Changes in uspace/lib/posix/stdlib/strtold.c [ec18957a:d43c117] in mainline
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uspace/lib/posix/stdlib/strtold.c (modified) (14 diffs)
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uspace/lib/posix/stdlib/strtold.c
rec18957a rd43c117 30 30 * @{ 31 31 */ 32 /** @file 32 /** @file Backend for floating point conversions. 33 33 */ 34 34 … … 46 46 #include "../strings.h" 47 47 #include "../errno.h" 48 #include "../limits.h" 49 50 // FIXME: #include <float.h> 48 51 49 52 #ifndef HUGE_VALL … … 52 55 53 56 #ifndef abs 54 #define abs(x) ((x < 0) ? -x : x) 55 #endif 56 57 // TODO: clean up, documentation 58 59 // FIXME: ensure it builds and works on all platforms 60 61 const int max_small_pow5 = 15; 62 63 /* The value at index i is approximately 5**i. */ 64 long double small_pow5[] = { 65 0x1P0, 66 0x5P0, 67 0x19P0, 68 0x7dP0, 69 0x271P0, 70 0xc35P0, 71 0x3d09P0, 72 0x1312dP0, 73 0x5f5e1P0, 74 0x1dcd65P0, 75 0x9502f9P0, 76 0x2e90eddP0, 77 0xe8d4a51P0, 78 0x48c27395P0, 79 0x16bcc41e9P0, 80 0x71afd498dP0 57 #define abs(x) (((x) < 0) ? -(x) : (x)) 58 #endif 59 60 /* If the constants are not defined, use double precision as default. */ 61 #ifndef LDBL_MANT_DIG 62 #define LDBL_MANT_DIG 53 63 #endif 64 #ifndef LDBL_MAX_EXP 65 #define LDBL_MAX_EXP 1024 66 #endif 67 #ifndef LDBL_MIN_EXP 68 #define LDBL_MIN_EXP (-1021) 69 #endif 70 #ifndef LDBL_DIG 71 #define LDBL_DIG 15 72 #endif 73 #ifndef LDBL_MIN 74 #define LDBL_MIN 2.2250738585072014E-308 75 #endif 76 77 /* power functions ************************************************************/ 78 79 #if LDBL_MAX_EXP >= 16384 80 const int MAX_POW5 = 12; 81 #else 82 const int MAX_POW5 = 8; 83 #endif 84 85 /* The value at index i is approximately 5**(2**i). */ 86 long double pow5[] = { 87 0x5p0l, 88 0x19p0l, 89 0x271p0l, 90 0x5F5E1p0l, 91 0x2386F26FC1p0l, 92 0x4EE2D6D415B85ACEF81p0l, 93 0x184F03E93FF9F4DAA797ED6E38ED6p36l, 94 0x127748F9301D319BF8CDE66D86D62p185l, 95 0x154FDD7F73BF3BD1BBB77203731FDp482l, 96 #if LDBL_MAX_EXP >= 16384 97 0x1C633415D4C1D238D98CAB8A978A0p1076l, 98 0x192ECEB0D02EA182ECA1A7A51E316p2265l, 99 0x13D1676BB8A7ABBC94E9A519C6535p4643l, 100 0x188C0A40514412F3592982A7F0094p9398l, 101 #endif 81 102 }; 82 103 83 /* The value at index i is approximately 5**(2**i). */ 84 long double large_pow5[] = { 85 0x5P0l, 86 0x19P0l, 87 0x271P0l, 88 0x5f5e1P0l, 89 0x2386f26fc1P0l, 90 0x4ee2d6d415b85acef81P0l, 91 0x184f03e93ff9f4daa797ed6e38ed64bf6a1f01P0l, 92 0x24ee91f2603a6337f19bccdb0dac404dc08d3cff5ecP128l, 93 0x553f75fdcefcef46eeddcP512l, 94 0x1c633415d4c1d238d98cab8a978a0b1f138cb07303P1024l, 95 0x325d9d61a05d4305d9434f4a3c62d433949ae6209d492P2200l, 96 0x9e8b3b5dc53d5de4a74d28ce329ace526a3197bbebe3034f77154ce2bcba1964P4500l, 97 0x6230290145104bcd64a60a9fc025254932bb0fd922271133eeae7P9300l 98 }; 104 #if LDBL_MAX_EXP >= 16384 105 const int MAX_POW2 = 15; 106 #else 107 const int MAX_POW2 = 9; 108 #endif 99 109 100 110 /* Powers of two. */ … … 110 120 0x1P256l, 111 121 0x1P512l, 122 #if LDBL_MAX_EXP >= 16384 112 123 0x1P1024l, 113 124 0x1P2048l, 114 125 0x1P4096l, 115 0x1P8192l 126 0x1P8192l, 127 #endif 116 128 }; 117 129 118 static inline bool out_of_range(long double num)119 {120 return num == 0.0l || num == HUGE_VALL;121 }122 123 130 /** 124 131 * Multiplies a number by a power of five. 125 * The result is not exact and may not be the best possible approximation. 