//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
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//
// G4FPEDetection
//
// Description:
//
// This global method should be used on LINUX/gcc or MacOS/clang platforms
// for activating NaN detection and FPE signals, and forcing abortion of
// the application at the time these are detected.
// Meant to be used for debug purposes, can be activated by compiling the
// "run" module with the flag G4FPE_DEBUG set in the environment.

// Author: G.Cosmo, 14 July 2010 - First version
// --------------------------------------------------------------------
#ifndef G4FPEDetection_hh
#define G4FPEDetection_hh 1

#include <iostream>
#include <stdlib.h> /* abort(), exit() */

#ifdef __linux__
#  if(defined(__GNUC__) && !defined(__clang__))
#    include <csignal>
#    include <features.h>
#    include <fenv.h>
// for G4StackBacktrace()
#    include <cxxabi.h>
#    include <execinfo.h>

struct sigaction termaction, oldaction;

static void G4StackBackTrace()
{
//   from http://linux.die.net/man/3/backtrace_symbols_fd
#    define BSIZE 50
  void* buffer[BSIZE];
  int nptrs      = backtrace(buffer, BSIZE);
  char** strings = backtrace_symbols(buffer, nptrs);
  if(strings == NULL)
  {
    perror("backtrace_symbols");
    return;
  }
  std::cerr << std::endl << "Call Stack:" << std::endl;
  for(int j = 0; j < nptrs; j++)
  {
    std::cerr << nptrs - j - 1 << ": ";
    char* mangled_start = strchr(strings[j], '(') + 1;
    if(mangled_start)
      *(mangled_start - 1) = '\0';
    char* mangled_end = strchr(mangled_start, '+');
    if(mangled_end)
      *mangled_end = '\0';
    int status     = 0;
    char* realname = 0;
    if(mangled_end && strlen(mangled_start))
      realname = abi::__cxa_demangle(mangled_start, 0, 0, &status);
    if(realname)
    {
      std::cerr << strings[j] << " : " << realname << std::endl;
      free(realname);
    }
    else
    {
      std::cerr << strings[j] << std::endl;
    }
  }
  free(strings);
  // c++filt can demangle:
  // http://gcc.gnu.org/onlinedocs/libstdc++/manual/ext_demangling.html
  //-------------------------------------------------------------------
}

static void TerminationSignalHandler(int sig, siginfo_t* sinfo,
                                     void* /* context */)
{
  std::cerr << "ERROR: " << sig;
  std::string message = "Floating-point exception (FPE).";

  if(sinfo)
  {
    switch(sinfo->si_code)
    {
#    ifdef FPE_NOOP /* BUG: MacOS uses this instead of INTDIV */
      case FPE_NOOP:
#    endif
      case FPE_INTDIV:
        message = "Integer divide by zero.";
        break;
      case FPE_INTOVF:
        message = "Integer overflow.";
        break;
      case FPE_FLTDIV:
        message = "Floating point divide by zero.";
        break;
      case FPE_FLTOVF:
        message = "Floating point overflow.";
        break;
      case FPE_FLTUND:
        message = "Floating point underflow.";
        break;
      case FPE_FLTRES:
        message = "Floating point inexact result.";
        break;
      case FPE_FLTINV:
        message = "Floating point invalid operation.";
        break;
      case FPE_FLTSUB:
        message = "Subscript out of range.";
        break;
      default:
        message = "Unknown error.";
        break;
    }
  }
  std::cerr << " - " << message << std::endl;
  G4StackBackTrace();
  ::abort();
}

static void InvalidOperationDetection()
{
  std::cout << std::endl
            << "        "
            << "############################################" << std::endl
            << "        "
            << "!!! WARNING - FPE detection is activated !!!" << std::endl
            << "        "
            << "############################################" << std::endl;

  (void) feenableexcept(FE_DIVBYZERO);
  (void) feenableexcept(FE_INVALID);
  //(void) feenableexcept( FE_OVERFLOW );
  //(void) feenableexcept( FE_UNDERFLOW );

  sigfillset(&termaction.sa_mask);
  sigdelset(&termaction.sa_mask, SIGFPE);
  termaction.sa_sigaction = TerminationSignalHandler;
  termaction.sa_flags     = SA_SIGINFO;
  sigaction(SIGFPE, &termaction, &oldaction);
}

#  else /* Not GCC */

static void InvalidOperationDetection() { ; }

#  endif

#elif defined(__MACH__) /* MacOS */

#  include <fenv.h>
#  include <signal.h>

//#define DEFINED_PPC      (defined(__ppc__) || defined(__ppc64__))
//#define DEFINED_INTEL    (defined(__i386__) || defined(__x86_64__))

