1 /* ieee-utils/fp-tru64.c 2 * 3 * Copyright (C) 1996, 1997, 1998, 1999, 2000 Tim Mooney 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 3 of the License, or (at 8 * your option) any later version. 9 * 10 * This program is distributed in the hope that it will be useful, but 11 * WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 * General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, write to the Free Software 17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. 18 */ 19 20 21 /* 22 * Under Compaq's Unix with the silly name, read the man pages for read_rnd, 23 * write_rnd, and ieee(3) for more information on the functions used here. 24 * 25 * Note that enabling control of dynamic rounding mode (via write_rnd) requires 26 * that you pass a special flag to your C compiler. For Compaq's C compiler 27 * the flag is `-fprm d', for gcc it's `-mfp-rounding-mode=d'. 28 * 29 * Enabling the trap control (via ieee_set_fp_control) also requires a 30 * flag be passed to the C compiler. The flag for Compaq's C compiler 31 * is `-ieee' and for gcc it's `-mieee'. 32 33 * We have not implemented the `inexact' case, since it is rarely used 34 * and requires the library being built with an additional compiler 35 * flag that can degrade performance for everything else. If you need 36 * to add support for `inexact' the relevant flag for Compaq's 37 * compiler is `-ieee_with_inexact', and the flag for gcc is 38 * `-mieee-with-inexact'. 39 * 40 * Problem have been reported with the "fixed" float.h installed with 41 * gcc-2.95 lacking some of the definitions in the system float.h (the 42 * symptoms are errors like: `FP_RND_RN' undeclared). To work around 43 * this we can include the system float.h before the gcc version, e.g. 44 * 45 * #include "/usr/include/float.h" 46 * #include <float.h> 47 */ 48 49 #include <float.h> 50 51 #ifndef FP_RND_RN 52 # undef _FLOAT_H_ 53 # include /usr/include/float.h 54 # undef _FLOAT_H_ 55 # include <float.h> 56 #endif 57 58 #include <machine/fpu.h> 59 #include <stdio.h> 60 #include "gsl_ieee_utils.h" 61 #include "gsl_errno.h" 62 63 int 64 gsl_ieee_set_mode (int precision, int rounding, int exception_mask) 65 { 66 unsigned long int mode = 0 ; 67 unsigned int rnd = 0 ; 68 69 /* I'm actually not completely sure that the alpha only supports default 70 * precisions rounding, but I couldn't find any information regarding this, so 71 * it seems safe to assume this for now until it's proven otherwise. 72 */ 73 74 switch (precision) 75 { 76 case GSL_IEEE_SINGLE_PRECISION: 77 GSL_ERROR ("Tru64 Unix on the alpha only supports default precision rounding", 78 GSL_EUNSUP) ; 79 break ; 80 case GSL_IEEE_DOUBLE_PRECISION: 81 GSL_ERROR ("Tru64 Unix on the alpha only supports default precision rounding", 82 GSL_EUNSUP) ; 83 break ; 84 case GSL_IEEE_EXTENDED_PRECISION: 85 GSL_ERROR ("Tru64 Unix on the alpha only supports default precision rounding", 86 GSL_EUNSUP) ; 87 break ; 88 } 89 90 91 switch (rounding) 92 { 93 case GSL_IEEE_ROUND_TO_NEAREST: 94 rnd = FP_RND_RN ; 95 write_rnd (rnd) ; 96 break ; 97 case GSL_IEEE_ROUND_DOWN: 98 rnd = FP_RND_RM ; 99 write_rnd (rnd) ; 100 break ; 101 case GSL_IEEE_ROUND_UP: 102 rnd = FP_RND_RP ; 103 write_rnd (rnd) ; 104 break ; 105 case GSL_IEEE_ROUND_TO_ZERO: 106 rnd = FP_RND_RZ ; 107 write_rnd (rnd) ; 108 break ; 109 default: 110 rnd = FP_RND_RN ; 111 write_rnd (rnd) ; 112 } 113 114 /* Turn on all the exceptions apart from 'inexact' */ 115 116 /* from the ieee(3) man page: 117 * IEEE_TRAP_ENABLE_INV -> Invalid operation 118 * IEEE_TRAP_ENABLE_DZE -> Divide by 0 119 * IEEE_TRAP_ENABLE_OVF -> Overflow 120 * IEEE_TRAP_ENABLE_UNF -> Underflow 121 * IEEE_TRAP_ENABLE_INE -> Inexact (requires special option to C compiler) 122 * IEEE_TRAP_ENABLE_DNO -> denormal operand 123 * Note: IEEE_TRAP_ENABLE_DNO is not supported on OSF 3.x or Digital Unix 124 * 4.0 - 4.0d(?). 125 * IEEE_TRAP_ENABLE_MASK -> mask of all the trap enables 126 * IEEE_MAP_DMZ -> map denormal inputs to zero 127 * IEEE_MAP_UMZ -> map underflow results to zero 128 */ 129 130 mode = IEEE_TRAP_ENABLE_INV | IEEE_TRAP_ENABLE_DZE | IEEE_TRAP_ENABLE_OVF 131 | IEEE_TRAP_ENABLE_UNF ; 132 133 if (exception_mask & GSL_IEEE_MASK_INVALID) 134 mode &= ~ IEEE_TRAP_ENABLE_INV ; 135 136 if (exception_mask & GSL_IEEE_MASK_DENORMALIZED) 137 { 138 #ifdef IEEE_TRAP_ENABLE_DNO 139 mode &= ~ IEEE_TRAP_ENABLE_DNO ; 140 #else 141 GSL_ERROR ("Sorry, this version of Digital Unix does not support denormalized operands", GSL_EUNSUP) ; 142 #endif 143 } 144 145 if (exception_mask & GSL_IEEE_MASK_DIVISION_BY_ZERO) 146 mode &= ~ IEEE_TRAP_ENABLE_DZE ; 147 148 if (exception_mask & GSL_IEEE_MASK_OVERFLOW) 149 mode &= ~ IEEE_TRAP_ENABLE_OVF ; 150 151 if (exception_mask & GSL_IEEE_MASK_UNDERFLOW) 152 mode &= ~ IEEE_TRAP_ENABLE_UNF ; 153 154 if (exception_mask & GSL_IEEE_TRAP_INEXACT) 155 { 156 /* To implement this would require a special flag to the C 157 compiler which can cause degraded performance */ 158 159 GSL_ERROR ("Sorry, GSL does not implement trap-inexact for Tru64 Unix on the alpha - see fp-tru64.c for details", GSL_EUNSUP) ; 160 161 /* In case you need to add it, the appropriate line would be 162 * 163 * mode |= IEEE_TRAP_ENABLE_INE ; 164 * 165 */ 166 167 } 168 else 169 { 170 mode &= ~ IEEE_TRAP_ENABLE_INE ; 171 } 172 173 ieee_set_fp_control (mode) ; 174 175 return GSL_SUCCESS ; 176 } 177