126 * 127 * @param base Number to be multiplied. 128 * @param exponent Base 5 exponent. 129 * @return base multiplied by 5**exponent 130 */ 131 static long double mul_pow5(long double base, int exponent) 132 { 133 if (out_of_range(base)) { 134 return base; 135 } 136 137 if (abs(exponent) >> 13 != 0) { 132 * The result may be inexact and may not be the best possible approximation. 133 * 134 * @param mant Number to be multiplied. 135 * @param exp Base 5 exponent. 136 * @return mant multiplied by 5**exp 137 */ 138 static long double mul_pow5(long double mant, int exp) 139 { 140 if (mant == 0.0l || mant == HUGE_VALL) { 141 return mant; 142 } 143 144 if (abs(exp) >> (MAX_POW5 + 1) != 0) { 145 /* Too large exponent. */ 138 146 errno = ERANGE; 139 return exponent < 0 ? 0.0l : HUGE_VALL; 140 } 141 142 if (exponent < 0) { 143 exponent = -exponent; 144 base /= small_pow5[exponent & 0xF]; 145 for (int i = 4; i < 13; ++i) { 146 if (((exponent >> i) & 1) != 0) { 147 base /= large_pow5[i]; 148 if (out_of_range(base)) { 147 return exp < 0 ? LDBL_MIN : HUGE_VALL; 148 } 149 150 if (exp < 0) { 151 exp = abs(exp); 152 for (int bit = 0; bit <= MAX_POW5; ++bit) { 153 /* Multiply by powers of five bit-by-bit. */ 154 if (((exp >> bit) & 1) != 0) { 155 mant /= pow5[bit]; 156 if (mant == 0.0l) { 157 /* Underflow. */ 158 mant = LDBL_MIN; 149 159 errno = ERANGE; 150 160 break; … … 153 163 } 154 164 } else { 155 base *= small_pow5[exponent & 0xF]; 156 for (int i = 4; i < 13; ++i) { 157 if (((exponent >> i) & 1) != 0) { 158 base *= large_pow5[i]; 159 if (out_of_range(base)) { 165 for (int bit = 0; bit <= MAX_POW5; ++bit) { 166 /* Multiply by powers of five bit-by-bit. */ 167 if (((exp >> bit) & 1) != 0) { 168 mant *= pow5[bit]; 169 if (mant == HUGE_VALL) { 170 /* Overflow. */ 160 171 errno = ERANGE; 161 172 break; … … 165 176 } 166 177 167 return base;168 } 169 170 /** 171 * Multiplies a number by a power of two. 172 * 173 * @param baseNumber to be multiplied.174 * @param exp onentBase 2 exponent.175 * @return base multiplied by 2**exponent176 */ 177 static long double mul_pow2(long double base, int exponent)178 { 179 if ( out_of_range(base)) {180 return base;181 } 182 183 if ( abs(exponent) >> 14 != 0) {178 return mant; 179 } 180 181 /** 182 * Multiplies a number by a power of two. This is always exact. 183 * 184 * @param mant Number to be multiplied. 185 * @param exp Base 2 exponent. 186 * @return mant multiplied by 2**exp. 187 */ 188 static long double mul_pow2(long double mant, int exp) 189 { 190 if (mant == 0.0l || mant == HUGE_VALL) { 191 return mant; 192 } 193 194 if (exp > LDBL_MAX_EXP || exp < LDBL_MIN_EXP) { 184 195 errno = ERANGE; 185 return exponent < 0 ? 0.0l : HUGE_VALL; 186 } 187 188 if (exponent < 0) { 189 exponent = -exponent; 190 for (int i = 0; i < 14; ++i) { 191 if (((exponent >> i) & 1) != 0) { 192 base /= pow2[i]; 193 if (out_of_range(base)) { 196 return exp < 0 ? LDBL_MIN : HUGE_VALL; 197 } 198 199 if (exp < 0) { 200 exp = abs(exp); 201 for (int i = 0; i <= MAX_POW2; ++i) { 202 if (((exp >> i) & 1) != 0) { 203 mant /= pow2[i]; 204 if (mant == 0.0l) { 205 mant = LDBL_MIN; 194 206 errno = ERANGE; 195 207 break; … … 198 210 } 199 211 } else { 200 for (int i = 