1 /* 2 * x86 FPREM test - executes the FPREM and FPREM1 instructions with corner case 3 * operands and prints the operands, result and FPU status word. 4 * 5 * Run this on real hardware, then under QEMU, and diff the outputs, to compare 6 * QEMU's implementation to your hardware. The 'run-test-i386-fprem' make 7 * target does this. 8 * 9 * Copyright (c) 2003 Fabrice Bellard 10 * Copyright (c) 2012 Catalin Patulea 11 * 12 * This program is free software; you can redistribute it and/or modify 13 * it under the terms of the GNU General Public License as published by 14 * the Free Software Foundation; either version 2 of the License, or 15 * (at your option) any later version. 16 * 17 * This program is distributed in the hope that it will be useful, 18 * but WITHOUT ANY WARRANTY; without even the implied warranty of 19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 20 * GNU General Public License for more details. 21 * 22 * You should have received a copy of the GNU General Public License 23 * along with this program; if not, see <http://www.gnu.org/licenses/>. 24 */ 25 26 #include <stdio.h> 27 #include <stdint.h> 28 29 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) 30 31 /* 32 * Inspired by <ieee754.h>'s union ieee854_long_double, but with single 33 * long long mantissa fields and assuming little-endianness for simplicity. 34 */ 35 union float80u { 36 long double d; 37 38 /* This is the IEEE 854 double-extended-precision format. */ 39 struct { 40 unsigned long long mantissa:63; 41 unsigned int one:1; 42 unsigned int exponent:15; 43 unsigned int negative:1; 44 unsigned int empty:16; 45 } __attribute__((packed)) ieee; 46 47 /* This is for NaNs in the IEEE 854 double-extended-precision format. */ 48 struct { 49 unsigned long long mantissa:62; 50 unsigned int quiet_nan:1; 51 unsigned int one:1; 52 unsigned int exponent:15; 53 unsigned int negative:1; 54 unsigned int empty:16; 55 } __attribute__((packed)) ieee_nan; 56 }; 57 58 #define IEEE854_LONG_DOUBLE_BIAS 0x3fff 59 60 static const union float80u q_nan = { 61 .ieee_nan.negative = 0, /* X */ 62 .ieee_nan.exponent = 0x7fff, 63 .ieee_nan.one = 1, 64 .ieee_nan.quiet_nan = 1, 65 .ieee_nan.mantissa = 0, 66 }; 67 68 static const union float80u s_nan = { 69 .ieee_nan.negative = 0, /* X */ 70 .ieee_nan.exponent = 0x7fff, 71 .ieee_nan.one = 1, 72 .ieee_nan.quiet_nan = 0, 73 .ieee_nan.mantissa = 1, /* nonzero */ 74 }; 75 76 static const union float80u pos_inf = { 77 .ieee.negative = 0, 78 .ieee.exponent = 0x7fff, 79 .ieee.one = 1, 80 .ieee.mantissa = 0, 81 }; 82 83 static const union float80u pseudo_pos_inf = { /* "unsupported" */ 84 .ieee.negative = 0, 85 .ieee.exponent = 0x7fff, 86 .ieee.one = 0, 87 .ieee.mantissa = 0, 88 }; 89 90 static const union float80u pos_denorm = { 91 .ieee.negative = 0, 92 .ieee.exponent = 0, 93 .ieee.one = 0, 94 .ieee.mantissa = 1, 95 }; 96 97 static const union float80u smallest_positive_norm = { 98 .ieee.negative = 0, 99 .ieee.exponent = 1, 100 .ieee.one = 1, 101 .ieee.mantissa = 0, 102 }; 103 fninit()104 static void fninit() 105 { 106 asm volatile ("fninit\n"); 107 } 108 fprem(long double a,long double b,uint16_t * sw)109 static long