wire.cc

/*****************************************************************************
 *                                CACTI 7.0
 *                      SOFTWARE LICENSE AGREEMENT
 *            Copyright 2015 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
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.”
 *
 ***************************************************************************/

#include "wire.h"
#include "cmath"
// use this constructor to calculate wire stats
Wire::Wire(
    enum Wire_type wire_model,
    double wl,
    int n,
    double w_s,
    double s_s,
    enum Wire_placement wp,
    double resistivity,
    /*TechnologyParameter::*/DeviceType *dt
    ):wt(wire_model), wire_length(wl*1e-6), nsense(n), w_scale(w_s), s_scale(s_s),
    resistivity(resistivity), deviceType(dt)
{
  wire_placement = wp;
  min_w_pmos     = deviceType->n_to_p_eff_curr_drv_ratio*g_tp.min_w_nmos_;
  in_rise_time   = 0;
  out_rise_time  = 0;
  if (initialized != 1) {
    cout << "Wire not initialized. Initializing it with default values\n";
    Wire winit;
  }
  calculate_wire_stats();
  // change everything back to seconds, microns, and Joules
  repeater_spacing *= 1e6;
  wire_length      *= 1e6;
  wire_width       *= 1e6;
  wire_spacing     *= 1e6;
  assert(wire_length > 0);
  assert(power.readOp.dynamic > 0);
  assert(power.readOp.leakage > 0);
  assert(power.readOp.gate_leakage > 0);
}

    // the following values are for peripheral global technology
    // specified in the input config file
    Component Wire::global;
    Component Wire::global_5;
    Component Wire::global_10;
    Component Wire::global_20;
    Component Wire::global_30;
    Component Wire::low_swing;

    int Wire::initialized;
    double Wire::wire_width_init;
    double Wire::wire_spacing_init;


Wire::Wire(double w_s, double s_s, enum Wire_placement wp, double resis, /*TechnologyParameter::*/DeviceType *dt)
{
  w_scale        = w_s;
  s_scale        = s_s;
  deviceType     = dt;
  wire_placement = wp;
  resistivity    = resis;
  min_w_pmos     = deviceType->n_to_p_eff_curr_drv_ratio * g_tp.min_w_nmos_;
  in_rise_time   = 0;
  out_rise_time  = 0;

  switch (wire_placement)
  {
    case outside_mat: wire_width = g_tp.wire_outside_mat.pitch/2; break;
    case inside_mat : wire_width = g_tp.wire_inside_mat.pitch/2;  break;
    default:          wire_width = g_tp.wire_local.pitch/2; break;
  }

  wire_spacing = wire_width;

  wire_width   *= (w_scale * 1e-6/2) /* (m) */;
  wire_spacing *= (s_scale * 1e-6/2) /* (m) */;

  initialized = 1;
  init_wire();
  wire_width_init = wire_width;
  wire_spacing_init = wire_spacing;

  assert(power.readOp.dynamic > 0);
  assert(power.readOp.leakage > 0);
  assert(power.readOp.gate_leakage > 0);
}



Wire::~Wire()
{
}



void
Wire::calculate_wire_stats()
{

  if (wire_placement == outside_mat) {
    wire_width = g_tp.wire_outside_mat.pitch/2;
  }
  else if (wire_placement == inside_mat) {
    wire_width = g_tp.wire_inside_mat.pitch/2;
  }
  else {
    wire_width = g_tp.wire_local.pitch/2;
  }

  wire_spacing = wire_width;

  wire_width   *= (w_scale * 1e-6/2) /* (m) */;
  wire_spacing *= (s_scale * 1e-6/2) /* (m) */;


  if (wt != Low_swing) {

	  //    delay_optimal_wire();
	  