0; i < 14; ++i) {201 if (((exp onent>> i) & 1) != 0) {202 base*= pow2[i];203 if ( out_of_range(base)) {212 for (int i = 0; i <= MAX_POW2; ++i) { 213 if (((exp >> i) & 1) != 0) { 214 mant *= pow2[i]; 215 if (mant == HUGE_VALL) { 204 216 errno = ERANGE; 205 217 break; … … 209 221 } 210 222 211 return base; 212 } 213 214 223 return mant; 224 } 225 226 /* end power functions ********************************************************/ 227 228 229 230 /** 231 * Convert decimal string representation of the floating point number. 232 * Function expects the string pointer to be already pointed at the first 233 * digit (i.e. leading optional sign was already consumed by the caller). 234 * 235 * @param sptr Pointer to the storage of the string pointer. Upon successful 236 * conversion, the string pointer is updated to point to the first 237 * unrecognized character. 238 * @return An approximate representation of the input floating-point number. 239 */ 215 240 static long double parse_decimal(const char **sptr) 216 241 { 217 // TODO: Use strtol(), at least for exponent. 242 assert(sptr != NULL); 243 assert (*sptr != NULL); 218 244 219 245 const int DEC_BASE = 10; 220 246 const char DECIMAL_POINT = '.'; 221 247 const char EXPONENT_MARK = 'e'; 222 /* The highest amount of digits that can be safely parsed 223 * before an overflow occurs. 224 */ 225 const int PARSE_DECIMAL_DIGS = 19; 226 227 /* significand */ 228 uint64_t significand = 0; 229 230 /* position in the input string */ 231 int i = 0; 248 249 const char *str = *sptr; 250 long double significand = 0; 251 long exponent = 0; 232 252 233 253 /* number of digits parsed so far */ 234 254 int parsed_digits = 0; 235 236 int exponent = 0; 237 238 const char *str = *sptr; 239 240 /* digits before decimal point */ 241 while (isdigit(str[i])) { 242 if (parsed_digits == 0 && str[i] == '0') { 255 bool after_decimal = false; 256 257 while (isdigit(*str) || (!after_decimal && *str == DECIMAL_POINT)) { 258 if (*str == DECIMAL_POINT) { 259 after_decimal = true; 260 str++; 261 continue; 262 } 263 264 if (parsed_digits == 0 && *str == '0') { 243 265 /* Nothing, just skip leading zeros. */ 244 } else if (parsed_digits < PARSE_DECIMAL_DIGS) { 245 significand *= DEC_BASE; 246 significand += str[i] - '0'; 266 } else if (parsed_digits < LDBL_DIG) { 267 significand = significand * DEC_BASE + (*str - '0'); 247 268 parsed_digits++; 248 269 } else { … … 250 271 } 251 272 252 i++; 253 } 254 255 if (str[i] == DECIMAL_POINT) { 256 i++; 257 258 /* digits after decimal point */ 259 while (isdigit(str[i])) { 260 if (parsed_digits == 0 && str[i] == '0') { 261 /* Skip leading zeros and decrement exponent. */ 262 exponent--; 263 } else if (parsed_digits < PARSE_DECIMAL_DIGS) { 264 significand *= DEC_BASE; 265 significand += str[i] - '0'; 266 exponent--; 267 parsed_digits++; 268 } else { 269 /* ignore */ 270 } 271 272 i++; 273 } 273 if (after_decimal) { 274 /* Decrement exponent if we are parsing the fractional part. */ 275 exponent--; 276 } 277 278 str++; 274 279 } 275 280 276 281 /* exponent */ 277 if (tolower(str[i]) == EXPONENT_MARK) { 278 i++; 279 280 bool negative = false; 281 int exp = 0; 282 283 switch (str[i]) { 284 case '-': 285 negative = true; 286 /* fallthrough */ 287 case '+': 288 i++; 289 } 290 291 while (isdigit(str[i])) { 292 if (exp < 65536) { 293 exp *= DEC_BASE; 294 exp += str[i] - '0'; 295 } 296 297 i++; 298 } 299 300 if (negative) { 301 exp = -exp; 302 } 303 304 exponent += exp; 305 } 306 307 long double result = (long double) significand; 308 result = mul_pow5(result, exponent); 309 if (result != HUGE_VALL) { 310 result = mul_pow2(result, exponent); 311 } 312 313 *sptr = &str[i]; 314 return result; 315 } 316 282 if (tolower(*str) == EXPONENT_MARK) { 283 str++; 284 285 /* Returns MIN/MAX value on error, which is ok. */ 286 long exp = strtol(str, (char **) &str, DEC_BASE); 287 288 if (exponent > 0 && exp > LONG_MAX - exponent) { 289 exponent = LONG_MAX; 290 } else if (exponent < 0 && exp < LONG_MIN - exponent) { 291 exponent = LONG_MIN; 292 } else { 293 exponent += exp; 294 } 295 } 296 297 *sptr = str; 298 299 /* Return multiplied by a power of ten. */ 300 return mul_pow2(mul_pow5(significand, exponent), exponent); 301 } 302 303 /** 304 * Derive a hexadecimal digit from its character representation. 305 * 306 * @param ch Character representation of the hexadecimal digit. 307 * @return Digit value represented by an integer. 308 */ 317 309 static inline int hex_value(char ch) 318 310 { … … 325 317 326 318 /** 327 * @param val Integer value. 328 * @return How many leading zero bits there are. (Maximum is 3) 329 */ 330 static inline int leading_zeros(uint64_t val) 331 { 332 for (int i = 3; i > 0; --i) { 333 if ((val >> (64 - i)) == 0) { 334 return i; 335 } 336 } 337 338 return 0; 339 } 340 319 * Convert hexadecimal string representation of the floating point number. 320 * Function expects the string pointer to be already pointed at the first 321 * digit (i.e. leading optional sign and 0x prefix were already consumed 322 * by the caller). 323 * 324 * @param sptr Pointer to the storage of the string pointer. Upon successful 325 * conversion, the string pointer is updated to point to the first 326 * unrecognized character. 327 * @return Representation of the input floating-point number. 328 */ 341 329 static long double parse_hexadecimal(const char **sptr) 342 330 { 343 // TODO: Use strtol(), at least for exponent. 344 345 /* this function currently always rounds to zero */ 346 // TODO: honor rounding mode 331 assert(sptr != NULL && *sptr != NULL); 347 332 348 333 const int DEC_BASE = 10; … … 350 335 const char DECIMAL_POINT = '.'; 351 336 const char EXPONENT_MARK = 'p'; 352 /* The highest amount of digits that can be safely parsed353 * before an overflow occurs.354 */355 const int PARSE_HEX_DIGS = 16;356 357 /* significand */358 uint64_t significand = 0;359 360 /* position in the input string */361 int i = 0;362 363 /* number of digits parsed so far */364 int parsed_digits = 0;365 366 int exponent = 0;367 337 368 338 const char *str = *sptr; 369 370 /* digits before decimal point */ 371 while (posix_isxdigit(str[i])) { 372 if (parsed_digits == 0 && str[i] == '0') { 339 long double significand = 0; 340 long exponent = 0; 341 342 /* number of bits parsed so far */ 343 int parsed_bits = 0; 344 bool after_decimal = false; 345 346 while (posix_isxdigit(*str) || (!after_decimal && *str == DECIMAL_POINT)) { 347 if (*str == DECIMAL_POINT) { 348 after_decimal = true; 349 str++; 350 continue; 351 } 352 353 if (parsed_bits == 0 && *str == '0') { 373 354 /* Nothing, just skip leading zeros. */ 374 } else if (parsed_digits < PARSE_HEX_DIGS) { 375 significand *= HEX_BASE; 376 significand += hex_value(str[i]); 377 parsed_digits++; 378 } else if (parsed_digits == PARSE_HEX_DIGS) { 379 /* The first digit may have had leading zeros, 380 * so we need to parse one more digit and shift 381 * the value accordingly. 