Thomas Gleixner | 660662f | 2019-05-24 12:04:10 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | /* |
| 3 | * Linux/PA-RISC Project (http://www.parisc-linux.org/) |
| 4 | * |
| 5 | * Floating-point emulation code |
| 6 | * Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 7 | */ |
| 8 | /* |
| 9 | * BEGIN_DESC |
| 10 | * |
| 11 | * File: |
| 12 | * @(#) pa/spmath/sfrem.c $Revision: 1.1 $ |
| 13 | * |
| 14 | * Purpose: |
| 15 | * Single Precision Floating-point Remainder |
| 16 | * |
| 17 | * External Interfaces: |
| 18 | * sgl_frem(srcptr1,srcptr2,dstptr,status) |
| 19 | * |
| 20 | * Internal Interfaces: |
| 21 | * |
| 22 | * Theory: |
| 23 | * <<please update with a overview of the operation of this file>> |
| 24 | * |
| 25 | * END_DESC |
| 26 | */ |
| 27 | |
| 28 | |
| 29 | |
| 30 | #include "float.h" |
| 31 | #include "sgl_float.h" |
| 32 | |
| 33 | /* |
| 34 | * Single Precision Floating-point Remainder |
| 35 | */ |
| 36 | |
| 37 | int |
| 38 | sgl_frem (sgl_floating_point * srcptr1, sgl_floating_point * srcptr2, |
| 39 | sgl_floating_point * dstptr, unsigned int *status) |
| 40 | { |
| 41 | register unsigned int opnd1, opnd2, result; |
| 42 | register int opnd1_exponent, opnd2_exponent, dest_exponent, stepcount; |
| 43 | register boolean roundup = FALSE; |
| 44 | |
| 45 | opnd1 = *srcptr1; |
| 46 | opnd2 = *srcptr2; |
| 47 | /* |
| 48 | * check first operand for NaN's or infinity |
| 49 | */ |
| 50 | if ((opnd1_exponent = Sgl_exponent(opnd1)) == SGL_INFINITY_EXPONENT) { |
| 51 | if (Sgl_iszero_mantissa(opnd1)) { |
| 52 | if (Sgl_isnotnan(opnd2)) { |
| 53 | /* invalid since first operand is infinity */ |
| 54 | if (Is_invalidtrap_enabled()) |
| 55 | return(INVALIDEXCEPTION); |
| 56 | Set_invalidflag(); |
| 57 | Sgl_makequietnan(result); |
| 58 | *dstptr = result; |
| 59 | return(NOEXCEPTION); |
| 60 | } |
| 61 | } |
| 62 | else { |
| 63 | /* |
| 64 | * is NaN; signaling or quiet? |
| 65 | */ |
| 66 | if (Sgl_isone_signaling(opnd1)) { |
| 67 | /* trap if INVALIDTRAP enabled */ |
| 68 | if (Is_invalidtrap_enabled()) |
| 69 | return(INVALIDEXCEPTION); |
| 70 | /* make NaN quiet */ |
| 71 | Set_invalidflag(); |
| 72 | Sgl_set_quiet(opnd1); |
| 73 | } |
| 74 | /* |
| 75 | * is second operand a signaling NaN? |
| 76 | */ |
| 77 | else if (Sgl_is_signalingnan(opnd2)) { |
| 78 | /* trap if INVALIDTRAP enabled */ |
| 79 | if (Is_invalidtrap_enabled()) |
| 80 | return(INVALIDEXCEPTION); |
| 81 | /* make NaN quiet */ |
| 82 | Set_invalidflag(); |
| 83 | Sgl_set_quiet(opnd2); |
| 84 | *dstptr = opnd2; |
| 85 | return(NOEXCEPTION); |
| 86 | } |
| 87 | /* |
| 88 | * return quiet NaN |
| 89 | */ |
| 90 | *dstptr = opnd1; |
| 91 | return(NOEXCEPTION); |
| 92 | } |
| 93 | } |
| 94 | /* |
| 95 | * check second operand for NaN's or infinity |
| 96 | */ |
