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feenablexcept, fedisableexcept, fegetexcept



After some discussions with Ulrich, here comes a new patch to
implement handling of floating point traps in a platform independent
way for glibc.

I've only added the functions for ix86.  If this gets added to glibc
2.2., I ask the various port maintainers to send patches for their
platforms.

Andreas

1999-11-02  Andreas Jaeger  <aj@suse.de>

	* Versions.def: Add version GLIBC_2.2 for libm.

	* math/fenv.h: Add prototypes for fegetexcept, feenableexcept and
	fedisableexcept.

	* sysdeps/generic/feenablxcpt.c: Stub file.

	* sysdeps/generic/fedisblxcpt.c: Stub file.

	* sysdeps/generic/fegetexcept.c: Stub file.

	* sysdeps/i386/fpu/fedisblxcpt.c: New file.

	* sysdeps/i386/fpu/feenablxcpt.c: New file.

	* sysdeps/i386/fpu/fegetexcept.c: New file.

	* math/Makefile (libm-support): Add new files.

	* math/Versions: Add new functions with version GLIBC_2.2.

	* manual/arith.texi (Control Functions): Document fegetexcept,
	feenableexcept and fedisableexcept.

============================================================
Index: Versions.def
--- Versions.def	1999/11/01 15:53:37	1.12
+++ Versions.def	1999/11/02 08:07:30
@@ -26,6 +26,7 @@
   GLIBC_2.0
   GLIBC_2.1 GLIBC_2.0
   GLIBC_2.1.3 GLIBC_2.1
+  GLIBC_2.2 GLIBC_2.1.3
 }
 libmachuser {
   GLIBC_2.0
============================================================
Index: math/fenv.h
--- math/fenv.h	1999/10/31 23:07:49	1.7
+++ math/fenv.h	1999/11/02 08:07:30
@@ -109,6 +109,22 @@
    according to saved exceptions.  */
 extern int feupdateenv (__const fenv_t *__envp) __THROW;
 
+#ifdef __USE_GNU
+
+/* Enable individual exceptions.  Will not enable more exceptions than
+   EXCEPTS specifies.  Returns the previous enabled exceptions if all
+   exceptions are successfull set, otherwise returns -1.  */
+extern int feenableexcept (int __excepts) __THROW;
+
+/* Disable individual exceptions.  Will not disable more exceptions than
+   EXCEPTS specifies.  Returns the previous enabled exceptions if all
+   exceptions are successfull disabled, otherwise returns -1.  */
+extern int fedisableexcept (int __excepts) __THROW;
+
+/* Return enabled exceptions.  */
+extern int fegetexcept (void) __THROW;
+#endif
+
 __END_DECLS
 
 #endif /* fenv.h */
============================================================
Index: math/Makefile
--- math/Makefile	1999/11/01 02:27:37	1.90
+++ math/Makefile	1999/11/02 08:07:30
@@ -39,7 +39,8 @@
 libm-support = k_standard s_lib_version s_matherr s_signgam		\
 	       fclrexcpt fgetexcptflg fraiseexcpt fsetexcptflg		\
 	       ftestexcept fegetround fesetround fegetenv feholdexcpt	\
-	       fesetenv feupdateenv t_exp
+	       fesetenv feupdateenv t_exp fedisblxcpt feenablxcpt	\
+	       fegetexcept
 libm-calls = e_acos e_acosh e_asin e_atan2 e_atanh e_cosh e_exp e_fmod	\
 	     e_hypot e_j0 e_j1 e_jn e_lgamma_r e_log e_log10 e_pow	\
 	     e_rem_pio2 e_remainder e_scalb e_sinh e_sqrt e_gamma_r	\
============================================================
Index: math/Versions
--- math/Versions	1999/10/31 23:06:39	1.6
+++ math/Versions	1999/11/02 08:07:31
@@ -158,4 +158,8 @@
     feclearexcept; fegetenv; fegetexceptflag; feraiseexcept;
     fesetenv; fesetexceptflag; feupdateenv;
   }
+  GLIBC_2.2 {
+    # fp environment function
+    feenableexcept; fedisableexcept; fegetexcept;
+  }
 }
============================================================
Index: manual/arith.texi
--- manual/arith.texi	1999/10/31 23:05:33	1.55
+++ manual/arith.texi	1999/11/02 08:07:34
@@ -828,6 +828,42 @@
 non-zero value otherwise.
 @end deftypefun
 
+@noindent
+To control for individual exceptions if raising them causes a trap to
+occur, you can use the following two functions.
+
+@strong{Portability Note:} These functions are all GNU extensions.
+
+@comment fenv.h
+@comment GNU
+@deftypefun int feenableexcept (int @var{excepts})
+This functions enables traps for each of the exceptions as indicated by
+the parameter @var{except}.  The individual excepetions are described in
+@ref{Examining the FPU status word}.  Only the specified exceptions are
+enabled, the status of the other exceptions is not changed.
+
+The function returns the previous enabled exceptions in case the
+operation was successful, @code{-1} otherwise.
+@end deftypefun
+
+@comment fenv.h
+@comment GNU
+@deftypefun int fedisableexcept (int @var{excepts})
+This functions disables traps for each of the exceptions as indicated by
+the parameter @var{except}.  The individual excepetions are described in
+@ref{Examining the FPU status word}.  Only the specified exceptions are
+disabled, the status of the other exceptions is not changed.
+
+The function returns the previous enabled exceptions in case the
+operation was successful, @code{-1} otherwise.
+@end deftypefun
+
+@comment fenv.h
+@comment GNU
+@deftypefun int fegetexcept (int @var{excepts})
+The function returns a bitmask of all currently enabled exceptions.  It
+returns @code{-1} in case of failure.
+
 @node Arithmetic Functions
 @section Arithmetic Functions
 
