cpython-withatomic / Modules / fpectlmodule.c

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    /                       Copyright (c) 1996.                           \ 
   |          The Regents of the University of California.                 |
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		  Floating point exception control module.

   This Python module provides bare-bones control over floating point
   units from several hardware manufacturers.  Specifically, it allows
   the user to turn on the generation of SIGFPE whenever any of the
   three serious IEEE 754 exceptions (Division by Zero, Overflow,
   Invalid Operation) occurs.  We currently ignore Underflow and
   Inexact Result exceptions, although those could certainly be added
   if desired.

   The module also establishes a signal handler for SIGFPE during
   initialization.  This builds on code found in the Python
   distribution at Include/pyfpe.h and Python/pyfpe.c.  If those files
   are not in your Python distribution, find them in a patch at

   This module is only useful to you if it happens to include code
   specific for your hardware and software environment.  If you can
   contribute OS-specific code for new platforms, or corrections for
   the code provided, it will be greatly appreciated.

   ** Version 1.0: September 20, 1996.  Lee Busby, LLNL.

#ifdef __cplusplus
extern "C" {

#include "Python.h"
#include <signal.h>

/* Define locally if they are not defined in Python.  This gives only
 * the limited control to induce a core dump in case of an exception.
#include <setjmp.h>
static jmp_buf PyFPE_jbuf;
static int PyFPE_counter = 0;

typedef RETSIGTYPE Sigfunc(int);
static Sigfunc sigfpe_handler;
static void fpe_reset(Sigfunc *);

static PyObject *fpe_error;
DL_EXPORT(void) initfpectl(void);
static PyObject *turnon_sigfpe            (PyObject *self,PyObject *args);
static PyObject *turnoff_sigfpe           (PyObject *self,PyObject *args);

static PyMethodDef fpectl_methods[] = {
    {"turnon_sigfpe",		 (PyCFunction) turnon_sigfpe,		 1},
    {"turnoff_sigfpe",		 (PyCFunction) turnoff_sigfpe, 	         1},

static PyObject *turnon_sigfpe(PyObject *self,PyObject *args)
    /* Do any architecture-specific one-time only initialization here. */

    Py_INCREF (Py_None);
    return Py_None;

static void fpe_reset(Sigfunc *handler)
    /* Reset the exception handling machinery, and reset the signal
     * handler for SIGFPE to the given handler.

/*-- IRIX -----------------------------------------------------------------*/
#if defined(sgi)
    /* See man page on handle_sigfpes -- must link with -lfpe
     * My usage doesn't follow the man page exactly.  Maybe somebody
     * else can explain handle_sigfpes to me....
     * cc -c -I/usr/local/python/include fpectlmodule.c
     * ld -shared -o fpectlmodule.o -lfpe 
#include <sigfpe.h>
    typedef void user_routine (unsigned[5], int[2]);
    typedef void abort_routine (unsigned long);
    handle_sigfpes(_OFF, 0,
		 (user_routine *)0,
    handle_sigfpes(_ON, _EN_OVERFL | _EN_DIVZERO | _EN_INVALID,
		 (user_routine *)0,
    signal(SIGFPE, handler);

/*-- SunOS and Solaris ----------------------------------------------------*/
#elif defined(sun)
    /* References: ieee_handler, ieee_sun, ieee_functions, and ieee_flags
       man pages (SunOS or Solaris)
       cc -c -I/usr/local/python/include fpectlmodule.c
       ld -G -o -L/opt/SUNWspro/lib fpectlmodule.o -lsunmath -lm
#include <math.h>
    char *mode="exception", *in="all", *out;
    (void) nonstandard_arithmetic();
    (void) ieee_flags("clearall",mode,in,&out);
    (void) ieee_handler("set","common",(sigfpe_handler_type)handler);
    signal(SIGFPE, handler);

/*-- HPUX -----------------------------------------------------------------*/
#elif defined(__hppa) || defined(hppa)
    /* References:   fpsetmask man page */
    /* cc -Aa +z -c -I/usr/local/python/include fpectlmodule.c */
    /* ld -b -o fpectlmodule.o -lm */
#include <math.h>
    signal(SIGFPE, handler);

/*-- IBM AIX --------------------------------------------------------------*/
#elif defined(__AIX) || defined(_AIX)
    /* References:   fp_trap, fp_enable man pages */
#include <fptrap.h>
    signal(SIGFPE, handler);

/*-- DEC ALPHA OSF --------------------------------------------------------*/
#elif defined(__alpha)
    /* References:   exception_intro, ieee man pages */
    /* cc -c -I/usr/local/python/include fpectlmodule.c */
    /* ld -shared -o fpectlmodule.o */
#include <machine/fpu.h>
    unsigned long fp_control =
    signal(SIGFPE, handler);

/*-- Cray Unicos ----------------------------------------------------------*/
#elif defined(cray)
    /* UNICOS delivers SIGFPE by default, but no matherr */
    signal(SIGFPE, handler);

/*-- Linux ----------------------------------------------------------------*/
#elif defined(linux)
#ifdef __GLIBC__
#include <fpu_control.h>
#include <i386/fpu_control.h>
    signal(SIGFPE, handler);

/*-- NeXT -----------------------------------------------------------------*/
#elif defined(NeXT) && defined(m68k) && defined(__GNUC__)
    /* NeXT needs explicit csr set to generate SIGFPE */
    asm("fmovel     #0x1400,fpcr");   /* set OVFL and ZD bits */
    signal(SIGFPE, handler);

/*-- Microsoft Windows, NT ------------------------------------------------*/
#elif defined(_MSC_VER)
    /* Reference: Visual C++ Books Online 4.2,
       Run-Time Library Reference, _control87, _controlfp */
#include <float.h>
    unsigned int cw = _EM_INVALID | _EM_ZERODIVIDE | _EM_OVERFLOW;
    (void)_controlfp(0, cw);
    signal(SIGFPE, handler);

/*-- Give Up --------------------------------------------------------------*/
    fputs("Operation not implemented\n", stderr);


static PyObject *turnoff_sigfpe(PyObject *self,PyObject *args)
    fputs("Operation not implemented\n", stderr);
    Py_INCREF (Py_None);
    return Py_None;

static void sigfpe_handler(int signo)
    if(PyFPE_counter) {
        longjmp(PyFPE_jbuf, 1);
    } else {
        Py_FatalError("Unprotected floating point exception");

DL_EXPORT(void) initfpectl(void)
    PyObject *m, *d;
    m = Py_InitModule("fpectl", fpectl_methods);
    d = PyModule_GetDict(m);
    fpe_error = PyErr_NewException("fpectl.error", NULL, NULL);
    if (fpe_error != NULL)
	PyDict_SetItemString(d, "error", fpe_error);

#ifdef __cplusplus