import fix halt prototype code with corrections for soft exit

src/fix_halt.cpp

@@ -0,0 +1,177 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   http://lammps.sandia.gov, Sandia National Laboratories
+   Steve Plimpton, sjplimp@sandia.gov
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+#include <stdlib.h>
+#include <string.h>
+#include "fix_halt.h"
+#include "update.h"
+#include "force.h"
+#include "input.h"
+#include "modify.h"
+#include "comm.h"
+#include "timer.h"
+#include "variable.h"
+#include "error.h"
+
+using namespace LAMMPS_NS;
+using namespace FixConst;
+
+enum{BONDMAX,VARIABLE};
+enum{LT,LE,GT,GE,EQ,NEQ,XOR};
+enum{SOFT,HARD};
+
+/* ---------------------------------------------------------------------- */
+
+FixHalt::FixHalt(LAMMPS *lmp, int narg, char **arg) :
+  Fix(lmp, narg, arg), idvar(NULL)
+{
+  if (narg < 7) error->all(FLERR,"Illegal fix halt command");
+  nevery = force->inumeric(FLERR,arg[3]);
+  if (nevery <= 0) error->all(FLERR,"Illegal fix halt command");
+
+  // comparison args
+
+  idvar = NULL;
+
+  if (strcmp(arg[4],"bondmax") == 0) attribute = BONDMAX;
+  else if (strncmp(arg[4],"v_",2) == 0) {
+    attribute = VARIABLE;
+    int n = strlen(arg[4]);
+    idvar = new char[n];
+    strcpy(idvar,&arg[4][2]);
+    ivar = input->variable->find(idvar);
+    if (ivar < 0) error->all(FLERR,"Could not find fix halt variable name");
+    if (input->variable->equalstyle(ivar) == 0)
+      error->all(FLERR,"Fix halt variable is not equal-style variable");
+  } else error->all(FLERR,"Invalid fix halt attribute");
+
+  if (strcmp(arg[5],"<") == 0) operation = LT;
+  else if (strcmp(arg[5],"<=") == 0) operation = LE;
+  else if (strcmp(arg[5],">") == 0) operation = GT;
+  else if (strcmp(arg[5],">=") == 0) operation = GE;
+  else if (strcmp(arg[5],"==") == 0) operation = EQ;
+  else if (strcmp(arg[5],"!=") == 0) operation = NEQ;
+  else if (strcmp(arg[5],"|^") == 0) operation = XOR;
+  else error->all(FLERR,"Invalid fix halt operator");
+
+  value = force->numeric(FLERR,arg[6]);
+
+  // parse optional args
+
+  eflag = SOFT;
+
+  int iarg = 7;
+  while (iarg < narg) {
+    if (strcmp(arg[iarg],"error") == 0) {
+      if (iarg+2 > narg) error->all(FLERR,"Illegal fix halt command");
+      if (strcmp(arg[iarg+1],"soft") == 0) eflag = SOFT;
+      else if (strcmp(arg[iarg+1],"hard") == 0) eflag = HARD;
+      else error->all(FLERR,"Illegal fix halt command");
+      iarg += 2;
+    } else error->all(FLERR,"Illegal fix halt command");
+  }
+
+  // add nfirst to all computes that store invocation times
+  // since don't know a priori which are invoked via variables by this fix
+  // once in end_of_step() can set timestep for ones actually invoked
+
+  if (attribute == VARIABLE) {
+    const bigint nfirst = (update->ntimestep/nevery)*nevery + nevery;
+    modify->addstep_compute_all(nfirst);
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+FixHalt::~FixHalt()
+{
+  delete [] idvar;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int FixHalt::setmask()
+{
+  int mask = 0;
+  mask |= END_OF_STEP;
+  return mask;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixHalt::init()
+{
+  // set ivar from current variable list
+
+  ivar = input->variable->find(idvar);
+  if (ivar < 0) error->all(FLERR,"Could not find fix halt variable name");
+  if (input->variable->equalstyle(ivar) == 0)
+    error->all(FLERR,"Fix halt variable is not equal-style variable");
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixHalt::end_of_step()
+{
+  // make a copy of string to work on
+  // substitute for $ variables (no printing)
+  // append a newline and print final copy
+  // variable evaluation may invoke computes so wrap with clear/add
+
+  double attvalue;
+
+  if (attribute == BONDMAX) attvalue = bondmax();
+  else {
+    modify->clearstep_compute();
+    attvalue = input->variable->compute_equal(ivar);
+    modify->addstep_compute(update->ntimestep + nevery);
+  }
+
+  // check if halt is triggered, else just return
+
+  if (operation == LT) {
+    if (attvalue >= value) return;
+  } else if (operation == LE) {
+    if (attvalue > value) return;
+  } else if (operation == GT) {
+    if (attvalue <= value) return;
+  } else if (operation == GE) {
+    if (attvalue < value) return;
+  } else if (operation == EQ) {
+    if (attvalue != value) return;
+  } else if (operation == NEQ) {
+    if (attvalue == value) return;
+  } else if (operation == XOR) {
+    if ((attvalue == 0.0 && value == 0.0) || 
+        (attvalue != 0.0 && value != 0.0)) return;
+  }
+
+  // hard halt -> exit LAMMPS
+  // also print ID of fix halt in case multiple ?
+
+  if (eflag == HARD) error->all(FLERR,"Fix halt condition triggered");
+  else { // eflag == SOFT
+    if (comm->me == 0) error->message(FLERR,"Fix halt condition triggered");
+    timer->force_timeout();
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+double FixHalt::bondmax()
+{
+  // could add custom keyword methods
+  // e.g. one to compute max bond length, with no sqrt()
+
+  return 0.0;
+}

src/fix_halt.h

@@ -0,0 +1,61 @@
+/* -*- c++ -*- ----------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   http://lammps.sandia.gov, Sandia National Laboratories
+   Steve Plimpton, sjplimp@sandia.gov
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+#ifdef FIX_CLASS
+
+FixStyle(halt,FixHalt)
+
+#else
+
+#ifndef LMP_FIX_HALT_H
+#define LMP_FIX_HALT_H
+
+#include <stdio.h>
+#include "fix.h"
+
+namespace LAMMPS_NS {
+
+class FixHalt : public Fix {
+ public:
+  FixHalt(class LAMMPS *, int, char **);
+  ~FixHalt();
+  int setmask();
+  void init();
+  void end_of_step();
+
+ private:
+  int attribute,operation,eflag,ivar;
+  double attvalue,value;
+  char *idvar;
+
+  double bondmax();
+};
+
+}
+
+#endif
+#endif
+
+/* ERROR/WARNING messages:
+
+E: Illegal ... command
+
+Self-explanatory.  Check the input script syntax and compare to the
+documentation for the command.  You can use -echo screen as a
+command-line option when running LAMMPS to see the offending line.
+
+E: Cannot open fix print file %s
+
+The output file generated by the fix print command cannot be opened
+
+*/