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 #if defined(__FreeBSD__)
  72 #  include <ieeefp.h>
  73 #endif
  74
  75 #ifndef WANT_SIGFPE_HANDLER
  76 /* Define locally if they are not defined in Python.  This gives only
  77  * the limited control to induce a core dump in case of an exception.
  78  */
  79 #include <setjmp.h>
  80 static jmp_buf PyFPE_jbuf;
  81 static int PyFPE_counter = 0;
  82 #endif
  83
  84 typedef void Sigfunc(int);
  85 static Sigfunc sigfpe_handler;
  86 static void fpe_reset(Sigfunc *);
  87
  88 static PyObject *fpe_error;
  89 PyMODINIT_FUNC initfpectl(void);
  90 static PyObject *turnon_sigfpe            (PyObject *self,PyObject *args);
  91 static PyObject *turnoff_sigfpe           (PyObject *self,PyObject *args);
  92
  93 static PyMethodDef fpectl_methods[] = {
  94     {"turnon_sigfpe",            (PyCFunction) turnon_sigfpe,            METH_VARARGS},
  95     {"turnoff_sigfpe",           (PyCFunction) turnoff_sigfpe,           METH_VARARGS},
  96     {0,0}
  97 };
  98
  99 static PyObject *turnon_sigfpe(PyObject *self,PyObject *args)
 100 {
 101     /* Do any architecture-specific one-time only initialization here. */
 102
 103     fpe_reset(sigfpe_handler);
 104     Py_INCREF (Py_None);
 105     return Py_None;
 106 }
 107
 108 static void fpe_reset(Sigfunc *handler)
 109 {
 110     /* Reset the exception handling machinery, and reset the signal
 111      * handler for SIGFPE to the given handler.
 112      */
 113
 114 /*-- IRIX -----------------------------------------------------------------*/
 115 #if defined(sgi)
 116     /* See man page on handle_sigfpes -- must link with -lfpe
 117      * My usage doesn't follow the man page exactly.  Maybe somebody
 118      * else can explain handle_sigfpes to me....
 119      * cc -c -I/usr/local/python/include fpectlmodule.c
 120      * ld -shared -o fpectlmodule.so fpectlmodule.o -lfpe
 121      */
 122 #include <sigfpe.h>
 123     typedef void user_routine (unsigned[5], int[2]);
 124     typedef void abort_routine (unsigned long);
 125     handle_sigfpes(_OFF, 0,
 126                  (user_routine *)0,
 127                  _TURN_OFF_HANDLER_ON_ERROR,
 128                  NULL);
 129     handle_sigfpes(_ON, _EN_OVERFL | _EN_DIVZERO | _EN_INVALID,
 130                  (user_routine *)0,
 131                  _ABORT_ON_ERROR,
 132                  NULL);
 133     PyOS_setsig(SIGFPE, handler);
 134
 135 /*-- SunOS and Solaris ----------------------------------------------------*/
 136 #elif defined(sun)
 137     /* References: ieee_handler, ieee_sun, ieee_functions, and ieee_flags
 138        man pages (SunOS or Solaris)
 139        cc -c -I/usr/local/python/include fpectlmodule.c
 140        ld -G -o fpectlmodule.so -L/opt/SUNWspro/lib fpectlmodule.o -lsunmath -lm
 141      */
 142 #include <math.h>
 143 #ifndef _SUNMATH_H
 144     extern void nonstandard_arithmetic(void);
 145     extern int ieee_flags(const char*, const char*, const char*, char **);
 146     extern long ieee_handler(const char*, const char*, sigfpe_handler_type);
 147 #endif
 148
 149     char *mode="exception", *in="all", *out;
 150     (void) nonstandard_arithmetic();
 151     (void) ieee_flags("clearall",mode,in,&out);
 152     (void) ieee_handler("set","common",(sigfpe_handler_type)handler);
 153     PyOS_setsig(SIGFPE, handler);
 154
 155 /*-- HPUX -----------------------------------------------------------------*/
 156 #elif defined(__hppa) || defined(hppa)
 157     /* References:   fpsetmask man page */
 158     /* cc -Aa +z -c -I/usr/local/python/include fpectlmodule.c */
 159     /* ld -b -o fpectlmodule.sl fpectlmodule.o -lm */
 160 #include <math.h>
 161     fpsetdefaults();
 162     PyOS_setsig(SIGFPE, handler);
 163
 164 /*-- IBM AIX --------------------------------------------------------------*/