	  if (wt == Global) {
		  delay = global.delay * wire_length;
		  power.readOp.dynamic = global.power.readOp.dynamic * wire_length;
		  power.readOp.leakage = global.power.readOp.leakage * wire_length;
		  power.readOp.gate_leakage = global.power.readOp.gate_leakage * wire_length;
		  repeater_spacing = global.area.w;
		  repeater_size = global.area.h;
		  area.set_area((wire_length/repeater_spacing) *
				  compute_gate_area(INV, 1, min_w_pmos * repeater_size,
						  g_tp.min_w_nmos_ * repeater_size, g_tp.cell_h_def));
	  }
	  else if (wt == Global_5) {
		  delay = global_5.delay * wire_length;
		  power.readOp.dynamic = global_5.power.readOp.dynamic * wire_length;
		  power.readOp.leakage = global_5.power.readOp.leakage * wire_length;
		  power.readOp.gate_leakage = global_5.power.readOp.gate_leakage * wire_length;
		  repeater_spacing = global_5.area.w;
		  repeater_size = global_5.area.h;
		  area.set_area((wire_length/repeater_spacing) *
				  compute_gate_area(INV, 1, min_w_pmos * repeater_size,
						  g_tp.min_w_nmos_ * repeater_size, g_tp.cell_h_def));
	  }
	  else if (wt == Global_10) {
		  delay = global_10.delay * wire_length;
		  power.readOp.dynamic = global_10.power.readOp.dynamic * wire_length;
		  power.readOp.leakage = global_10.power.readOp.leakage * wire_length;
		  power.readOp.gate_leakage = global_10.power.readOp.gate_leakage * wire_length;
		  repeater_spacing = global_10.area.w;
		  repeater_size = global_10.area.h;
		  area.set_area((wire_length/repeater_spacing) *
				  compute_gate_area(INV, 1, min_w_pmos * repeater_size,
						  g_tp.min_w_nmos_ * repeater_size, g_tp.cell_h_def));
	  }
	  else if (wt == Global_20) {
		  delay = global_20.delay * wire_length;
		  power.readOp.dynamic = global_20.power.readOp.dynamic * wire_length;
		  power.readOp.leakage = global_20.power.readOp.leakage * wire_length;
		  power.readOp.gate_leakage = global_20.power.readOp.gate_leakage * wire_length;
		  repeater_spacing = global_20.area.w;
		  repeater_size = global_20.area.h;
		  area.set_area((wire_length/repeater_spacing) *
				  compute_gate_area(INV, 1, min_w_pmos * repeater_size,
						  g_tp.min_w_nmos_ * repeater_size, g_tp.cell_h_def));
	  }
	  else if (wt == Global_30) {
		  delay = global_30.delay * wire_length;
		  power.readOp.dynamic = global_30.power.readOp.dynamic * wire_length;
		  power.readOp.leakage = global_30.power.readOp.leakage * wire_length;
		  power.readOp.gate_leakage = global_30.power.readOp.gate_leakage * wire_length;
		  repeater_spacing = global_30.area.w;
		  repeater_size = global_30.area.h;
		  area.set_area((wire_length/repeater_spacing) *
				  compute_gate_area(INV, 1, min_w_pmos * repeater_size,
						  g_tp.min_w_nmos_ * repeater_size, g_tp.cell_h_def));
	  }
    out_rise_time = delay*repeater_spacing/deviceType->Vth;
  }
  else if (wt == Low_swing) {
    low_swing_model ();
    repeater_spacing = wire_length;
    repeater_size = 1;
  }
  else {
    assert(0);
  }
}



/*
 * The fall time of an input signal to the first stage of a circuit is
 * assumed to be same as the fall time of the output signal of two
 * inverters connected in series (refer: CACTI 1 Technical report,
 * section 6.1.3)
 */
  double
Wire::signal_fall_time ()
{

  /* rise time of inverter 1's output */
  double rt;
  /* fall time of inverter 2's output */
  double ft;
  double timeconst;

  timeconst = (drain_C_(g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def) +
      drain_C_(min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
      gate_C(min_w_pmos + g_tp.min_w_nmos_, 0)) *
    tr_R_on(min_w_pmos, PCH, 1);
  rt = horowitz (0, timeconst, deviceType->Vth/deviceType->Vdd, deviceType->Vth/deviceType->Vdd, FALL) / (deviceType->Vdd - deviceType->Vth);
  timeconst = (drain_C_(g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def) +
      drain_C_(min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
      gate_C(min_w_pmos + g_tp.min_w_nmos_, 0)) *
    tr_R_on(g_tp.min_w_nmos_, NCH, 1);
  ft = horowitz (rt, timeconst, deviceType->Vth/deviceType->Vdd, deviceType->Vth/deviceType->Vdd, RISE) / deviceType->Vth;
  return ft;
}



