| 1 | /* Decimal floating point support for GDB. |
| 2 | |
| 3 | Copyright 2007-2012 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of GDB. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | #include "defs.h" |
| 21 | #include "expression.h" |
| 22 | #include "gdbtypes.h" |
| 23 | #include "value.h" |
| 24 | #include "dfp.h" |
| 25 | |
| 26 | /* The order of the following headers is important for making sure |
| 27 | decNumber structure is large enough to hold decimal128 digits. */ |
| 28 | |
| 29 | #include "dpd/decimal128.h" |
| 30 | #include "dpd/decimal64.h" |
| 31 | #include "dpd/decimal32.h" |
| 32 | |
| 33 | /* In GDB, we are using an array of gdb_byte to represent decimal values. |
| 34 | They are stored in host byte order. This routine does the conversion if |
| 35 | the target byte order is different. */ |
| 36 | static void |
| 37 | match_endianness (const gdb_byte *from, int len, enum bfd_endian byte_order, |
| 38 | gdb_byte *to) |
| 39 | { |
| 40 | int i; |
| 41 | |
| 42 | #if WORDS_BIGENDIAN |
| 43 | #define OPPOSITE_BYTE_ORDER BFD_ENDIAN_LITTLE |
| 44 | #else |
| 45 | #define OPPOSITE_BYTE_ORDER BFD_ENDIAN_BIG |
| 46 | #endif |
| 47 | |
| 48 | if (byte_order == OPPOSITE_BYTE_ORDER) |
| 49 | for (i = 0; i < len; i++) |
| 50 | to[i] = from[len - i - 1]; |
| 51 | else |
| 52 | for (i = 0; i < len; i++) |
| 53 | to[i] = from[i]; |
| 54 | |
| 55 | return; |
| 56 | } |
| 57 | |
| 58 | /* Helper function to get the appropriate libdecnumber context for each size |
| 59 | of decimal float. */ |
| 60 | static void |
| 61 | set_decnumber_context (decContext *ctx, int len) |
| 62 | { |
| 63 | switch (len) |
| 64 | { |
| 65 | case 4: |
| 66 | decContextDefault (ctx, DEC_INIT_DECIMAL32); |
| 67 | break; |
| 68 | case 8: |
| 69 | decContextDefault (ctx, DEC_INIT_DECIMAL64); |
| 70 | break; |
| 71 | case 16: |
| 72 | decContextDefault (ctx, DEC_INIT_DECIMAL128); |
| 73 | break; |
| 74 | } |
| 75 | |
| 76 | ctx->traps = 0; |
| 77 | } |
| 78 | |
| 79 | /* Check for errors signaled in the decimal context structure. */ |
| 80 | static void |
| 81 | decimal_check_errors (decContext *ctx) |
| 82 | { |
| 83 | /* An error here could be a division by zero, an overflow, an underflow or |
| 84 | an invalid operation (from the DEC_Errors constant in decContext.h). |
| 85 | Since GDB doesn't complain about division by zero, overflow or underflow |
| 86 | errors for binary floating, we won't complain about them for decimal |
| 87 | floating either. */ |
| 88 | if (ctx->status & DEC_IEEE_854_Invalid_operation) |
| 89 | { |
| 90 | /* Leave only the error bits in the status flags. */ |
| 91 | ctx->status &= DEC_IEEE_854_Invalid_operation; |
| 92 | error (_("Cannot perform operation: %s"), |
| 93 | decContextStatusToString (ctx)); |
| 94 | } |
| 95 | } |
| 96 | |
| 97 | /* Helper function to convert from libdecnumber's appropriate representation |
| 98 | for computation to each size of decimal float. */ |
| 99 | static void |
| 100 | decimal_from_number (const decNumber *from, gdb_byte *to, int len) |
| 101 | { |
| 102 | decContext set; |
| 103 | |
| 104 | set_decnumber_context (&set, len); |
| 105 | |
| 106 | switch (len) |
| 107 | { |
| 108 | case 4: |
