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tinystdio: Add strtold implementation
This supports both 80- and 128- bit long double types. This patch also disables building strtold and friends from stdlib. Signed-off-by: Keith Packard <[email protected]>
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| Original file line number | Diff line number | Diff line change |
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| /* Copyright (c) 2002-2005 Michael Stumpf <[email protected]> | ||
| Copyright (c) 2006,2008 Dmitry Xmelkov | ||
| All rights reserved. | ||
| Redistribution and use in source and binary forms, with or without | ||
| modification, are permitted provided that the following conditions are met: | ||
| * Redistributions of source code must retain the above copyright | ||
| notice, this list of conditions and the following disclaimer. | ||
| * Redistributions in binary form must reproduce the above copyright | ||
| notice, this list of conditions and the following disclaimer in | ||
| the documentation and/or other materials provided with the | ||
| distribution. | ||
| * Neither the name of the copyright holders nor the names of | ||
| contributors may be used to endorse or promote products derived | ||
| from this software without specific prior written permission. | ||
| THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | ||
| AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | ||
| IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | ||
| ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE | ||
| LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | ||
| CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | ||
| SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | ||
| INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | ||
| CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | ||
| ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | ||
| POSSIBILITY OF SUCH DAMAGE. */ | ||
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| /* $Id: strtod.c 2191 2010-11-05 13:45:57Z arcanum $ */ | ||
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| #include <ctype.h> | ||
| #include <errno.h> | ||
| #include <limits.h> | ||
| #include <math.h> /* INFINITY, NAN */ | ||
| #include <string.h> | ||
| #include <stdlib.h> | ||
| #include <inttypes.h> | ||
| #include <stdbool.h> | ||
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| #define NPOW_10 13 | ||
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| static const long double pwr_p10 [NPOW_10] = { | ||
| 1e+1L, 1e+2L, 1e+4L, 1e+8L, 1e+16L, 1e+32L, 1e+64L, 1e+128L, 1e+256L, 1e+512L, 1e+1024L, 1e+2048L, 1e+4096L | ||
| }; | ||
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| static const long double pwr_m10 [NPOW_10] = { | ||
| 1e-1L, 1e-2L, 1e-4L, 1e-8L, 1e-16L, 1e-32L, 1e-64L, 1e-128L, 1e-256L, 1e-512L, 1e-1024L, 1e-2048L, 1e-4096L | ||
| }; | ||
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| /* PSTR() is not used to save 1 byte per string: '\0' at the tail. */ | ||
| static const char pstr_inf[] = {'I','N','F'}; | ||
| static const char pstr_inity[] = {'I','N','I','T','Y'}; | ||
| static const char pstr_nan[] = {'N','A','N'}; | ||
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| /** The strtold() function converts the initial portion of the string pointed | ||
| to by \a nptr to long double representation. | ||
| The expected form of the string is an optional plus ( \c '+' ) or minus | ||
| sign ( \c '-' ) followed by a sequence of digits optionally containing | ||
| a decimal-point character, optionally followed by an exponent. An | ||
| exponent consists of an \c 'E' or \c 'e', followed by an optional plus | ||
| or minus sign, followed by a sequence of digits. | ||
| Leading white-space characters in the string are skipped. | ||
| The strtold() function returns the converted value, if any. | ||
| If \a endptr is not \c NULL, a pointer to the character after the last | ||
| character used in the conversion is stored in the location referenced by | ||
| \a endptr. | ||
| If no conversion is performed, zero is returned and the value of | ||
| \a nptr is stored in the location referenced by \a endptr. | ||
| If the correct value would cause overflow, plus or minus \c INFINITY is | ||
| returned (according to the sign of the value), and \c ERANGE is stored | ||
| in \c errno. If the correct value would cause underflow, zero is | ||
| returned and \c ERANGE is stored in \c errno. | ||
| */ | ||
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| #ifdef __SIZEOF_INT128__ | ||
| typedef __uint128_t _u128; | ||
| #define _u128_plus_64(a,b) ((a) + (b)) | ||
| #define _u128_plus(a,b) ((a) + (b)) | ||
| #define _u128_times_10(a) ((a) * 10) | ||
| #define _u128_to_ld(a) ((long double) (a)) | ||
| #define _u128_oflow(a) ((a) >= (((((_u128) 0xffffffffffffffffULL) << 64) | 0xffffffffffffffffULL) - 9 / 10)) | ||
| #define _u128_zero (_u128) 0 | ||
| #else | ||
| typedef struct { | ||
| uint64_t hi, lo; | ||
| } _u128; | ||
| #define _u128_zero (_u128) { 0, 0 } | ||
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| static _u128 | ||
