_short_circuit);
}