| 109 | decimal32FromNumber ((decimal32 *) to, from, &set); |
| 110 | break; |
| 111 | case 8: |
| 112 | decimal64FromNumber ((decimal64 *) to, from, &set); |
| 113 | break; |
| 114 | case 16: |
| 115 | decimal128FromNumber ((decimal128 *) to, from, &set); |
| 116 | break; |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | /* Helper function to convert each size of decimal float to libdecnumber's |
| 121 | appropriate representation for computation. */ |
| 122 | static void |
| 123 | decimal_to_number (const gdb_byte *from, int len, decNumber *to) |
| 124 | { |
| 125 | switch (len) |
| 126 | { |
| 127 | case 4: |
| 128 | decimal32ToNumber ((decimal32 *) from, to); |
| 129 | break; |
| 130 | case 8: |
| 131 | decimal64ToNumber ((decimal64 *) from, to); |
| 132 | break; |
| 133 | case 16: |
| 134 | decimal128ToNumber ((decimal128 *) from, to); |
| 135 | break; |
| 136 | default: |
| 137 | error (_("Unknown decimal floating point type.")); |
| 138 | break; |
| 139 | } |
| 140 | } |
| 141 | |
| 142 | /* Convert decimal type to its string representation. LEN is the length |
| 143 | of the decimal type, 4 bytes for decimal32, 8 bytes for decimal64 and |
| 144 | 16 bytes for decimal128. */ |
| 145 | void |
| 146 | decimal_to_string (const gdb_byte *decbytes, int len, |
| 147 | enum bfd_endian byte_order, char *s) |
| 148 | { |
| 149 | gdb_byte dec[16]; |
| 150 | |
| 151 | match_endianness (decbytes, len, byte_order, dec); |
| 152 | |
| 153 | switch (len) |
| 154 | { |
| 155 | case 4: |
| 156 | decimal32ToString ((decimal32 *) dec, s); |
| 157 | break; |
| 158 | case 8: |
| 159 | decimal64ToString ((decimal64 *) dec, s); |
| 160 | break; |
| 161 | case 16: |
| 162 | decimal128ToString ((decimal128 *) dec, s); |
| 163 | break; |
| 164 | default: |
| 165 | error (_("Unknown decimal floating point type.")); |
| 166 | break; |
| 167 | } |
| 168 | } |
| 169 | |
| 170 | /* Convert the string form of a decimal value to its decimal representation. |
| 171 | LEN is the length of the decimal type, 4 bytes for decimal32, 8 bytes for |
| 172 | decimal64 and 16 bytes for decimal128. */ |
| 173 | int |
| 174 | decimal_from_string (gdb_byte *decbytes, int len, enum bfd_endian byte_order, |
| 175 | const char *string) |
| 176 | { |
| 177 | decContext set; |
| 178 | gdb_byte dec[16]; |
| 179 | |
| 180 | set_decnumber_context (&set, len); |
| 181 | |
| 182 | switch (len) |
| 183 | { |
| 184 | case 4: |
| 185 | decimal32FromString ((decimal32 *) dec, string, &set); |
| 186 | break; |
| 187 | case 8: |
| 188 | decimal64FromString ((decimal64 *) dec, string, &set); |
| 189 | break; |
| 190 | case 16: |
| 191 | decimal128FromString ((decimal128 *) dec, string, &set); |
| 192 | break; |
| 193 | default: |
| 194 | error (_("Unknown decimal floating point type.")); |
| 195 | break; |
| 196 | } |
| 197 | |
| 198 | match_endianness (dec, len, byte_order, decbytes); |
| 199 | |
| 200 | /* Check for errors in the DFP operation. */ |
| 201 | decimal_check_errors (&set); |
| 202 | |
| 203 | return 1; |
| 204 | } |
| 205 | |
| 206 | /* Converts a value of an integral type to a decimal float of |
| 207 | specified LEN bytes. */ |
| 208 | void |
| 209 | decimal_from_integral (struct value *from, |