double Wire::signal_rise_time ()
{

  /* rise time of inverter 1's output */
  double ft;
  /* fall time of inverter 2's output */
  double rt;
  double timeconst;

  timeconst = (drain_C_(g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def) +
      drain_C_(min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
      gate_C(min_w_pmos + g_tp.min_w_nmos_, 0)) *
    tr_R_on(g_tp.min_w_nmos_, NCH, 1);
  rt = horowitz (0, timeconst, deviceType->Vth/deviceType->Vdd, deviceType->Vth/deviceType->Vdd, RISE) / deviceType->Vth;
  timeconst = (drain_C_(g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def) +
      drain_C_(min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
      gate_C(min_w_pmos + g_tp.min_w_nmos_, 0)) *
    tr_R_on(min_w_pmos, PCH, 1);
  ft = horowitz (rt, timeconst, deviceType->Vth/deviceType->Vdd, deviceType->Vth/deviceType->Vdd, FALL) / (deviceType->Vdd - deviceType->Vth);
  return ft; //sec
}



/* Wire resistance and capacitance calculations
 *   wire width
 *
 *    /__/
 *   |  |
 *   |  |  height = ASPECT_RATIO*wire width (ASPECT_RATIO = 2.2, ref: ITRS)
 *   |__|/
 *
 *   spacing between wires in same level = wire width
 *
 */

double Wire::wire_cap (double len /* in m */, bool call_from_outside)
{
	//TODO: this should be consistent with the wire_res in technology file
  double sidewall, adj, tot_cap;
  double wire_height;
  double epsilon0 = 8.8542e-12;
  double aspect_ratio, horiz_dielectric_constant, vert_dielectric_constant, miller_value,ild_thickness;

  switch (wire_placement)
  {
    case outside_mat:
    	{
    		aspect_ratio = g_tp.wire_outside_mat.aspect_ratio;
    		horiz_dielectric_constant = g_tp.wire_outside_mat.horiz_dielectric_constant;
    		vert_dielectric_constant = g_tp.wire_outside_mat.vert_dielectric_constant;
    		miller_value = g_tp.wire_outside_mat.miller_value;
    		ild_thickness = g_tp.wire_outside_mat.ild_thickness;
    		break;
    	}
    case inside_mat :
    	{
    		aspect_ratio = g_tp.wire_inside_mat.aspect_ratio;
    		horiz_dielectric_constant = g_tp.wire_inside_mat.horiz_dielectric_constant;
    		vert_dielectric_constant = g_tp.wire_inside_mat.vert_dielectric_constant;
    		miller_value = g_tp.wire_inside_mat.miller_value;
    		ild_thickness = g_tp.wire_inside_mat.ild_thickness;
    		break;
    	}
    default:
    	{
    		aspect_ratio = g_tp.wire_local.aspect_ratio;
    		horiz_dielectric_constant = g_tp.wire_local.horiz_dielectric_constant;
    		vert_dielectric_constant = g_tp.wire_local.vert_dielectric_constant;
    		miller_value = g_tp.wire_local.miller_value;
    		ild_thickness = g_tp.wire_local.ild_thickness;
    		break;
    	}
  }

  if (call_from_outside)
  {
	  wire_width       *= 1e-6;
	  wire_spacing     *= 1e-6;
  }
  wire_height = wire_width/w_scale*aspect_ratio;
  /*
   * assuming height does not change. wire_width = width_original*w_scale
   * So wire_height does not change as wire width increases
   */

// capacitance between wires in the same level
//  sidewall = 2*miller_value * horiz_dielectric_constant * (wire_height/wire_spacing)
//    * epsilon0;

  sidewall = miller_value * horiz_dielectric_constant * (wire_height/wire_spacing)
    * epsilon0;


  // capacitance between wires in adjacent levels
  //adj = miller_value * vert_dielectric_constant *w_scale * epsilon0;
  //adj = 2*vert_dielectric_constant *wire_width/(ild_thickness*1e-6) * epsilon0;

  adj = miller_value *vert_dielectric_constant *wire_width/(ild_thickness*1e-6) * epsilon0;
  //Change ild_thickness from micron to M

