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- /* ieee-utils/fp-tru64.c
- *
- * Copyright (C) 1996, 1997, 1998, 1999, 2000 Tim Mooney
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 3 of the License, or (at
- * your option) any later version.
- *
- * This program 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
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- */
- /*
- * Under Compaq's Unix with the silly name, read the man pages for read_rnd,
- * write_rnd, and ieee(3) for more information on the functions used here.
- *
- * Note that enabling control of dynamic rounding mode (via write_rnd) requires
- * that you pass a special flag to your C compiler. For Compaq's C compiler
- * the flag is `-fprm d', for gcc it's `-mfp-rounding-mode=d'.
- *
- * Enabling the trap control (via ieee_set_fp_control) also requires a
- * flag be passed to the C compiler. The flag for Compaq's C compiler
- * is `-ieee' and for gcc it's `-mieee'.
- * We have not implemented the `inexact' case, since it is rarely used
- * and requires the library being built with an additional compiler
- * flag that can degrade performance for everything else. If you need
- * to add support for `inexact' the relevant flag for Compaq's
- * compiler is `-ieee_with_inexact', and the flag for gcc is
- * `-mieee-with-inexact'.
- *
- * Problem have been reported with the "fixed" float.h installed with
- * gcc-2.95 lacking some of the definitions in the system float.h (the
- * symptoms are errors like: `FP_RND_RN' undeclared). To work around
- * this we can include the system float.h before the gcc version, e.g.
- *
- * #include "/usr/include/float.h"
- * #include <float.h>
- */
- #include <float.h>
- #ifndef FP_RND_RN
- # undef _FLOAT_H_
- # include /usr/include/float.h
- # undef _FLOAT_H_
- # include <float.h>
- #endif
- #include <machine/fpu.h>
- #include <stdio.h>
- #include "gsl_ieee_utils.h"
- #include "gsl_errno.h"
- int
- gsl_ieee_set_mode (int precision, int rounding, int exception_mask)
- {
- unsigned long int mode = 0 ;
- unsigned int rnd = 0 ;
- /* I'm actually not completely sure that the alpha only supports default
- * precisions rounding, but I couldn't find any information regarding this, so
- * it seems safe to assume this for now until it's proven otherwise.
- */
- switch (precision)
- {
- case GSL_IEEE_SINGLE_PRECISION:
- GSL_ERROR ("Tru64 Unix on the alpha only supports default precision rounding",
- GSL_EUNSUP) ;
- break ;
- case GSL_IEEE_DOUBLE_PRECISION:
- GSL_ERROR ("Tru64 Unix on the alpha only supports default precision rounding",
- GSL_EUNSUP) ;
- break ;
- case GSL_IEEE_EXTENDED_PRECISION:
- GSL_ERROR ("Tru64 Unix on the alpha only supports default precision rounding",
- GSL_EUNSUP) ;
- break ;
- }
- switch (rounding)
- {
- case GSL_IEEE_ROUND_TO_NEAREST:
- rnd = FP_RND_RN ;
- write_rnd (rnd) ;
- break ;
- case GSL_IEEE_ROUND_DOWN:
- rnd = FP_RND_RM ;
- write_rnd (rnd) ;
- break ;
- case GSL_IEEE_ROUND_UP:
- rnd = FP_RND_RP ;
- write_rnd (rnd) ;
- break ;
- case GSL_IEEE_ROUND_TO_ZERO:
- rnd = FP_RND_RZ ;
- write_rnd (rnd) ;
- break ;
- default:
- rnd = FP_RND_RN ;
- write_rnd (rnd) ;
- }
- /* Turn on all the exceptions apart from 'inexact' */
- /* from the ieee(3) man page:
- * IEEE_TRAP_ENABLE_INV -> Invalid operation
- * IEEE_TRAP_ENABLE_DZE -> Divide by 0
- * IEEE_TRAP_ENABLE_OVF -> Overflow
- * IEEE_TRAP_ENABLE_UNF -> Underflow
- * IEEE_TRAP_ENABLE_INE -> Inexact (requires special option to C compiler)
- * IEEE_TRAP_ENABLE_DNO -> denormal operand
- * Note: IEEE_TRAP_ENABLE_DNO is not supported on OSF 3.x or Digital Unix
- * 4.0 - 4.0d(?).
- * IEEE_TRAP_ENABLE_MASK -> mask of all the trap enables
- * IEEE_MAP_DMZ -> map denormal inputs to zero
- * IEEE_MAP_UMZ -> map underflow results to zero
- */
- mode = IEEE_TRAP_ENABLE_INV | IEEE_TRAP_ENABLE_DZE | IEEE_TRAP_ENABLE_OVF
- | IEEE_TRAP_ENABLE_UNF ;
- if (exception_mask & GSL_IEEE_MASK_INVALID)
- mode &= ~ IEEE_TRAP_ENABLE_INV ;
- if (exception_mask & GSL_IEEE_MASK_DENORMALIZED)
- {
- #ifdef IEEE_TRAP_ENABLE_DNO
- mode &= ~ IEEE_TRAP_ENABLE_DNO ;
- #else
- GSL_ERROR ("Sorry, this version of Digital Unix does not support denormalized operands", GSL_EUNSUP) ;
- #endif
- }
- if (exception_mask & GSL_IEEE_MASK_DIVISION_BY_ZERO)
- mode &= ~ IEEE_TRAP_ENABLE_DZE ;
- if (exception_mask & GSL_IEEE_MASK_OVERFLOW)
- mode &= ~ IEEE_TRAP_ENABLE_OVF ;
- if (exception_mask & GSL_IEEE_MASK_UNDERFLOW)
- mode &= ~ IEEE_TRAP_ENABLE_UNF ;
- if (exception_mask & GSL_IEEE_TRAP_INEXACT)
- {
- /* To implement this would require a special flag to the C
- compiler which can cause degraded performance */
- GSL_ERROR ("Sorry, GSL does not implement trap-inexact for Tru64 Unix on the alpha - see fp-tru64.c for details", GSL_EUNSUP) ;
- /* In case you need to add it, the appropriate line would be
- *
- * mode |= IEEE_TRAP_ENABLE_INE ;
- *
- */
- }
- else
- {
- mode &= ~ IEEE_TRAP_ENABLE_INE ;
- }
- ieee_set_fp_control (mode) ;
- return GSL_SUCCESS ;
- }
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