| 210 | gdb_byte *to, int len, enum bfd_endian byte_order) |
| 211 | { |
| 212 | LONGEST l; |
| 213 | gdb_byte dec[16]; |
| 214 | decNumber number; |
| 215 | struct type *type; |
| 216 | |
| 217 | type = check_typedef (value_type (from)); |
| 218 | |
| 219 | if (TYPE_LENGTH (type) > 4) |
| 220 | /* libdecnumber can convert only 32-bit integers. */ |
| 221 | error (_("Conversion of large integer to a " |
| 222 | "decimal floating type is not supported.")); |
| 223 | |
| 224 | l = value_as_long (from); |
| 225 | |
| 226 | if (TYPE_UNSIGNED (type)) |
| 227 | decNumberFromUInt32 (&number, (unsigned int) l); |
| 228 | else |
| 229 | decNumberFromInt32 (&number, (int) l); |
| 230 | |
| 231 | decimal_from_number (&number, dec, len); |
| 232 | match_endianness (dec, len, byte_order, to); |
| 233 | } |
| 234 | |
| 235 | /* Converts a value of a float type to a decimal float of |
| 236 | specified LEN bytes. |
| 237 | |
| 238 | This is an ugly way to do the conversion, but libdecnumber does |
| 239 | not offer a direct way to do it. */ |
| 240 | void |
| 241 | decimal_from_floating (struct value *from, |
| 242 | gdb_byte *to, int len, enum bfd_endian byte_order) |
| 243 | { |
| 244 | char *buffer; |
| 245 | |
| 246 | buffer = xstrprintf ("%.30" DOUBLEST_PRINT_FORMAT, value_as_double (from)); |
| 247 | |
| 248 | decimal_from_string (to, len, byte_order, buffer); |
| 249 | |
| 250 | xfree (buffer); |
| 251 | } |
| 252 | |
| 253 | /* Converts a decimal float of LEN bytes to a double value. */ |
| 254 | DOUBLEST |
| 255 | decimal_to_doublest (const gdb_byte *from, int len, enum bfd_endian byte_order) |
| 256 | { |
| 257 | char buffer[MAX_DECIMAL_STRING]; |
| 258 | |
| 259 | /* This is an ugly way to do the conversion, but libdecnumber does |
| 260 | not offer a direct way to do it. */ |
| 261 | decimal_to_string (from, len, byte_order, buffer); |
| 262 | return strtod (buffer, NULL); |
| 263 | } |
| 264 | |
| 265 | /* Perform operation OP with operands X and Y with sizes LEN_X and LEN_Y |
| 266 | and byte orders BYTE_ORDER_X and BYTE_ORDER_Y, and store value in |
| 267 | RESULT with size LEN_RESULT and byte order BYTE_ORDER_RESULT. */ |
| 268 | void |
| 269 | decimal_binop (enum exp_opcode op, |
| 270 | const gdb_byte *x, int len_x, enum bfd_endian byte_order_x, |
| 271 | const gdb_byte *y, int len_y, enum bfd_endian byte_order_y, |
| 272 | gdb_byte *result, int len_result, |
| 273 | enum bfd_endian byte_order_result) |
| 274 | { |
| 275 | decContext set; |
| 276 | decNumber number1, number2, number3; |
| 277 | gdb_byte dec1[16], dec2[16], dec3[16]; |
| 278 | |
| 279 | match_endianness (x, len_x, byte_order_x, dec1); |
| 280 | match_endianness (y, len_y, byte_order_y, dec2); |
| 281 | |
| 282 | decimal_to_number (dec1, len_x, &number1); |
| 283 | decimal_to_number (dec2, len_y, &number2); |
| 284 | |
| 285 | set_decnumber_context (&set, len_result); |
| 286 | |
| 287 | switch (op) |
| 288 | { |
| 289 | case BINOP_ADD: |
| 290 | decNumberAdd (&number3, &number1, &number2, &set); |
| 291 | break; |
| 292 | case BINOP_SUB: |
| 293 | decNumberSubtract (&number3, &number1, &number2, &set); |
| 294 | break; |
| 295 | case BINOP_MUL: |
| 296 | decNumberMultiply (&number3, &number1, &number2, &set); |
