1 /* $NetBSD: sfrem.c,v 1.4 2007/02/22 05:46:30 thorpej Exp $ */ 2 3 /* $OpenBSD: sfrem.c,v 1.4 2001/03/29 03:58:19 mickey Exp $ */ 4 5 /* 6 * Copyright 1996 1995 by Open Software Foundation, Inc. 7 * All Rights Reserved 8 * 9 * Permission to use, copy, modify, and distribute this software and 10 * its documentation for any purpose and without fee is hereby granted, 11 * provided that the above copyright notice appears in all copies and 12 * that both the copyright notice and this permission notice appear in 13 * supporting documentation. 14 * 15 * OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE 16 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 17 * FOR A PARTICULAR PURPOSE. 18 * 19 * IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR 20 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 21 * LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT, 22 * NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION 23 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 24 * 25 */ 26 /* 27 * pmk1.1 28 */ 29 /* 30 * (c) Copyright 1986 HEWLETT-PACKARD COMPANY 31 * 32 * To anyone who acknowledges that this file is provided "AS IS" 33 * without any express or implied warranty: 34 * permission to use, copy, modify, and distribute this file 35 * for any purpose is hereby granted without fee, provided that 36 * the above copyright notice and this notice appears in all 37 * copies, and that the name of Hewlett-Packard Company not be 38 * used in advertising or publicity pertaining to distribution 39 * of the software without specific, written prior permission. 40 * Hewlett-Packard Company makes no representations about the 41 * suitability of this software for any purpose. 42 */ 43 44 #include <sys/cdefs.h> 45 __KERNEL_RCSID(0, "$NetBSD: sfrem.c,v 1.4 2007/02/22 05:46:30 thorpej Exp $"); 46 47 #include "../spmath/float.h" 48 #include "../spmath/sgl_float.h" 49 50 /* 51 * Single Precision Floating-point Remainder 52 */ 53 int 54 sgl_frem(srcptr1,srcptr2,dstptr,status) 55 56 sgl_floating_point *srcptr1, *srcptr2, *dstptr; 57 unsigned int *status; 58 { 59 register unsigned int opnd1, opnd2, result; 60 register int opnd1_exponent, opnd2_exponent, dest_exponent, stepcount; 61 register int roundup = false; 62 63 opnd1 = *srcptr1; 64 opnd2 = *srcptr2; 65 /* 66 * check first operand for NaN's or infinity 67 */ 68 if ((opnd1_exponent = Sgl_exponent(opnd1)) == SGL_INFINITY_EXPONENT) { 69 if (Sgl_iszero_mantissa(opnd1)) { 70 if (Sgl_isnotnan(opnd2)) { 71 /* invalid since first operand is infinity */ 72 if (Is_invalidtrap_enabled()) 73 return(INVALIDEXCEPTION); 74 Set_invalidflag(); 75 Sgl_makequietnan(result); 76 *dstptr = result; 77 return(NOEXCEPTION); 78 } 79 } 80 else { 81 /* 82 * is NaN; signaling or quiet? 83 */ 84 if (Sgl_isone_signaling(opnd1)) { 85 /* trap if INVALIDTRAP enabled */ 86 if (Is_invalidtrap_enabled()) 87 return(INVALIDEXCEPTION); 88 /* make NaN quiet */ 89 Set_invalidflag(); 90 Sgl_set_quiet(opnd1); 91 } 92 /* 93 * is second operand a signaling NaN? 94 */ 95 else if (Sgl_is_signalingnan(opnd2)) { 96 /* trap if INVALIDTRAP enabled */ 97 if (Is_invalidtrap_enabled()) 98 return(INVALIDEXCEPTION); 99 /* make NaN quiet */ 100 Set_invalidflag(); 101 Sgl_set_quiet(opnd2); 102 *dstptr = opnd2; 103 return(NOEXCEPTION); 104 } 105 /* 106 * return quiet NaN 107 */ 108 *dstptr = opnd1; 109 return(NOEXCEPTION); 110 } 111 } 112 /* 113 * check second operand for NaN's or infinity 114 */ 115 if ((opnd2_exponent = Sgl_exponent(opnd2)) == SGL_INFINITY_EXPONENT) { 116 if (Sgl_iszero_mantissa(opnd2)) { 117 /* 118 * return first operand 119 */ 120 *dstptr = opnd1; 121 return(NOEXCEPTION); 122 } 123 /* 124 * is NaN; signaling or quiet? 