  //tot_cap =  (sidewall + adj + (deviceType->C_fringe * 1e6)); //F/m
  tot_cap =  (sidewall + adj + (g_tp.fringe_cap * 1e6)); //F/m

  if (call_from_outside)
  {
	  wire_width       *= 1e6;
	  wire_spacing     *= 1e6;
  }
  return (tot_cap*len); // (F)
}


  double
Wire::wire_res (double len /*(in m)*/)
{

	  double aspect_ratio,alpha_scatter =1.05, dishing_thickness=0, barrier_thickness=0;
	  //TODO: this should be consistent with the wire_res in technology file
	  //The whole computation should be consistent with the wire_res in technology.cc too!

	  switch (wire_placement)
	  {
	  case outside_mat:
	  {
		  aspect_ratio = g_tp.wire_outside_mat.aspect_ratio;
		  break;
	  }
	  case inside_mat :
	  {
		  aspect_ratio = g_tp.wire_inside_mat.aspect_ratio;
		  break;
	  }
	  default:
	  {
		  aspect_ratio = g_tp.wire_local.aspect_ratio;
		  break;
	  }
	  }
	  return (alpha_scatter * resistivity * 1e-6 * len/((aspect_ratio*wire_width/w_scale-dishing_thickness - barrier_thickness)*
			  (wire_width-2*barrier_thickness)));
}

/*
 * Calculates the delay, power and area of the transmitter circuit.
 *
 * The transmitter delay is the sum of nand gate delay, inverter delay
 * low swing nmos delay, and the wire delay
 * (ref: Technical report 6)
 */
  void
Wire::low_swing_model()
{
  double len = wire_length;
  double beta = pmos_to_nmos_sz_ratio();


  double inputrise = (in_rise_time == 0) ? signal_rise_time() : in_rise_time;

  /* Final nmos low swing driver size calculation:
   * Try to size the driver such that the delay
   * is less than 8FO4.
   * If the driver size is greater than
   * the max allowable size, assume max size for the driver.
   * In either case, recalculate the delay using
   * the final driver size assuming slow input with
   * finite rise time instead of ideal step input
   *
   * (ref: Technical report 6)
   */
  double cwire = wire_cap(len); /* load capacitance */
  double rwire = wire_res(len);

#define RES_ADJ (8.6) // Increase in resistance due to low driving vol.

  double driver_res = (-8*g_tp.FO4/(log(0.5) * cwire))/RES_ADJ;
  double nsize = R_to_w(driver_res, NCH);

  nsize = MIN(nsize, g_tp.max_w_nmos_);
  nsize = MAX(nsize, g_tp.min_w_nmos_);

  if(rwire*cwire > 8*g_tp.FO4)
  {
    nsize = g_tp.max_w_nmos_;
  }

  // size the inverter appropriately to minimize the transmitter delay
  // Note - In order to minimize leakage, we are not adding a set of inverters to
  // bring down delay. Instead, we are sizing the single gate
  // based on the logical effort.
  double st_eff   = sqrt((2+beta/1+beta)*gate_C(nsize, 0)/(gate_C(2*g_tp.min_w_nmos_, 0)
        + gate_C(2*min_w_pmos, 0)));
  double req_cin  = ((2+beta/1+beta)*gate_C(nsize, 0))/st_eff;
  double inv_size = req_cin/(gate_C(min_w_pmos, 0) + gate_C(g_tp.min_w_nmos_, 0));
  inv_size = MAX(inv_size, 1);

  /* nand gate delay */
  double res_eq = (2 * tr_R_on(g_tp.min_w_nmos_, NCH, 1));
  double cap_eq = 2 * drain_C_(min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
    drain_C_(2*g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def) +
    gate_C(inv_size*g_tp.min_w_nmos_, 0) +
    gate_C(inv_size*min_w_pmos, 0);

  double timeconst = res_eq * cap_eq;

  delay = horowitz(inputrise, timeconst, deviceType->Vth/deviceType->Vdd,
      deviceType->Vth/deviceType->Vdd, RISE);
  double temp_power = cap_eq*deviceType->Vdd*deviceType->Vdd;

  inputrise = delay / (deviceType->Vdd - deviceType->Vth); /* for the next stage */