double fprem(long double a, long double b, uint16_t *sw) 110 { 111 long double result; 112 asm volatile ("fprem\n" 113 "fnstsw %1\n" 114 : "=t" (result), "=m" (*sw) 115 : "0" (a), "u" (b) 116 : "st(1)"); 117 return result; 118 } 119 fprem1(long double a,long double b,uint16_t * sw)120 static long double fprem1(long double a, long double b, uint16_t *sw) 121 { 122 long double result; 123 asm volatile ("fprem1\n" 124 "fnstsw %1\n" 125 : "=t" (result), "=m" (*sw) 126 : "0" (a), "u" (b) 127 : "st(1)"); 128 return result; 129 } 130 131 #define FPUS_IE (1 << 0) 132 #define FPUS_DE (1 << 1) 133 #define FPUS_ZE (1 << 2) 134 #define FPUS_OE (1 << 3) 135 #define FPUS_UE (1 << 4) 136 #define FPUS_PE (1 << 5) 137 #define FPUS_SF (1 << 6) 138 #define FPUS_SE (1 << 7) 139 #define FPUS_C0 (1 << 8) 140 #define FPUS_C1 (1 << 9) 141 #define FPUS_C2 (1 << 10) 142 #define FPUS_TOP 0x3800 143 #define FPUS_C3 (1 << 14) 144 #define FPUS_B (1 << 15) 145 146 #define FPUS_EMASK 0x007f 147 148 #define FPUC_EM 0x3f 149 psw(uint16_t sw)150 static void psw(uint16_t sw) 151 { 152 printf("SW: C3 TopC2C1C0\n"); 153 printf("SW: %c %d %3d %d %d %d %c %c %c %c %c %c %c %c\n", 154 sw & FPUS_B ? 'B' : 'b', 155 !!(sw & FPUS_C3), 156 (sw & FPUS_TOP) >> 11, 157 !!(sw & FPUS_C2), 158 !!(sw & FPUS_C1), 159 !!(sw & FPUS_C0), 160 (sw & FPUS_SE) ? 'S' : 's', 161 (sw & FPUS_SF) ? 'F' : 'f', 162 (sw & FPUS_PE) ? 'P' : 'p', 163 (sw & FPUS_UE) ? 'U' : 'u', 164 (sw & FPUS_OE) ? 'O' : 'o', 165 (sw & FPUS_ZE) ? 'Z' : 'z', 166 (sw & FPUS_DE) ? 'D' : 'd', 167 (sw & FPUS_IE) ? 'I' : 'i'); 168 } 169 do_fprem(long double a,long double b)170 static void do_fprem(long double a, long double b) 171 { 172 const union float80u au = {.d = a}; 173 const union float80u bu = {.d = b}; 174 union float80u ru; 175 uint16_t sw; 176 177 printf("A: S=%d Exp=%04x Int=%d (QNaN=%d) Sig=%016llx (%.06Le)\n", 178 au.ieee.negative, au.ieee.exponent, au.ieee.one, 179 au.ieee_nan.quiet_nan, (unsigned long long)au.ieee.mantissa, 180 a); 181 printf("B: S=%d Exp=%04x Int=%d (QNaN=%d) Sig=%016llx (%.06Le)\n", 182 bu.ieee.negative, bu.ieee.exponent, bu.ieee.one, 183 bu.ieee_nan.quiet_nan, (unsigned long long)bu.ieee.mantissa, 184 b); 185 fflush(stdout); 186 187 fninit(); 188 ru.d = fprem(a, b, &sw); 189 psw(sw); 190 191 printf("R : S=%d Exp=%04x Int=%d (QNaN=%d) Sig=%016llx (%.06Le)\n", 192 ru.ieee.negative, ru.ieee.exponent, ru.ieee.one, 193 ru.ieee_nan.quiet_nan, (unsigned long long)ru.ieee.mantissa, 194 ru.d); 195 196 fninit(); 197 ru.d = fprem1(a, b, &sw); 198 psw(sw); 199 200 printf("R1: S=%d Exp=%04x Int=%d (QNaN=%d) Sig=%016llx (%.06Le)\n", 201 ru.ieee.negative, ru.ieee.exponent, ru.ieee.one, 202 ru.ieee_nan.quiet_nan, (unsigned long long)ru.ieee.mantissa, 203 ru.d); 204 205 printf("\n"); 206 } 207 do_fprem_stack_underflow(void)208 static void do_fprem_stack_underflow(void) 209 { 210 const long double a = 1.0; 211 union float80u ru; 212 uint16_t sw; 213 214 fninit(); 215 asm volatile ("fprem\n" 216 "fnstsw %1\n" 217 : "=t" (ru.d), "=m" (sw) 218 : "0" (a) 219 : "st(1)"); 220 psw(sw); 221 222 printf("R: S=%d Exp=%04x Int=%d (QNaN=%d) Sig=%016llx (%.06Le)\n", 223 ru.ieee.negative, ru.ieee.exponent, ru.ieee.one, 