 165 #elif defined(__AIX) || defined(_AIX)
 166     /* References:   fp_trap, fp_enable man pages */
 167 #include <fptrap.h>
 168     fp_trap(FP_TRAP_SYNC);
 169     fp_enable(TRP_INVALID | TRP_DIV_BY_ZERO | TRP_OVERFLOW);
 170     PyOS_setsig(SIGFPE, handler);
 171
 172 /*-- DEC ALPHA OSF --------------------------------------------------------*/
 173 #elif defined(__alpha) && defined(__osf__)
 174     /* References:   exception_intro, ieee man pages */
 175     /* cc -c -I/usr/local/python/include fpectlmodule.c */
 176     /* ld -shared -o fpectlmodule.so fpectlmodule.o */
 177 #include <machine/fpu.h>
 178     unsigned long fp_control =
 179     IEEE_TRAP_ENABLE_INV | IEEE_TRAP_ENABLE_DZE | IEEE_TRAP_ENABLE_OVF;
 180     ieee_set_fp_control(fp_control);
 181     PyOS_setsig(SIGFPE, handler);
 182
 183 /*-- DEC ALPHA LINUX ------------------------------------------------------*/
 184 #elif defined(__alpha) && defined(linux)
 185 #include <asm/fpu.h>
 186     unsigned long fp_control =
 187     IEEE_TRAP_ENABLE_INV | IEEE_TRAP_ENABLE_DZE | IEEE_TRAP_ENABLE_OVF;
 188     ieee_set_fp_control(fp_control);
 189     PyOS_setsig(SIGFPE, handler);
 190
 191 /*-- DEC ALPHA VMS --------------------------------------------------------*/
 192 #elif defined(__ALPHA) && defined(__VMS)
 193     PyOS_setsig(SIGFPE, handler);
 194
 195 /*-- Cray Unicos ----------------------------------------------------------*/
 196 #elif defined(cray)
 197     /* UNICOS delivers SIGFPE by default, but no matherr */
 198 #ifdef HAS_LIBMSET
 199     libmset(-1);
 200 #endif
 201     PyOS_setsig(SIGFPE, handler);
 202
 203 /*-- FreeBSD ----------------------------------------------------------------*/
 204 #elif defined(__FreeBSD__)
 205     fpresetsticky(fpgetsticky());
 206     fpsetmask(FP_X_INV | FP_X_DZ | FP_X_OFL);
 207     PyOS_setsig(SIGFPE, handler);
 208
 209 /*-- Linux ----------------------------------------------------------------*/
 210 #elif defined(linux)
 211 #ifdef __GLIBC__
 212 #include <fpu_control.h>
 213 #else
 214 #include <i386/fpu_control.h>
 215 #endif
 216 #ifdef _FPU_SETCW
 217     {
 218         fpu_control_t cw = 0x1372;
 219         _FPU_SETCW(cw);
 220     }
 221 #else
 222     __setfpucw(0x1372);
 223 #endif
 224     PyOS_setsig(SIGFPE, handler);
 225
 226 /*-- Microsoft Windows, NT ------------------------------------------------*/
 227 #elif defined(_MSC_VER)
 228     /* Reference: Visual C++ Books Online 4.2,
 229        Run-Time Library Reference, _control87, _controlfp */
 230 #include <float.h>
 231     unsigned int cw = _EM_INVALID | _EM_ZERODIVIDE | _EM_OVERFLOW;
 232     (void)_controlfp(0, cw);
 233     PyOS_setsig(SIGFPE, handler);
 234
 235 /*-- Give Up --------------------------------------------------------------*/
 236 #else
 237     fputs("Operation not implemented\n", stderr);
 238 #endif
 239
 240 }
 241
 242 static PyObject *turnoff_sigfpe(PyObject *self,PyObject *args)
 243 {
 244 #ifdef __FreeBSD__
 245     fpresetsticky(fpgetsticky());
 246     fpsetmask(0);
 247 #else
 248     fputs("Operation not implemented\n", stderr);
 249 #endif
 250     Py_INCREF(Py_None);
 251     return Py_None;
 252 }
 253
 254 static void sigfpe_handler(int signo)
 255 {
 256     fpe_reset(sigfpe_handler);
 257     if(PyFPE_counter) {
 258         longjmp(PyFPE_jbuf, 1);
 259     } else {
 260         Py_FatalError("Unprotected floating point exception");
 261     }
 262 }
 263
 264 PyMODINIT_FUNC initfpectl(void)
 265 {
 266     PyObject *m, *d;
 267     m = Py_InitModule("fpectl", fpectl_methods);
 268     d = PyModule_GetDict(m);
 269     fpe_error = PyErr_NewException("fpectl.error", NULL, NULL);
 270     if (fpe_error != NULL)
 271         PyDict_SetItemString(d, "error", fpe_error);
 272 }
 273
 274 #ifdef __cplusplus
 275 }
 276 #endif