  /* Inverter delay:
   * The load capacitance of this inv depends on
   * the gate capacitance of the final stage nmos
   * transistor which in turn depends on nsize
   */
  res_eq = tr_R_on(inv_size*min_w_pmos, PCH, 1);
  cap_eq = drain_C_(inv_size*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
    drain_C_(inv_size*g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def) +
    gate_C(nsize, 0);
  timeconst = res_eq * cap_eq;

  delay += horowitz(inputrise, timeconst, deviceType->Vth/deviceType->Vdd,
      deviceType->Vth/deviceType->Vdd, FALL);
  temp_power += cap_eq*deviceType->Vdd*deviceType->Vdd;


  transmitter.delay = delay;
  transmitter.power.readOp.dynamic = temp_power*2; /* since it is a diff. model*/
  transmitter.power.readOp.leakage = deviceType->Vdd *
    (4 * cmos_Isub_leakage(g_tp.min_w_nmos_, min_w_pmos, 2, nand) +
     4 * cmos_Isub_leakage(g_tp.min_w_nmos_, min_w_pmos, 1, inv));

  transmitter.power.readOp.gate_leakage = deviceType->Vdd *
    (4 * cmos_Ig_leakage(g_tp.min_w_nmos_, min_w_pmos, 2, nand) +
     4 * cmos_Ig_leakage(g_tp.min_w_nmos_, min_w_pmos, 1, inv));

  inputrise = delay / deviceType->Vth;

  /* nmos delay + wire delay */
  cap_eq = cwire + drain_C_(nsize, NCH, 1, 1, g_tp.cell_h_def)*2 +
    nsense * sense_amp_input_cap(); //+receiver cap
  /*
   * NOTE: nmos is used as both pull up and pull down transistor
   * in the transmitter. This is because for low voltage swing, drive
   * resistance of nmos is less than pmos
   * (for a detailed graph ref: On-Chip Wires: Scaling and Efficiency)
   */
  timeconst = (tr_R_on(nsize, NCH, 1)*RES_ADJ) * (cwire +
      drain_C_(nsize, NCH, 1, 1, g_tp.cell_h_def)*2) +
    rwire*cwire/2 +
    (tr_R_on(nsize, NCH, 1)*RES_ADJ + rwire) *
    nsense * sense_amp_input_cap();

  /*
   * since we are pre-equalizing and overdriving the low
   * swing wires, the net time constant is less
   * than the actual value
   */
  delay += horowitz(inputrise, timeconst, deviceType->Vth/deviceType->Vdd, .25, 0);
#define VOL_SWING .1
  temp_power += cap_eq*VOL_SWING*.400; /* .4v is the over drive voltage */
  temp_power *= 2; /* differential wire */

  l_wire.delay = delay - transmitter.delay;
  l_wire.power.readOp.dynamic = temp_power - transmitter.power.readOp.dynamic;
  l_wire.power.readOp.leakage = deviceType->Vdd*
    (4* cmos_Isub_leakage(nsize, 0, 1, nmos));

  l_wire.power.readOp.gate_leakage = deviceType->Vdd*
    (4* cmos_Ig_leakage(nsize, 0, 1, nmos));

  //double rt = horowitz(inputrise, timeconst, deviceType->Vth/deviceType->Vdd,
  //    deviceType->Vth/deviceType->Vdd, RISE)/deviceType->Vth;

  delay += g_tp.sense_delay;

  sense_amp.delay = g_tp.sense_delay;
  out_rise_time = g_tp.sense_delay/(deviceType->Vth);
  sense_amp.power.readOp.dynamic = g_tp.sense_dy_power;
  sense_amp.power.readOp.leakage = 0; //FIXME
  sense_amp.power.readOp.gate_leakage = 0;

  power.readOp.dynamic = temp_power + sense_amp.power.readOp.dynamic;
  power.readOp.leakage = transmitter.power.readOp.leakage +
                         l_wire.power.readOp.leakage +
                         sense_amp.power.readOp.leakage;
  power.readOp.gate_leakage = transmitter.power.readOp.gate_leakage +
                         l_wire.power.readOp.gate_leakage +
                         sense_amp.power.readOp.gate_leakage;
}

  double
Wire::sense_amp_input_cap()
{
  return drain_C_(g_tp.w_iso, PCH, 1, 1, g_tp.cell_h_def) +
    gate_C(g_tp.w_sense_en + g_tp.w_sense_n, 0) +
    drain_C_(g_tp.w_sense_n, NCH, 1, 1, g_tp.cell_h_def) +
    drain_C_(g_tp.w_sense_p, PCH, 1, 1, g_tp.cell_h_def);
}


void Wire::delay_optimal_wire ()
{
  double len       = wire_length;
  //double min_wire_width = wire_width; //m
  double beta = pmos_to_nmos_sz_ratio();
  double switching = 0;  // switching energy
  double short_ckt = 0;  // short-circuit energy
  double tc        = 0;  // time constant
  // input cap of min sized driver
  double input_cap = gate_C(g_tp.min_w_nmos_ + min_w_pmos, 0);