224 ru.ieee_nan.quiet_nan, (unsigned long long)ru.ieee.mantissa, 225 ru.d); 226 printf("\n"); 227 } 228 test_fprem_cases(void)229 static void test_fprem_cases(void) 230 { 231 printf("= stack underflow =\n"); 232 do_fprem_stack_underflow(); 233 234 printf("= invalid operation =\n"); 235 do_fprem(q_nan.d, 1.0); 236 do_fprem(s_nan.d, 1.0); 237 do_fprem(1.0, 0.0); 238 do_fprem(pos_inf.d, 1.0); 239 do_fprem(pseudo_pos_inf.d, 1.0); 240 241 printf("= denormal =\n"); 242 do_fprem(pos_denorm.d, 1.0); 243 do_fprem(1.0, pos_denorm.d); 244 245 do_fprem(smallest_positive_norm.d, smallest_positive_norm.d); 246 247 /* printf("= underflow =\n"); */ 248 /* TODO: Is there a case where FPREM raises underflow? */ 249 } 250 test_fprem_pairs(void)251 static void test_fprem_pairs(void) 252 { 253 unsigned long long count; 254 255 unsigned int negative_index_a = 0; 256 unsigned int negative_index_b = 0; 257 static const unsigned int negative_values[] = { 258 0, 259 1, 260 }; 261 262 unsigned int exponent_index_a = 0; 263 unsigned int exponent_index_b = 0; 264 static const unsigned int exponent_values[] = { 265 0, 266 1, 267 2, 268 IEEE854_LONG_DOUBLE_BIAS - 1, 269 IEEE854_LONG_DOUBLE_BIAS, 270 IEEE854_LONG_DOUBLE_BIAS + 1, 271 0x7ffd, 272 0x7ffe, 273 0x7fff, 274 }; 275 276 unsigned int one_index_a = 0; 277 unsigned int one_index_b = 0; 278 static const unsigned int one_values[] = { 279 0, 280 1, 281 }; 282 283 unsigned int quiet_nan_index_a = 0; 284 unsigned int quiet_nan_index_b = 0; 285 static const unsigned int quiet_nan_values[] = { 286 0, 287 1, 288 }; 289 290 unsigned int mantissa_index_a = 0; 291 unsigned int mantissa_index_b = 0; 292 static const unsigned long long mantissa_values[] = { 293 0, 294 1, 295 2, 296 0x3ffffffffffffffdULL, 297 0x3ffffffffffffffeULL, 298 0x3fffffffffffffffULL, 299 }; 300 301 for (count = 0; ; ++count) { 302 #define INIT_FIELD(var, field) \ 303 .ieee_nan.field = field##_values[field##_index_##var] 304 const union float80u a = { 305 INIT_FIELD(a, negative), 306 INIT_FIELD(a, exponent), 307 INIT_FIELD(a, one), 308 INIT_FIELD(a, quiet_nan), 309 INIT_FIELD(a, mantissa), 310 }; 311 const union float80u b = { 312 INIT_FIELD(b, negative), 313 INIT_FIELD(b, exponent), 314 INIT_FIELD(b, one), 315 INIT_FIELD(b, quiet_nan), 316 INIT_FIELD(b, mantissa), 317 }; 318 #undef INIT_FIELD 319 320 do_fprem(a.d, b.d); 321 322 int carry = 1; 323 #define CARRY_INTO(var, field) do { \ 324 if (carry) { \ 325 if (++field##_index_##var == ARRAY_SIZE(field##_values)) { \ 326 field##_index_##var = 0; \ 327 } else { \ 328 carry = 0; \ 329 } \ 330 } \ 331 } while (0) 332 CARRY_INTO(b, mantissa); 333 CARRY_INTO(b, quiet_nan); 334 CARRY_INTO(b, one); 335 CARRY_INTO(b, exponent); 336 CARRY_INTO(b, negative); 337 CARRY_INTO(a, mantissa); 338 CARRY_INTO(a, quiet_nan); 339 CARRY_INTO(a, one); 340 CARRY_INTO(a, exponent); 341 CARRY_INTO(a, negative); 342 #undef CARRY_INTO 343 344 if (carry) { 345 break; 346 } 347 } 348 349 fprintf(stderr, "test-i386-fprem: tested %llu cases\n", count); 350 } 351 main(int argc,char ** argv)352 int main(int argc, char **argv) 353 { 354 test_fprem_cases(); 355 test_fprem_pairs(); 356 return 0; 357 } 358