============================================================
Index: sysdeps/generic/feenablxcpt.c
--- sysdeps/generic/feenablxcpt.c	created
+++ sysdeps/generic/feenablxcpt.c	Tue Nov  2 08:54:59 1999	1.1
@@ -0,0 +1,30 @@
+/* Enable floating-point exceptions.
+   Copyright (C) 1999 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Andreas Jaeger <aj@suse.de>, 1999.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <fenv.h>
+
+int
+feenableexcept (int excepts)
+{
+  /* Signal failure.  */
+  return -1;
+}
+stub_warning (feenableexcept)
+#include <stub-tag.h>
============================================================
Index: sysdeps/generic/fedisblxcpt.c
--- sysdeps/generic/fedisblxcpt.c	created
+++ sysdeps/generic/fedisblxcpt.c	Tue Nov  2 08:56:59 1999	1.1
@@ -0,0 +1,30 @@
+/* Disable floating-point exceptions.
+   Copyright (C) 1999 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Andreas Jaeger <aj@suse.de>, 1999.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <fenv.h>
+
+int
+fedisableexcept (int excepts)
+{
+  /* Signal failure.  */
+  return -1;
+}
+stub_warning (fedisableexcept)
+#include <stub-tag.h>
============================================================
Index: sysdeps/generic/fegetexcept.c
--- sysdeps/generic/fegetexcept.c	created
+++ sysdeps/generic/fegetexcept.c	Tue Nov  2 08:56:16 1999	1.1
@@ -0,0 +1,30 @@
+/* Get floating-point exceptions.
+   Copyright (C) 1999 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Andreas Jaeger <aj@suse.de>, 1999.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <fenv.h>
+
+int
+fegetexcept (void)
+{
+  /* Signal failure.  */
+  return -1;
+}
+stub_warning (fegetexcept)
+#include <stub-tag.h>
============================================================
Index: sysdeps/i386/fpu/fedisblxcpt.c
--- sysdeps/i386/fpu/fedisblxcpt.c	created
+++ sysdeps/i386/fpu/fedisblxcpt.c	Tue Nov  2 08:49:21 1999	1.1
@@ -0,0 +1,39 @@
+/* Disable floating-point exceptions.
+   Copyright (C) 1999 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Andreas Jaeger <aj@suse.de>, 1999.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <fenv.h>
+
+int
+fedisableexcept (int excepts)
+{
+  unsigned short int new_exc, old_exc;
+  
+  /* Get the current control word.  */
+  __asm__ ("fstcw %0" : "=m" (*&new_exc));
+  
+  old_exc = new_exc & FE_ALL_EXCEPT;
+
+  excepts &= FE_ALL_EXCEPT;
+  
+  new_exc &= ~excepts;
+  __asm__ ("fldcw %0" : : "m" (*&new_exc));
+
+  return old_exc;
+}
============================================================
Index: sysdeps/i386/fpu/feenablxcpt.c
--- sysdeps/i386/fpu/feenablxcpt.c	created
+++ sysdeps/i386/fpu/feenablxcpt.c	Tue Nov  2 08:47:56 1999	1.1
@@ -0,0 +1,38 @@
+/* Enable floating-point exceptions.
+   Copyright (C) 1999 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Andreas Jaeger <aj@suse.de>, 1999.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <fenv.h>
+
+int
+feenableexcept (int excepts)
+{
+  unsigned short int new_exc, old_exc;
+
+  /* Get the current control word.  */
+  __asm__ ("fstcw %0" : "=m" (*&new_exc));
+
+  excepts &= FE_ALL_EXCEPT;
+  old_exc = new_exc & FE_ALL_EXCEPT;
+
+  new_exc |= excepts;
+  __asm__ ("fldcw %0" : : "m" (*&new_exc));
+
+  return old_exc;
+}
============================================================
Index: sysdeps/i386/fpu/fegetexcept.c
--- sysdeps/i386/fpu/fegetexcept.c	created
+++ sysdeps/i386/fpu/fegetexcept.c	Tue Nov  2 08:50:41 1999	1.1
@@ -0,0 +1,32 @@
+/* Get enabled floating-point exceptions.
+   Copyright (C) 1999 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Andreas Jaeger <aj@suse.de>, 1999.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <fenv.h>
+
+int
+fegetexcept (void)
+{
+  unsigned short int exc;
+
+  /* Get the current control word.  */
+  __asm__ ("fstcw %0" : "=m" (*&exc));
+
+  return exc & FE_ALL_EXCEPT;
+}

-- 
 Andreas Jaeger   
  SuSE Labs aj@suse.de	
   private aj@arthur.rhein-neckar.de

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