3 * Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
4 * 2002, 2003, 2004, 2005, 2006, 2007, 2008 by Larry Wall and others
6 * You may distribute under the terms of either the GNU General Public
7 * License or the Artistic License, as specified in the README file.
12 * "That only makes eleven (plus one mislaid) and not fourteen,
13 * unless wizards count differently to other people." --Beorn
15 * [p.115 of _The Hobbit_: "Queer Lodgings"]
19 =head1 Numeric functions
23 This file contains all the stuff needed by perl for manipulating numeric
24 values, including such things as replacements for the OS's atof() function
29 #define PERL_IN_NUMERIC_C
36 return f < I32_MIN ? (U32) I32_MIN : (U32)(I32) f;
39 if (f < U32_MAX_P1_HALF)
42 return ((U32) f) | (1 + U32_MAX >> 1);
47 return f > 0 ? U32_MAX : 0 /* NaN */;
54 return f < I32_MIN ? I32_MIN : (I32) f;
57 if (f < U32_MAX_P1_HALF)
60 return (I32)(((U32) f) | (1 + U32_MAX >> 1));
65 return f > 0 ? (I32)U32_MAX : 0 /* NaN */;
72 return f < IV_MIN ? IV_MIN : (IV) f;
75 /* For future flexibility allowing for sizeof(UV) >= sizeof(IV) */
76 if (f < UV_MAX_P1_HALF)
79 return (IV)(((UV) f) | (1 + UV_MAX >> 1));
84 return f > 0 ? (IV)UV_MAX : 0 /* NaN */;
91 return f < IV_MIN ? (UV) IV_MIN : (UV)(IV) f;
94 if (f < UV_MAX_P1_HALF)
97 return ((UV) f) | (1 + UV_MAX >> 1);
102 return f > 0 ? UV_MAX : 0 /* NaN */;
108 converts a string representing a binary number to numeric form.
110 On entry I<start> and I<*len> give the string to scan, I<*flags> gives
111 conversion flags, and I<result> should be NULL or a pointer to an NV.
112 The scan stops at the end of the string, or the first invalid character.
113 Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
114 invalid character will also trigger a warning.
115 On return I<*len> is set to the length of the scanned string,
116 and I<*flags> gives output flags.
118 If the value is <= C<UV_MAX> it is returned as a UV, the output flags are clear,
119 and nothing is written to I<*result>. If the value is > UV_MAX C<grok_bin>
120 returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
121 and writes the value to I<*result> (or the value is discarded if I<result>
124 The binary number may optionally be prefixed with "0b" or "b" unless
125 C<PERL_SCAN_DISALLOW_PREFIX> is set in I<*flags> on entry. If
126 C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the binary
127 number may use '_' characters to separate digits.
131 Not documented yet because experimental is C<PERL_SCAN_SILENT_NON_PORTABLE
132 which suppresses any message for non-portable numbers that are still valid
137 Perl_grok_bin(pTHX_ const char *start, STRLEN *len_p, I32 *flags, NV *result)
139 const char *s = start;
144 const UV max_div_2 = UV_MAX / 2;
145 const bool allow_underscores = cBOOL(*flags & PERL_SCAN_ALLOW_UNDERSCORES);
146 bool overflowed = FALSE;
149 PERL_ARGS_ASSERT_GROK_BIN;
151 if (!(*flags & PERL_SCAN_DISALLOW_PREFIX)) {
152 /* strip off leading b or 0b.
153 for compatibility silently suffer "b" and "0b" as valid binary
156 if (s[0] == 'b' || s[0] == 'B') {
160 else if (len >= 2 && s[0] == '0' && (s[1] == 'b' || s[1] == 'B')) {
167 for (; len-- && (bit = *s); s++) {
168 if (bit == '0' || bit == '1') {
169 /* Write it in this wonky order with a goto to attempt to get the
170 compiler to make the common case integer-only loop pretty tight.
171 With gcc seems to be much straighter code than old scan_bin. */
174 if (value <= max_div_2) {
175 value = (value << 1) | (bit - '0');
178 /* Bah. We're just overflowed. */
179 /* diag_listed_as: Integer overflow in %s number */
180 Perl_ck_warner_d(aTHX_ packWARN(WARN_OVERFLOW),
181 "Integer overflow in binary number");
183 value_nv = (NV) value;
186 /* If an NV has not enough bits in its mantissa to
187 * represent a UV this summing of small low-order numbers
188 * is a waste of time (because the NV cannot preserve
189 * the low-order bits anyway): we could just remember when
190 * did we overflow and in the end just multiply value_nv by the
192 value_nv += (NV)(bit - '0');
195 if (bit == '_' && len && allow_underscores && (bit = s[1])
196 && (bit == '0' || bit == '1'))
202 if (!(*flags & PERL_SCAN_SILENT_ILLDIGIT))
203 Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
204 "Illegal binary digit '%c' ignored", *s);
208 if ( ( overflowed && value_nv > 4294967295.0)
210 || (!overflowed && value > 0xffffffff
211 && ! (*flags & PERL_SCAN_SILENT_NON_PORTABLE))
214 Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE),
215 "Binary number > 0b11111111111111111111111111111111 non-portable");
222 *flags = PERL_SCAN_GREATER_THAN_UV_MAX;
231 converts a string representing a hex number to numeric form.
233 On entry I<start> and I<*len_p> give the string to scan, I<*flags> gives
234 conversion flags, and I<result> should be NULL or a pointer to an NV.
