Modules/fpectlmodule.c

   1 /*
   2      ---------------------------------------------------------------------
   3     /                       Copyright (c) 1996.                           \
   4    |          The Regents of the University of California.                 |
   5    |                        All rights reserved.                           |
   6    |                                                                       |
   7    |   Permission to use, copy, modify, and distribute this software for   |
   8    |   any purpose without fee is hereby granted, provided that this en-   |
   9    |   tire notice is included in all copies of any software which is or   |
  10    |   includes  a  copy  or  modification  of  this software and in all   |
  11    |   copies of the supporting documentation for such software.           |
  12    |                                                                       |
  13    |   This  work was produced at the University of California, Lawrence   |
  14    |   Livermore National Laboratory under  contract  no.  W-7405-ENG-48   |
  15    |   between  the  U.S.  Department  of  Energy and The Regents of the   |
  16    |   University of California for the operation of UC LLNL.              |
  17    |                                                                       |
  18    |                              DISCLAIMER                               |
  19    |                                                                       |
  20    |   This  software was prepared as an account of work sponsored by an   |
  21    |   agency of the United States Government. Neither the United States   |
  22    |   Government  nor the University of California nor any of their em-   |
  23    |   ployees, makes any warranty, express or implied, or  assumes  any   |
  24    |   liability  or  responsibility  for the accuracy, completeness, or   |
  25    |   usefulness of any information,  apparatus,  product,  or  process   |
  26    |   disclosed,   or  represents  that  its  use  would  not  infringe   |
  27    |   privately-owned rights. Reference herein to any specific  commer-   |
  28    |   cial  products,  process,  or  service  by trade name, trademark,   |
  29    |   manufacturer, or otherwise, does not  necessarily  constitute  or   |
  30    |   imply  its endorsement, recommendation, or favoring by the United   |
  31    |   States Government or the University of California. The views  and   |
  32    |   opinions  of authors expressed herein do not necessarily state or   |
  33    |   reflect those of the United States Government or  the  University   |
  34    |   of  California,  and shall not be used for advertising or product   |
  35     \  endorsement purposes.                                              /
  36      ---------------------------------------------------------------------
  37 */
  38
  39 /*
  40                   Floating point exception control module.
  41
  42    This Python module provides bare-bones control over floating point
  43    units from several hardware manufacturers.  Specifically, it allows
  44    the user to turn on the generation of SIGFPE whenever any of the
  45    three serious IEEE 754 exceptions (Division by Zero, Overflow,
  46    Invalid Operation) occurs.  We currently ignore Underflow and
  47    Inexact Result exceptions, although those could certainly be added
  48    if desired.
  49
  50    The module also establishes a signal handler for SIGFPE during
  51    initialization.  This builds on code found in the Python
  52    distribution at Include/pyfpe.h and Python/pyfpe.c.  If those files
  53    are not in your Python distribution, find them in a patch at
  54    ftp://icf.llnl.gov/pub/python/busby/patches.961108.tgz.
  55
  56    This module is only useful to you if it happens to include code
  57    specific for your hardware and software environment.  If you can
  58    contribute OS-specific code for new platforms, or corrections for
  59    the code provided, it will be greatly appreciated.
  60
  61    ** Version 1.0: September 20, 1996.  Lee Busby, LLNL.
  62  */
  63
  64 #ifdef __cplusplus
  65 extern "C" {
  66 #endif
  67
  68 #include "Python.h"
  69 #include <signal.h>
  70
  71 #ifndef WANT_SIGFPE_HANDLER
  72 /* Define locally if they are not defined in Python.  This gives only
  73  * the limited control to induce a core dump in case of an exception.
  74  */
  75 #include <setjmp.h>
  76 static jmp_buf PyFPE_jbuf;
  77 static int PyFPE_counter = 0;
  78 #endif
  79
  80 typedef RETSIGTYPE Sigfunc(int);
  81 static Sigfunc sigfpe_handler;
  82 static void fpe_reset(Sigfunc *);
  83
  84 static PyObject *fpe_error;
  85 void initfpectl(void);
  86 static PyObject *turnon_sigfpe            (PyObject *self,PyObject *args);
  87 static PyObject *turnoff_sigfpe           (PyObject *self,PyObject *args);
  88
  89 static PyMethodDef fpectl_methods[] = {
  90     {"turnon_sigfpe",            (PyCFunction) turnon_sigfpe,            1},
  91     {"turnoff_sigfpe",           (PyCFunction) turnoff_sigfpe,           1},
  92     {0,0}
  93 };
  94
  95 static PyObject *turnon_sigfpe(PyObject *self,PyObject *args)
  96 {
  97     /* Do any architecture-specific one-time only initialization here. */
  98
  99     fpe_reset(sigfpe_handler);
 100     Py_INCREF (Py_None);
 101     return Py_None;
 102 }
 103
 104 static void fpe_reset(Sigfunc *handler)
 105 {
 106     /* Reset the exception handling machinery, and reset the signal
 107      * handler for SIGFPE to the given handler.
 108      */
 109
 110 /*-- IRIX -----------------------------------------------------------------*/
 111 #if defined(sgi)
 112     /* See man page on handle_sigfpes -- must link with -lfpe
 113      * My usage doesn't follow the man page exactly.  Maybe somebody
 114      * else can explain handle_sigfpes to me....