| 297 | break; |
| 298 | case BINOP_DIV: |
| 299 | decNumberDivide (&number3, &number1, &number2, &set); |
| 300 | break; |
| 301 | case BINOP_EXP: |
| 302 | decNumberPower (&number3, &number1, &number2, &set); |
| 303 | break; |
| 304 | default: |
| 305 | internal_error (__FILE__, __LINE__, |
| 306 | _("Unknown decimal floating point operation.")); |
| 307 | break; |
| 308 | } |
| 309 | |
| 310 | /* Check for errors in the DFP operation. */ |
| 311 | decimal_check_errors (&set); |
| 312 | |
| 313 | decimal_from_number (&number3, dec3, len_result); |
| 314 | |
| 315 | match_endianness (dec3, len_result, byte_order_result, result); |
| 316 | } |
| 317 | |
| 318 | /* Returns true if X (which is LEN bytes wide) is the number zero. */ |
| 319 | int |
| 320 | decimal_is_zero (const gdb_byte *x, int len, enum bfd_endian byte_order) |
| 321 | { |
| 322 | decNumber number; |
| 323 | gdb_byte dec[16]; |
| 324 | |
| 325 | match_endianness (x, len, byte_order, dec); |
| 326 | decimal_to_number (dec, len, &number); |
| 327 | |
| 328 | return decNumberIsZero (&number); |
| 329 | } |
| 330 | |
| 331 | /* Compares two numbers numerically. If X is less than Y then the return value |
| 332 | will be -1. If they are equal, then the return value will be 0. If X is |
| 333 | greater than the Y then the return value will be 1. */ |
| 334 | int |
| 335 | decimal_compare (const gdb_byte *x, int len_x, enum bfd_endian byte_order_x, |
| 336 | const gdb_byte *y, int len_y, enum bfd_endian byte_order_y) |
| 337 | { |
| 338 | decNumber number1, number2, result; |
| 339 | decContext set; |
| 340 | gdb_byte dec1[16], dec2[16]; |
| 341 | int len_result; |
| 342 | |
| 343 | match_endianness (x, len_x, byte_order_x, dec1); |
| 344 | match_endianness (y, len_y, byte_order_y, dec2); |
| 345 | |
| 346 | decimal_to_number (dec1, len_x, &number1); |
| 347 | decimal_to_number (dec2, len_y, &number2); |
| 348 | |
| 349 | /* Perform the comparison in the larger of the two sizes. */ |
| 350 | len_result = len_x > len_y ? len_x : len_y; |
| 351 | set_decnumber_context (&set, len_result); |
| 352 | |
| 353 | decNumberCompare (&result, &number1, &number2, &set); |
| 354 | |
| 355 | /* Check for errors in the DFP operation. */ |
| 356 | decimal_check_errors (&set); |
| 357 | |
| 358 | if (decNumberIsNaN (&result)) |
| 359 | error (_("Comparison with an invalid number (NaN).")); |
| 360 | else if (decNumberIsZero (&result)) |
| 361 | return 0; |
| 362 | else if (decNumberIsNegative (&result)) |
| 363 | return -1; |
| 364 | else |
| 365 | return 1; |
| 366 | } |
| 367 | |
| 368 | /* Convert a decimal value from a decimal type with LEN_FROM bytes to a |
| 369 | decimal type with LEN_TO bytes. */ |
| 370 | void |
| 371 | decimal_convert (const gdb_byte *from, int len_from, |
| 372 | enum bfd_endian byte_order_from, gdb_byte *to, int len_to, |
| 373 | enum bfd_endian byte_order_to) |
| 374 | { |
| 375 | decNumber number; |
| 376 | gdb_byte dec[16]; |
| 377 | |
| 378 | match_endianness (from, len_from, byte_order_from, dec); |
| 379 | |
| 380 | decimal_to_number (dec, len_from, &number); |
| 381 | decimal_from_number (&number, dec, len_to); |
| 382 | |
| 383 | match_endianness (dec, len_to, byte_order_to, to); |
| 384 | } |