   // output parasitic capacitance of
   // the min. sized driver
  double out_cap = drain_C_(min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
    drain_C_(g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def);
  // drive resistance
  double out_res = (tr_R_on(g_tp.min_w_nmos_, NCH, 1) +
      tr_R_on(min_w_pmos, PCH, 1))/2;
  double wr = wire_res(len); //ohm

  // wire cap /m
  double wc = wire_cap(len);

  // size the repeater such that the delay of the wire is minimum
  double repeater_scaling = sqrt(out_res*wc/(wr*input_cap)); // len will cancel

   // calc the optimum spacing between the repeaters (m)

  repeater_spacing = sqrt(2 * out_res * (out_cap + input_cap)/
      ((wr/len)*(wc/len)));
  repeater_size = repeater_scaling;

  switching = (repeater_scaling * (input_cap + out_cap) +
      repeater_spacing * (wc/len)) * deviceType->Vdd * deviceType->Vdd;

  tc = out_res * (input_cap + out_cap) +
    out_res * wc/len * repeater_spacing/repeater_scaling +
    wr/len * repeater_spacing * input_cap * repeater_scaling +
    0.5 * (wr/len) * (wc/len)* repeater_spacing * repeater_spacing;

  delay = 0.693 * tc * len/repeater_spacing;

#define Ishort_ckt 65e-6 /* across all tech Ref:Banerjee et al. {IEEE TED} */
  short_ckt = deviceType->Vdd * g_tp.min_w_nmos_ * Ishort_ckt * 1.0986 *
    repeater_scaling * tc;

  area.set_area((len/repeater_spacing) *
                compute_gate_area(INV, 1, min_w_pmos * repeater_scaling,
                                          g_tp.min_w_nmos_ * repeater_scaling, g_tp.cell_h_def));
  power.readOp.dynamic = ((len/repeater_spacing)*(switching + short_ckt));
  power.readOp.leakage = ((len/repeater_spacing)*
      deviceType->Vdd*
      cmos_Isub_leakage(g_tp.min_w_nmos_*repeater_scaling, beta*g_tp.min_w_nmos_*repeater_scaling, 1, inv));
  power.readOp.gate_leakage = ((len/repeater_spacing)*
      deviceType->Vdd*
      cmos_Ig_leakage(g_tp.min_w_nmos_*repeater_scaling, beta*g_tp.min_w_nmos_*repeater_scaling, 1, inv));
}



// calculate power/delay values for wires with suboptimal repeater sizing/spacing
void
Wire::init_wire(){
  wire_length = 1;
  delay_optimal_wire();
    double sp, si;
  powerDef pow;
  si = repeater_size;
  sp = repeater_spacing;
  sp *= 1e6; // in microns

  double i, j, del;
  repeated_wire.push_back(Component());
  for (j=sp; j < 4*sp; j+=100) {
    for (i = si; i > 1; i--) {
      pow = wire_model(j*1e-6, i, &del);
      if (j == sp && i == si) {
        global.delay = del;
        global.power = pow;
        global.area.h = si;
        global.area.w = sp*1e-6; // m
      }
//      cout << "Repeater size - "<< i <<
//        " Repeater spacing - " << j <<
//        " Delay - " << del <<
//        " PowerD - " << pow.readOp.dynamic <<
//        " PowerL - " << pow.readOp.leakage <<endl;
      repeated_wire.back().delay = del;
      repeated_wire.back().power.readOp = pow.readOp;
      repeated_wire.back().area.w = j*1e-6; //m
      repeated_wire.back().area.h = i;
      repeated_wire.push_back(Component());