382 */ 383 384 int zeros = leading_zeros(significand); 385 significand = (significand << zeros) | 386 (hex_value(str[i]) >> (4 - zeros)); 387 388 exponent += (4 - zeros); 389 parsed_digits++; 355 } else if (parsed_bits <= LDBL_MANT_DIG) { 356 significand = significand * HEX_BASE + hex_value(*str); 357 parsed_bits += 4; 390 358 } else { 391 359 exponent += 4; 392 360 } 393 361 394 i++; 395 } 396 397 if (str[i] == DECIMAL_POINT) { 398 i++; 399 400 /* digits after decimal point */ 401 while (posix_isxdigit(str[i])) { 402 if (parsed_digits == 0 && str[i] == '0') { 403 /* Skip leading zeros and decrement exponent. */ 404 exponent -= 4; 405 } else if (parsed_digits < PARSE_HEX_DIGS) { 406 significand *= HEX_BASE; 407 significand += hex_value(str[i]); 408 exponent -= 4; 409 parsed_digits++; 410 } else if (parsed_digits == PARSE_HEX_DIGS) { 411 /* The first digit may have had leading zeros, 412 * so we need to parse one more digit and shift 413 * the value accordingly. 414 */ 415 416 int zeros = leading_zeros(significand); 417 significand = (significand << zeros) | 418 (hex_value(str[i]) >> (4 - zeros)); 419 420 exponent -= zeros; 421 parsed_digits++; 422 } else { 423 /* ignore */ 424 } 425 426 i++; 427 } 362 if (after_decimal) { 363 exponent -= 4; 364 } 365 366 str++; 428 367 } 429 368 430 369 /* exponent */ 431 if (tolower(str[i]) == EXPONENT_MARK) { 432 i++; 433 434 bool negative = false; 435 int exp = 0; 436 437 switch (str[i]) { 438 case '-': 439 negative = true; 440 /* fallthrough */ 441 case '+': 442 i++; 443 } 444 445 while (isdigit(str[i])) { 446 if (exp < 65536) { 447 exp *= DEC_BASE; 448 exp += str[i] - '0'; 449 } 450 451 i++; 452 } 453 454 if (negative) { 455 exp = -exp; 456 } 457 458 exponent += exp; 459 } 460 461 long double result = (long double) significand; 462 result = mul_pow2(result, exponent); 463 464 *sptr = &str[i]; 465 return result; 370 if (tolower(*str) == EXPONENT_MARK) { 371 str++; 372 373 /* Returns MIN/MAX value on error, which is ok. */ 374 long exp = strtol(str, (char **) &str, DEC_BASE); 375 376 if (exponent > 0 && exp > LONG_MAX - exponent) { 377 exponent = LONG_MAX; 378 } else if (exponent < 0 && exp < LONG_MIN - exponent) { 379 exponent = LONG_MIN; 380 } else { 381 exponent += exp; 382 } 383 } 384 385 *sptr = str; 386 387 /* Return multiplied by a power of two. */ 388 return mul_pow2(significand, exponent); 466 389 } 467 390 … … 478 401 * @param nptr Input string. 479 402 * @param endptr If non-NULL, *endptr is set to the position of the first 480 * unrecognized character.403 * unrecognized character. 481 404 * @return An approximate representation of the input floating-point number. 482 405 */ … … 512 435 513 436 if (endptr != NULL) { 514 *endptr = (char *) &nptr[i + 3];515 } 516 errno = E RANGE;517 return negative ? -0.0l : +0.0l;437 *endptr = (char *) nptr; 438 } 439 errno = EINVAL; 440 return 0; 518 441 } 519 442 … … 567 490 /** @} 568 491 */ 569
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