| _u128_plus_64(_u128 a, uint64_t b) | ||
| { | ||
| _u128 v; | ||
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| v.lo = a.lo + b; | ||
| v.hi = a.hi; | ||
| if (v.lo < a.lo) | ||
| v.hi++; | ||
| return v; | ||
| } | ||
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| static _u128 | ||
| _u128_plus(_u128 a, _u128 b) | ||
| { | ||
| _u128 v; | ||
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| v.lo = a.lo + b.lo; | ||
| v.hi = a.hi + b.hi; | ||
| if (v.lo < a.lo) | ||
| v.hi++; | ||
| return v; | ||
| } | ||
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| static _u128 | ||
| _u128_lshift(_u128 a, int amt) | ||
| { | ||
| _u128 v; | ||
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| v.lo = a.lo << amt; | ||
| v.hi = (a.lo >> (64 - amt)) | (a.hi << amt); | ||
| return v; | ||
| } | ||
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| static _u128 | ||
| _u128_times_10(_u128 a) | ||
| { | ||
| return _u128_plus(_u128_lshift(a, 3), _u128_lshift(a, 1)); | ||
| } | ||
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| static long double | ||
| _u128_to_ld(_u128 a) | ||
| { | ||
| return (long double) a.hi * ((long double) (1LL << 32) * (long double) (1LL << 32)) + (long double) a.lo; | ||
| } | ||
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| static bool | ||
| _u128_oflow(_u128 a) | ||
| { | ||
| return a.hi >= (0xffffffffffffffffULL - 9) / 10; | ||
| } | ||
| #endif | ||
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| long double | ||
| strtold (const char * nptr, char ** endptr) | ||
| { | ||
| _u128 u128; | ||
| long double flt; | ||
| unsigned char c; | ||
| int exp; | ||
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| unsigned char flag; | ||
| #define FL_MINUS 0x01 /* number is negative */ | ||
| #define FL_ANY 0x02 /* any digit was readed */ | ||
| #define FL_OVFL 0x04 /* overflow was */ | ||
| #define FL_DOT 0x08 /* decimal '.' was */ | ||
| #define FL_MEXP 0x10 /* exponent 'e' is neg. */ | ||
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| if (endptr) | ||
| *endptr = (char *)nptr; | ||
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| do { | ||
| c = *nptr++; | ||
| } while (isspace (c)); | ||
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| flag = 0; | ||
| if (c == '-') { | ||
| flag = FL_MINUS; | ||
| c = *nptr++; | ||
| } else if (c == '+') { | ||
| c = *nptr++; | ||
| } | ||
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| if (!strncmp (nptr - 1, pstr_inf, 3)) { | ||
| nptr += 2; | ||
| if (!strncmp (nptr, pstr_inity, 5)) | ||
| nptr += 5; | ||
| if (endptr) | ||
| *endptr = (char *)nptr; | ||
| return flag & FL_MINUS ? -INFINITY : +INFINITY; | ||
| } | ||
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| /* NAN() construction is not realised. | ||
| Length would be 3 characters only. */ | ||
| if (!strncmp (nptr - 1, pstr_nan, 3)) { | ||
| if (endptr) | ||
| *endptr = (char *)nptr + 2; | ||
| return __builtin_nanl(""); | ||
| } | ||
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| u128 = _u128_zero; | ||
| exp = 0; | ||
| while (1) { | ||
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| c -= '0'; | ||
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| if (c <= 9) { | ||
| flag |= FL_ANY; | ||
| if (flag & FL_OVFL) { | ||
| if (!(flag & FL_DOT)) | ||
| exp += 1; | ||
| } else { | ||
| if (flag & FL_DOT) | ||
| exp -= 1; | ||
| u128 = _u128_plus_64(_u128_times_10(u128), c); | ||
| if (_u128_oflow(u128)) | ||
| flag |= FL_OVFL; | ||
| } | ||
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| } else if (c == (('.'-'0') & 0xff) && !(flag & FL_DOT)) { | ||
| flag |= FL_DOT; | ||
| } else { | ||
| break; | ||
| } | ||
| c = *nptr++; | ||
| } | ||
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| if (c == (('e'-'0') & 0xff) || c == (('E'-'0') & 0xff)) | ||
| { | ||
| int i; | ||
| c = *nptr++; | ||
| i = 2; | ||
| if (c == '-') { | ||
| flag |= FL_MEXP; | ||
| c = *nptr++; | ||
| } else if (c == '+') { | ||
| c = *nptr++; | ||
| } else { | ||
| i = 1; | ||
| } | ||
| c -= '0'; | ||
| if (c > 9) { | ||
| nptr -= i; | ||
| } else { | ||
| i = 0; | ||
| do { | ||
| i = i * 10 + c; | ||
| c = *nptr++ - '0'; | ||
| } while (c <= 9); | ||
| if (flag & FL_MEXP) | ||
| i = -i; | ||
| exp += i; | ||
| } | ||
| } | ||
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| if ((flag & FL_ANY) && endptr) | ||
| *endptr = (char *)nptr - 1; | ||
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| flt = _u128_to_ld(u128); | ||
| if ((flag & FL_MINUS) && (flag & FL_ANY)) | ||
| flt = -flt; | ||
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| if (flt != 0) { | ||
| int pwr; | ||
| const long double *pptr; | ||
| if (exp < 0) { | ||
| pptr = (pwr_m10 + NPOW_10 - 1); | ||
| exp = -exp; | ||
| } else { | ||
| pptr = (pwr_p10 + NPOW_10 - 1); | ||
| } | ||
| for (pwr = 1 << (NPOW_10 - 1); pwr; pwr >>= 1) { | ||
| for (; exp >= pwr; exp -= pwr) { | ||
| flt *= *pptr; | ||
| } | ||
| pptr--; | ||
| } | ||
| // if (!isfinite(flt) || flt == 0) | ||
| // errno = ERANGE; | ||
| } | ||
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| return flt; | ||
| } |