| 97 | if ((opnd2_exponent = Sgl_exponent(opnd2)) == SGL_INFINITY_EXPONENT) { |
| 98 | if (Sgl_iszero_mantissa(opnd2)) { |
| 99 | /* |
| 100 | * return first operand |
| 101 | */ |
| 102 | *dstptr = opnd1; |
| 103 | return(NOEXCEPTION); |
| 104 | } |
| 105 | /* |
| 106 | * is NaN; signaling or quiet? |
| 107 | */ |
| 108 | if (Sgl_isone_signaling(opnd2)) { |
| 109 | /* trap if INVALIDTRAP enabled */ |
| 110 | if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); |
| 111 | /* make NaN quiet */ |
| 112 | Set_invalidflag(); |
| 113 | Sgl_set_quiet(opnd2); |
| 114 | } |
| 115 | /* |
| 116 | * return quiet NaN |
| 117 | */ |
| 118 | *dstptr = opnd2; |
| 119 | return(NOEXCEPTION); |
| 120 | } |
| 121 | /* |
| 122 | * check second operand for zero |
| 123 | */ |
| 124 | if (Sgl_iszero_exponentmantissa(opnd2)) { |
| 125 | /* invalid since second operand is zero */ |
| 126 | if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); |
| 127 | Set_invalidflag(); |
| 128 | Sgl_makequietnan(result); |
| 129 | *dstptr = result; |
| 130 | return(NOEXCEPTION); |
| 131 | } |
| 132 | |
| 133 | /* |
| 134 | * get sign of result |
| 135 | */ |
| 136 | result = opnd1; |
| 137 | |
| 138 | /* |
| 139 | * check for denormalized operands |
| 140 | */ |
| 141 | if (opnd1_exponent == 0) { |
| 142 | /* check for zero */ |
| 143 | if (Sgl_iszero_mantissa(opnd1)) { |
| 144 | *dstptr = opnd1; |
| 145 | return(NOEXCEPTION); |
| 146 | } |
| 147 | /* normalize, then continue */ |
| 148 | opnd1_exponent = 1; |
| 149 | Sgl_normalize(opnd1,opnd1_exponent); |
| 150 | } |
| 151 | else { |
| 152 | Sgl_clear_signexponent_set_hidden(opnd1); |
| 153 | } |
| 154 | if (opnd2_exponent == 0) { |
| 155 | /* normalize, then continue */ |
| 156 | opnd2_exponent = 1; |
| 157 | Sgl_normalize(opnd2,opnd2_exponent); |
| 158 | } |
| 159 | else { |
| 160 | Sgl_clear_signexponent_set_hidden(opnd2); |
| 161 | } |
| 162 | |
| 163 | /* find result exponent and divide step loop count */ |
| 164 | dest_exponent = opnd2_exponent - 1; |
| 165 | stepcount = opnd1_exponent - opnd2_exponent; |
| 166 | |
| 167 | /* |
| 168 | * check for opnd1/opnd2 < 1 |
| 169 | */ |
| 170 | if (stepcount < 0) { |
| 171 | /* |
| 172 | * check for opnd1/opnd2 > 1/2 |
| 173 | * |
| 174 | * In this case n will round to 1, so |
| 175 | * r = opnd1 - opnd2 |
| 176 | */ |
| 177 | if (stepcount == -1 && Sgl_isgreaterthan(opnd1,opnd2)) { |
| 178 | Sgl_all(result) = ~Sgl_all(result); /* set sign */ |
| 179 | /* align opnd2 with opnd1 */ |
| 180 | Sgl_leftshiftby1(opnd2); |
| 181 | Sgl_subtract(opnd2,opnd1,opnd2); |
| 182 | /* now normalize */ |
| 183 | while (Sgl_iszero_hidden(opnd2)) { |
| 184 | Sgl_leftshiftby1(opnd2); |
| 185 | dest_exponent--; |
| 186 | } |
| 187 | Sgl_set_exponentmantissa(result,opnd2); |
| 188 | goto testforunderflow; |