    }
  }
  repeated_wire.pop_back();
  update_fullswing();
  Wire *l_wire = new Wire(Low_swing, 0.001/* 1 mm*/, 1);
  low_swing.delay = l_wire->delay;
  low_swing.power = l_wire->power;
  delete l_wire;
}



void Wire::update_fullswing()
{

  list<Component>::iterator citer;
  double del[4];
  del[3] = this->global.delay + this->global.delay*.3;
  del[2] = global.delay + global.delay*.2;
  del[1] = global.delay + global.delay*.1;
  del[0] = global.delay + global.delay*.05;
  double threshold;
  double ncost;
  double cost;
  int i = 4;
  while (i>0) {
    threshold = del[i-1];
    cost = BIGNUM;
    for (citer = repeated_wire.begin(); citer != repeated_wire.end(); citer++)
    {
      if (citer->delay > threshold) {
        citer = repeated_wire.erase(citer);
        citer --;
      }
      else {
        ncost = citer->power.readOp.dynamic/global.power.readOp.dynamic +
                citer->power.readOp.leakage/global.power.readOp.leakage;
        if(ncost < cost)
        {
          cost = ncost;
          if (i == 4) {
            global_30.delay = citer->delay;
            global_30.power = citer->power;
            global_30.area  = citer->area;
          }
          else if (i==3) {
            global_20.delay = citer->delay;
            global_20.power = citer->power;
            global_20.area  = citer->area;
          }
          else if(i==2) {
            global_10.delay = citer->delay;
            global_10.power = citer->power;
            global_10.area  = citer->area;
          }
          else if(i==1) {
            global_5.delay = citer->delay;
            global_5.power = citer->power;
            global_5.area  = citer->area;
          }
        }
      }
    }
    i--;
  }
}



powerDef Wire::wire_model (double space, double size, double *delay)
{
  powerDef ptemp;
  double len = 1;
  //double min_wire_width = wire_width; //m
  double beta = pmos_to_nmos_sz_ratio();
  // switching energy
  double switching = 0;
  // short-circuit energy
  double short_ckt = 0;
  // time constant
  double tc = 0;
  // input cap of min sized driver
  double input_cap = gate_C (g_tp.min_w_nmos_ +
      min_w_pmos, 0);

   // output parasitic capacitance of
   // the min. sized driver
  double out_cap = drain_C_(min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
    drain_C_(g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def);
  // drive resistance
  double out_res = (tr_R_on(g_tp.min_w_nmos_, NCH, 1) +
      tr_R_on(min_w_pmos, PCH, 1))/2;
  double wr = wire_res(len); //ohm

  // wire cap /m
  double wc = wire_cap(len);

  repeater_spacing = space;
  repeater_size = size;

  switching = (repeater_size * (input_cap + out_cap) +
      repeater_spacing * (wc/len)) * deviceType->Vdd * deviceType->Vdd;

  tc = out_res * (input_cap + out_cap) +
    out_res * wc/len * repeater_spacing/repeater_size +
    wr/len * repeater_spacing * out_cap * repeater_size +
    0.5 * (wr/len) * (wc/len)* repeater_spacing * repeater_spacing;

  *delay = 0.693 * tc * len/repeater_spacing;

#define Ishort_ckt 65e-6 /* across all tech Ref:Banerjee et al. {IEEE TED} */
  short_ckt = deviceType->Vdd * g_tp.min_w_nmos_ * Ishort_ckt * 1.0986 *
    repeater_size * tc;

  ptemp.readOp.dynamic = ((len/repeater_spacing)*(switching + short_ckt));
  ptemp.readOp.leakage = ((len/repeater_spacing)*
      deviceType->Vdd*
      cmos_Isub_leakage(g_tp.min_w_nmos_*repeater_size, beta*g_tp.min_w_nmos_*repeater_size, 1, inv));

  ptemp.readOp.gate_leakage = ((len/repeater_spacing)*
      deviceType->Vdd*
      cmos_Ig_leakage(g_tp.min_w_nmos_*repeater_size, beta*g_tp.min_w_nmos_*repeater_size, 1, inv));

  return ptemp;
}

void
Wire::print_wire()
{

  cout << "\nWire Properties:\n\n";
  cout << "  Delay Optimal\n\tRepeater size - "<< global.area.h <<
    " \n\tRepeater spacing - " << global.area.w*1e3 << " (mm)"
    " \n\tDelay - " << global.delay*1e6 <<  " (ns/mm)"
    " \n\tPowerD - " << global.power.readOp.dynamic *1e6<< " (nJ/mm)"
    " \n\tPowerL - " << global.power.readOp.leakage << " (mW/mm)"
    " \n\tPowerLgate - " << global.power.readOp.gate_leakage << " (mW/mm)\n";
  cout << "\tWire width - " <<wire_width_init*1e6 << " microns\n";
  cout << "\tWire spacing - " <<wire_spacing_init*1e6 << " microns\n";
  cout <<endl;