#  if(defined(__ppc__) || defined(__ppc64__))  // PPC

#    define FE_EXCEPT_SHIFT 22  // shift flags right to get masks
#    define FM_ALL_EXCEPT FE_ALL_EXCEPT >> FE_EXCEPT_SHIFT

static inline int feenableexcept(unsigned int excepts)
{
  static fenv_t fenv;
  unsigned int new_excepts = (excepts & FE_ALL_EXCEPT) >> FE_EXCEPT_SHIFT,
               old_excepts;  // all previous masks

  if(fegetenv(&fenv))
  {
    return -1;
  }
  old_excepts = (fenv & FM_ALL_EXCEPT) << FE_EXCEPT_SHIFT;
  fenv        = (fenv & ~new_excepts) | new_excepts;

  return (fesetenv(&fenv) ? -1 : old_excepts);
}

static inline int fedisableexcept(unsigned int excepts)
{
  static fenv_t fenv;
  unsigned int still_on = ~((excepts & FE_ALL_EXCEPT) >> FE_EXCEPT_SHIFT),
               old_excepts;  // previous masks

  if(fegetenv(&fenv))
  {
    return -1;
  }
  old_excepts = (fenv & FM_ALL_EXCEPT) << FE_EXCEPT_SHIFT;
  fenv &= still_on;

  return (fesetenv(&fenv) ? -1 : old_excepts);
}

#  elif(defined(__i386__) || defined(__x86_64__))  // INTEL

static inline int feenableexcept(unsigned int excepts)
{
  static fenv_t fenv;
  unsigned int new_excepts = excepts & FE_ALL_EXCEPT,
               old_excepts;  // previous masks

  if(fegetenv(&fenv))
  {
    return -1;
  }
  old_excepts = fenv.__control & FE_ALL_EXCEPT;

  // unmask
  //
  fenv.__control &= ~new_excepts;
  fenv.__mxcsr &= ~(new_excepts << 7);

  return (fesetenv(&fenv) ? -1 : old_excepts);
}

static inline int fedisableexcept(unsigned int excepts)
{
  static fenv_t fenv;
  unsigned int new_excepts = excepts & FE_ALL_EXCEPT,
               old_excepts;  // all previous masks

  if(fegetenv(&fenv))
  {
    return -1;
  }
  old_excepts = fenv.__control & FE_ALL_EXCEPT;

  // mask
  //
  fenv.__control |= new_excepts;
  fenv.__mxcsr |= new_excepts << 7;

  return (fesetenv(&fenv) ? -1 : old_excepts);
}

#  elif(defined(__arm) || defined(__arm64) || defined(__aarch64__))  // Apple Silicon

#    define FE_EXCEPT_SHIFT 22  // shift flags right to get masks
#    define FM_ALL_EXCEPT FE_ALL_EXCEPT >> FE_EXCEPT_SHIFT

static inline int feenableexcept(unsigned int excepts)
{
  static fenv_t fenv;
  unsigned int new_excepts = (excepts & FE_ALL_EXCEPT) >> FE_EXCEPT_SHIFT,
               old_excepts;  // all previous masks

  if(fegetenv(&fenv))
  {
    return -1;
  }
  old_excepts = (fenv.__fpcr & FM_ALL_EXCEPT) << FE_EXCEPT_SHIFT;
  fenv.__fpcr = (fenv.__fpcr & ~new_excepts) | new_excepts;

  return (fesetenv(&fenv) ? -1 : old_excepts);
}

static inline int fedisableexcept(unsigned int excepts)
{
  static fenv_t fenv;
  unsigned int still_on = ~((excepts & FE_ALL_EXCEPT) >> FE_EXCEPT_SHIFT),
               old_excepts;  // previous masks

  if(fegetenv(&fenv))
  {
    return -1;
  }
  old_excepts = (fenv.__fpcr & FM_ALL_EXCEPT) << FE_EXCEPT_SHIFT;
  fenv.__fpcr = fenv.__fpcr | still_on;

  return (fesetenv(&fenv) ? -1 : old_excepts);
}

#  endif          /* PPC or INTEL or Apple Silicon enabling */

static void TerminationSignalHandler(int sig, siginfo_t* sinfo,
                                     void* /* context */)
{
  std::cerr << "ERROR: " << sig;
  std::string message = "Floating-point exception (FPE).";

  if(sinfo)
  {
    switch(sinfo->si_code)
    {
#  ifdef FPE_NOOP /* BUG: MacOS uses this instead of INTDIV */
      case FPE_NOOP:
#  endif
      case FPE_INTDIV:
        message = "Integer divide by zero.";
        break;
      case FPE_INTOVF:
        message = "Integer overflow.";
        break;
      case FPE_FLTDIV:
        message = "Floating point divide by zero.";
        break;
      case FPE_FLTOVF:
        message = "Floating point overflow.";
        break;
      case FPE_FLTUND:
        message = "Floating point underflow.";
        break;
      case FPE_FLTRES:
        message = "Floating point inexact result.";
        break;
      case FPE_FLTINV:
        message = "Floating point invalid operation.";
        break;
      case FPE_FLTSUB:
        message = "Subscript out of range.";
        break;
      default:
        message = "Unknown error.";
        break;
    }
  }

  std::cerr << " - " << message << std::endl;

  ::abort();
}

static void InvalidOperationDetection()
{
  struct sigaction termaction, oldaction;

  std::cout << std::endl
            << "        "
            << "############################################" << std::endl
            << "        "
            << "!!! WARNING - FPE detection is activated !!!" << std::endl
            << "        "
            << "############################################" << std::endl;

  feenableexcept(FE_DIVBYZERO);
  feenableexcept(FE_INVALID);
  // fedisableexcept( FE_OVERFLOW  );
  // fedisableexcept( FE_UNDERFLOW );

  sigfillset(&termaction.sa_mask);
  sigdelset(&termaction.sa_mask, SIGFPE);
  termaction.sa_sigaction = TerminationSignalHandler;
  termaction.sa_flags     = SA_SIGINFO;
  sigaction(SIGFPE, &termaction, &oldaction);
}

#else /* Not Linux, nor MacOS ... */

static void InvalidOperationDetection() { ; }

#endif /* Linux or MacOS */

#endif /* G4FPEDetection_hh */