125 */ 126 if (Sgl_isone_signaling(opnd2)) { 127 /* trap if INVALIDTRAP enabled */ 128 if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); 129 /* make NaN quiet */ 130 Set_invalidflag(); 131 Sgl_set_quiet(opnd2); 132 } 133 /* 134 * return quiet NaN 135 */ 136 *dstptr = opnd2; 137 return(NOEXCEPTION); 138 } 139 /* 140 * check second operand for zero 141 */ 142 if (Sgl_iszero_exponentmantissa(opnd2)) { 143 /* invalid since second operand is zero */ 144 if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); 145 Set_invalidflag(); 146 Sgl_makequietnan(result); 147 *dstptr = result; 148 return(NOEXCEPTION); 149 } 150 151 /* 152 * get sign of result 153 */ 154 result = opnd1; 155 156 /* 157 * check for denormalized operands 158 */ 159 if (opnd1_exponent == 0) { 160 /* check for zero */ 161 if (Sgl_iszero_mantissa(opnd1)) { 162 *dstptr = opnd1; 163 return(NOEXCEPTION); 164 } 165 /* normalize, then continue */ 166 opnd1_exponent = 1; 167 Sgl_normalize(opnd1,opnd1_exponent); 168 } 169 else { 170 Sgl_clear_signexponent_set_hidden(opnd1); 171 } 172 if (opnd2_exponent == 0) { 173 /* normalize, then continue */ 174 opnd2_exponent = 1; 175 Sgl_normalize(opnd2,opnd2_exponent); 176 } 177 else { 178 Sgl_clear_signexponent_set_hidden(opnd2); 179 } 180 181 /* find result exponent and divide step loop count */ 182 dest_exponent = opnd2_exponent - 1; 183 stepcount = opnd1_exponent - opnd2_exponent; 184 185 /* 186 * check for opnd1/opnd2 < 1 187 */ 188 if (stepcount < 0) { 189 /* 190 * check for opnd1/opnd2 > 1/2 191 * 192 * In this case n will round to 1, so 193 * r = opnd1 - opnd2 194 */ 195 if (stepcount == -1 && Sgl_isgreaterthan(opnd1,opnd2)) { 196 Sgl_all(result) = ~Sgl_all(result); /* set sign */ 197 /* align opnd2 with opnd1 */ 198 Sgl_leftshiftby1(opnd2); 199 Sgl_subtract(opnd2,opnd1,opnd2); 200 /* now normalize */ 201 while (Sgl_iszero_hidden(opnd2)) { 202 Sgl_leftshiftby1(opnd2); 203 dest_exponent--; 204 } 205 Sgl_set_exponentmantissa(result,opnd2); 206 goto testforunderflow; 207 } 208 /* 209 * opnd1/opnd2 <= 1/2 210 * 211 * In this case n will round to zero, so 212 * r = opnd1 213 */ 214 Sgl_set_exponentmantissa(result,opnd1); 215 dest_exponent = opnd1_exponent; 216 goto testforunderflow; 217 } 218 219 /* 220 * Generate result 221 * 222 * Do iterative subtract until remainder is less than operand 2. 223 */ 224 while (stepcount-- > 0 && Sgl_all(opnd1)) { 225 if (Sgl_isnotlessthan(opnd1,opnd2)) 226 Sgl_subtract(opnd1,opnd2,opnd1); 227 Sgl_leftshiftby1(opnd1); 228 } 229 /* 230 * Do last subtract, then determine which way to round if remainder 231 * is exactly 1/2 of opnd2 232 */ 233 if (Sgl_isnotlessthan(opnd1,opnd2)) { 234 Sgl_subtract(opnd1,opnd2,opnd1); 235 roundup = true; 236 } 237 if (stepcount > 0 || Sgl_iszero(opnd1)) { 238 /* division is exact, remainder is zero */ 239 Sgl_setzero_exponentmantissa(result); 240 *dstptr = result; 241 return(NOEXCEPTION); 242 } 243 244 /* 245 * Check for cases where opnd1/opnd2 < n 246 * 247 * In this case the result's sign will be opposite that of 248 * opnd1. The mantissa also needs some correction. 249 */ 250 Sgl_leftshiftby1(opnd1); 251 if (Sgl_isgreaterthan(opnd1,opnd2)) { 252 Sgl_invert_sign(result); 253 Sgl_subtract((opnd2<<1),opnd1,opnd1); 254 } 255 /* check for remainder being exactly 1/2 of opnd2 */ 256 else if (Sgl_isequal(opnd1,opnd2) && roundup) { 257 Sgl_invert_sign(result); 258 } 259 260 /* normalize result's mantissa */ 261 while (Sgl_iszero_hidden(opnd1)) { 262 dest_exponent--; 263 Sgl_leftshiftby1(opnd1); 264 } 265 Sgl_set_exponentmantissa(result,opnd1); 266 267 /* 268 * Test for underflow 269 */ 270 testforunderflow: 271 if (dest_exponent <= 0) { 272 /* trap if UNDERFLOWTRAP enabled */ 273 if (Is_underflowtrap_enabled()) { 274 /* 275 * Adjust bias of result 276 */ 277 Sgl_setwrapped_exponent(result,dest_exponent,unfl); 278 *dstptr = result; 279 /* frem is always exact */ 280 return(UNDERFLOWEXCEPTION); 281 } 282 /* 283 * denormalize result or set to signed zero 284 */ 285 if (dest_exponent >= (1 - SGL_P)) { 286 Sgl_rightshift_exponentmantissa(result,1-dest_exponent); 287 } else { 288 Sgl_setzero_exponentmantissa(result); 289 } 290 } 291 else Sgl_set_exponent(result,dest_exponent); 292 *dstptr = result; 293 return(NOEXCEPTION); 294 } 295