| 189 | } |
| 190 | /* |
| 191 | * opnd1/opnd2 <= 1/2 |
| 192 | * |
| 193 | * In this case n will round to zero, so |
| 194 | * r = opnd1 |
| 195 | */ |
| 196 | Sgl_set_exponentmantissa(result,opnd1); |
| 197 | dest_exponent = opnd1_exponent; |
| 198 | goto testforunderflow; |
| 199 | } |
| 200 | |
| 201 | /* |
| 202 | * Generate result |
| 203 | * |
| 204 | * Do iterative subtract until remainder is less than operand 2. |
| 205 | */ |
| 206 | while (stepcount-- > 0 && Sgl_all(opnd1)) { |
| 207 | if (Sgl_isnotlessthan(opnd1,opnd2)) |
| 208 | Sgl_subtract(opnd1,opnd2,opnd1); |
| 209 | Sgl_leftshiftby1(opnd1); |
| 210 | } |
| 211 | /* |
| 212 | * Do last subtract, then determine which way to round if remainder |
| 213 | * is exactly 1/2 of opnd2 |
| 214 | */ |
| 215 | if (Sgl_isnotlessthan(opnd1,opnd2)) { |
| 216 | Sgl_subtract(opnd1,opnd2,opnd1); |
| 217 | roundup = TRUE; |
| 218 | } |
| 219 | if (stepcount > 0 || Sgl_iszero(opnd1)) { |
| 220 | /* division is exact, remainder is zero */ |
| 221 | Sgl_setzero_exponentmantissa(result); |
| 222 | *dstptr = result; |
| 223 | return(NOEXCEPTION); |
| 224 | } |
| 225 | |
| 226 | /* |
| 227 | * Check for cases where opnd1/opnd2 < n |
| 228 | * |
| 229 | * In this case the result's sign will be opposite that of |
| 230 | * opnd1. The mantissa also needs some correction. |
| 231 | */ |
| 232 | Sgl_leftshiftby1(opnd1); |
| 233 | if (Sgl_isgreaterthan(opnd1,opnd2)) { |
| 234 | Sgl_invert_sign(result); |
| 235 | Sgl_subtract((opnd2<<1),opnd1,opnd1); |
| 236 | } |
| 237 | /* check for remainder being exactly 1/2 of opnd2 */ |
| 238 | else if (Sgl_isequal(opnd1,opnd2) && roundup) { |
| 239 | Sgl_invert_sign(result); |
| 240 | } |
| 241 | |
| 242 | /* normalize result's mantissa */ |
| 243 | while (Sgl_iszero_hidden(opnd1)) { |
| 244 | dest_exponent--; |
| 245 | Sgl_leftshiftby1(opnd1); |
| 246 | } |
| 247 | Sgl_set_exponentmantissa(result,opnd1); |
| 248 | |
| 249 | /* |
| 250 | * Test for underflow |
| 251 | */ |
| 252 | testforunderflow: |
| 253 | if (dest_exponent <= 0) { |
| 254 | /* trap if UNDERFLOWTRAP enabled */ |
| 255 | if (Is_underflowtrap_enabled()) { |
| 256 | /* |
| 257 | * Adjust bias of result |
| 258 | */ |
| 259 | Sgl_setwrapped_exponent(result,dest_exponent,unfl); |
| 260 | *dstptr = result; |
| 261 | /* frem is always exact */ |
| 262 | return(UNDERFLOWEXCEPTION); |
| 263 | } |
| 264 | /* |
| 265 | * denormalize result or set to signed zero |
| 266 | */ |
| 267 | if (dest_exponent >= (1 - SGL_P)) { |
| 268 | Sgl_rightshift_exponentmantissa(result,1-dest_exponent); |
| 269 | } |
| 270 | else { |
| 271 | Sgl_setzero_exponentmantissa(result); |
| 272 | } |
| 273 | } |
| 274 | else Sgl_set_exponent(result,dest_exponent); |
| 275 | *dstptr = result; |
| 276 | return(NOEXCEPTION); |
| 277 | } |