  cout << "  5% Overhead\n\tRepeater size - "<< global_5.area.h <<
    " \n\tRepeater spacing - " << global_5.area.w*1e3 << " (mm)"
    " \n\tDelay - " << global_5.delay *1e6<<  " (ns/mm)"
    " \n\tPowerD - " << global_5.power.readOp.dynamic *1e6<< " (nJ/mm)"
    " \n\tPowerL - " << global_5.power.readOp.leakage << " (mW/mm)"
    " \n\tPowerLgate - " << global_5.power.readOp.gate_leakage << " (mW/mm)\n";
  cout << "\tWire width - " <<wire_width_init*1e6 << " microns\n";
  cout << "\tWire spacing - " <<wire_spacing_init*1e6 << " microns\n";
  cout <<endl;
  cout << "  10% Overhead\n\tRepeater size - "<< global_10.area.h <<
    " \n\tRepeater spacing - " << global_10.area.w*1e3 << " (mm)"
    " \n\tDelay - " << global_10.delay *1e6<<  " (ns/mm)"
    " \n\tPowerD - " << global_10.power.readOp.dynamic *1e6<< " (nJ/mm)"
    " \n\tPowerL - " << global_10.power.readOp.leakage << " (mW/mm)"
    " \n\tPowerLgate - " << global_10.power.readOp.gate_leakage << " (mW/mm)\n";
  cout << "\tWire width - " <<wire_width_init*1e6 << " microns\n";
  cout << "\tWire spacing - " <<wire_spacing_init*1e6 << " microns\n";
  cout <<endl;
  cout << "  20% Overhead\n\tRepeater size - "<< global_20.area.h <<
    " \n\tRepeater spacing - " << global_20.area.w*1e3 << " (mm)"
    " \n\tDelay - " << global_20.delay *1e6<<  " (ns/mm)"
    " \n\tPowerD - " << global_20.power.readOp.dynamic *1e6<< " (nJ/mm)"
    " \n\tPowerL - " << global_20.power.readOp.leakage << " (mW/mm)"
    " \n\tPowerLgate - " << global_20.power.readOp.gate_leakage << " (mW/mm)\n";
  cout << "\tWire width - " <<wire_width_init*1e6 << " microns\n";
  cout << "\tWire spacing - " <<wire_spacing_init*1e6 << " microns\n";
  cout <<endl;
  cout << "  30% Overhead\n\tRepeater size - "<< global_30.area.h <<
    " \n\tRepeater spacing - " << global_30.area.w*1e3 << " (mm)"
    " \n\tDelay - " << global_30.delay *1e6<<  " (ns/mm)"
    " \n\tPowerD - " << global_30.power.readOp.dynamic *1e6<< " (nJ/mm)"
    " \n\tPowerL - " << global_30.power.readOp.leakage << " (mW/mm)"
    " \n\tPowerLgate - " << global_30.power.readOp.gate_leakage << " (mW/mm)\n";
  cout << "\tWire width - " <<wire_width_init*1e6 << " microns\n";
  cout << "\tWire spacing - " <<wire_spacing_init*1e6 << " microns\n";
  cout <<endl;
  cout << "  Low-swing wire (1 mm) - Note: Unlike repeated wires, \n\tdelay and power "
            "values of low-swing wires do not\n\thave a linear relationship with length." <<
      " \n\tdelay - " << low_swing.delay *1e9<<  " (ns)"
      " \n\tpowerD - " << low_swing.power.readOp.dynamic *1e9<< " (nJ)"
      " \n\tPowerL - " << low_swing.power.readOp.leakage << " (mW)"
      " \n\tPowerLgate - " << low_swing.power.readOp.gate_leakage << " (mW)\n";
  cout << "\tWire width - " <<wire_width_init * 2 /* differential */<< " microns\n";
  cout << "\tWire spacing - " <<wire_spacing_init * 2 /* differential */<< " microns\n";
  cout <<endl;
  cout <<endl;

}