 115      * cc -c -I/usr/local/python/include fpectlmodule.c
 116      * ld -shared -o fpectlmodule.so fpectlmodule.o -lfpe
 117      */
 118 #include <sigfpe.h>
 119     typedef void user_routine (unsigned[5], int[2]);
 120     typedef void abort_routine (unsigned long);
 121     handle_sigfpes(_OFF, 0,
 122                  (user_routine *)0,
 123                  _TURN_OFF_HANDLER_ON_ERROR,
 124                  NULL);
 125     handle_sigfpes(_ON, _EN_OVERFL | _EN_DIVZERO | _EN_INVALID,
 126                  (user_routine *)0,
 127                  _ABORT_ON_ERROR,
 128                  NULL);
 129     signal(SIGFPE, handler);
 130
 131 /*-- SunOS and Solaris ----------------------------------------------------*/
 132 #elif defined(sun)
 133     /* References: ieee_handler, ieee_sun, ieee_functions, and ieee_flags
 134        man pages (SunOS or Solaris)
 135        cc -c -I/usr/local/python/include fpectlmodule.c
 136        ld -G -o fpectlmodule.so -L/opt/SUNWspro/lib fpectlmodule.o -lsunmath -lm
 137      */
 138 #include <math.h>
 139     char *mode="exception", *in="all", *out;
 140     (void) nonstandard_arithmetic();
 141     (void) ieee_flags("clearall",mode,in,&out);
 142     (void) ieee_handler("set","common",(sigfpe_handler_type)handler);
 143     signal(SIGFPE, handler);
 144
 145 /*-- HPUX -----------------------------------------------------------------*/
 146 #elif defined(__hppa) || defined(hppa)
 147     /* References:   fpsetmask man page */
 148     /* cc -Aa +z -c -I/usr/local/python/include fpectlmodule.c */
 149     /* ld -b -o fpectlmodule.sl fpectlmodule.o -lm */
 150 #include <math.h>
 151     fpsetdefaults();
 152     signal(SIGFPE, handler);
 153
 154 /*-- IBM AIX --------------------------------------------------------------*/
 155 #elif defined(__AIX) || defined(_AIX)
 156     /* References:   fp_trap, fp_enable man pages */
 157 #include <fptrap.h>
 158     fp_trap(FP_TRAP_SYNC);
 159     fp_enable(TRP_INVALID | TRP_DIV_BY_ZERO | TRP_OVERFLOW);
 160     signal(SIGFPE, handler);
 161
 162 /*-- DEC ALPHA OSF --------------------------------------------------------*/
 163 #elif defined(__alpha)
 164     /* References:   exception_intro, ieee man pages */
 165     /* cc -c -I/usr/local/python/include fpectlmodule.c */
 166     /* ld -shared -o fpectlmodule.so fpectlmodule.o */
 167 #include <machine/fpu.h>
 168     unsigned long fp_control =
 169     IEEE_TRAP_ENABLE_INV | IEEE_TRAP_ENABLE_DZE | IEEE_TRAP_ENABLE_OVF;
 170     ieee_set_fp_control(fp_control);
 171     signal(SIGFPE, handler);
 172
 173 /*-- Cray Unicos ----------------------------------------------------------*/
 174 #elif defined(cray)
 175     /* UNICOS delivers SIGFPE by default, but no matherr */
 176 #ifdef HAS_LIBMSET
 177     libmset(-1);
 178 #endif
 179     signal(SIGFPE, handler);
 180
 181 /*-- Linux ----------------------------------------------------------------*/
 182 #elif defined(linux)
 183 #ifdef __GLIBC__
 184 #include <fpu_control.h>
 185 #else
 186 #include <i386/fpu_control.h>
 187 #endif
 188     __setfpucw(0x1372);
 189     signal(SIGFPE, handler);
 190
 191 /*-- NeXT -----------------------------------------------------------------*/
 192 #elif defined(NeXT) && defined(m68k) && defined(__GNUC__)
 193     /* NeXT needs explicit csr set to generate SIGFPE */
 194     asm("fmovel     #0x1400,fpcr");   /* set OVFL and ZD bits */
 195     signal(SIGFPE, handler);
 196
 197 /*-- Microsoft Windows, NT ------------------------------------------------*/
 198 #elif defined(_MSC_VER)
 199     /* Reference: Visual C++ Books Online 4.2,
 200        Run-Time Library Reference, _control87, _controlfp */
 201 #include <float.h>
 202     unsigned int cw = _EM_INVALID | _EM_ZERODIVIDE | _EM_OVERFLOW;
 203     (void)_controlfp(0, cw);
 204     signal(SIGFPE, handler);
 205
 206 /*-- Give Up --------------------------------------------------------------*/
 207 #else
 208     fputs("Operation not implemented\n", stderr);
 209 #endif
 210
 211 }
 212
 213 static PyObject *turnoff_sigfpe(PyObject *self,PyObject *args)
 214 {
 215     fputs("Operation not implemented\n", stderr);
 216     Py_INCREF (Py_None);
 217     return Py_None;
 218 }
 219
 220 static void sigfpe_handler(int signo)
 221 {
 222     fpe_reset(sigfpe_handler);
 223     if(PyFPE_counter) {
 224         longjmp(PyFPE_jbuf, 1);
 225     } else {
 226         Py_FatalError("Unprotected floating point exception");
 227     }
 228 }
 229
 230 void initfpectl(void)
 231 {
 232     PyObject *m, *d;
 233     m = Py_InitModule("fpectl", fpectl_methods);
 234     d = PyModule_GetDict(m);
 235     fpe_error = PyErr_NewException("fpectl.error", NULL, NULL);
 236     if (fpe_error != NULL)
 237         PyDict_SetItemString(d, "error", fpe_error);
 238 }
 239
 240 #ifdef __cplusplus
 241 }
 242 #endif