235 The scan stops at the end of the string, or the first invalid character.
236 Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
237 invalid character will also trigger a warning.
238 On return I<*len> is set to the length of the scanned string,
239 and I<*flags> gives output flags.
241 If the value is <= UV_MAX it is returned as a UV, the output flags are clear,
242 and nothing is written to I<*result>. If the value is > UV_MAX C<grok_hex>
243 returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
244 and writes the value to I<*result> (or the value is discarded if I<result>
247 The hex number may optionally be prefixed with "0x" or "x" unless
248 C<PERL_SCAN_DISALLOW_PREFIX> is set in I<*flags> on entry. If
249 C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the hex
250 number may use '_' characters to separate digits.
254 Not documented yet because experimental is C<PERL_SCAN_SILENT_NON_PORTABLE
255 which suppresses any message for non-portable numbers that are still valid
260 Perl_grok_hex(pTHX_ const char *start, STRLEN *len_p, I32 *flags, NV *result)
263 const char *s = start;
267 const UV max_div_16 = UV_MAX / 16;
268 const bool allow_underscores = cBOOL(*flags & PERL_SCAN_ALLOW_UNDERSCORES);
269 bool overflowed = FALSE;
271 PERL_ARGS_ASSERT_GROK_HEX;
273 if (!(*flags & PERL_SCAN_DISALLOW_PREFIX)) {
274 /* strip off leading x or 0x.
275 for compatibility silently suffer "x" and "0x" as valid hex numbers.
278 if (s[0] == 'x' || s[0] == 'X') {
282 else if (len >= 2 && s[0] == '0' && (s[1] == 'x' || s[1] == 'X')) {
289 for (; len-- && *s; s++) {
291 /* Write it in this wonky order with a goto to attempt to get the
292 compiler to make the common case integer-only loop pretty tight.
293 With gcc seems to be much straighter code than old scan_hex. */
296 if (value <= max_div_16) {
297 value = (value << 4) | XDIGIT_VALUE(*s);
300 /* Bah. We're just overflowed. */
301 /* diag_listed_as: Integer overflow in %s number */
302 Perl_ck_warner_d(aTHX_ packWARN(WARN_OVERFLOW),
303 "Integer overflow in hexadecimal number");
305 value_nv = (NV) value;
308 /* If an NV has not enough bits in its mantissa to
309 * represent a UV this summing of small low-order numbers
310 * is a waste of time (because the NV cannot preserve
311 * the low-order bits anyway): we could just remember when
312 * did we overflow and in the end just multiply value_nv by the
313 * right amount of 16-tuples. */
314 value_nv += (NV) XDIGIT_VALUE(*s);
317 if (*s == '_' && len && allow_underscores && s[1]
324 if (!(*flags & PERL_SCAN_SILENT_ILLDIGIT))
325 Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
326 "Illegal hexadecimal digit '%c' ignored", *s);
330 if ( ( overflowed && value_nv > 4294967295.0)
332 || (!overflowed && value > 0xffffffff
333 && ! (*flags & PERL_SCAN_SILENT_NON_PORTABLE))
336 Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE),
337 "Hexadecimal number > 0xffffffff non-portable");
344 *flags = PERL_SCAN_GREATER_THAN_UV_MAX;
353 converts a string representing an octal number to numeric form.
355 On entry I<start> and I<*len> give the string to scan, I<*flags> gives
356 conversion flags, and I<result> should be NULL or a pointer to an NV.
357 The scan stops at the end of the string, or the first invalid character.
358 Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
359 8 or 9 will also trigger a warning.
360 On return I<*len> is set to the length of the scanned string,
361 and I<*flags> gives output flags.
363 If the value is <= UV_MAX it is returned as a UV, the output flags are clear,
364 and nothing is written to I<*result>. If the value is > UV_MAX C<grok_oct>
365 returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
366 and writes the value to I<*result> (or the value is discarded if I<result>
369 If C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the octal
370 number may use '_' characters to separate digits.
374 Not documented yet because experimental is C<PERL_SCAN_SILENT_NON_PORTABLE>
375 which suppresses any message for non-portable numbers, but which are valid
380 Perl_grok_oct(pTHX_ const char *start, STRLEN *len_p, I32 *flags, NV *result)
382 const char *s = start;
386 const UV max_div_8 = UV_MAX / 8;
387 const bool allow_underscores = cBOOL(*flags & PERL_SCAN_ALLOW_UNDERSCORES);
388 bool overflowed = FALSE;
390 PERL_ARGS_ASSERT_GROK_OCT;
392 for (; len-- && *s; s++) {
394 /* Write it in this wonky order with a goto to attempt to get the
395 compiler to make the common case integer-only loop pretty tight.
399 if (value <= max_div_8) {
400 value = (value << 3) | OCTAL_VALUE(*s);
403 /* Bah. We're just overflowed. */
404 /* diag_listed_as: Integer overflow in %s number */
405 Perl_ck_warner_d(aTHX_ packWARN(WARN_OVERFLOW),
406 "Integer overflow in octal number");
408 value_nv = (NV) value;
411 /* If an NV has not enough bits in its mantissa to
412 * represent a UV this summing of small low-order numbers
413 * is a waste of time (because the NV cannot preserve
414 * the low-order bits anyway): we could just remember when
415 * did we overflow and in the end just multiply value_nv by the
416 * right amount of 8-tuples. */
417 value_nv += (NV) OCTAL_VALUE(*s);
420 if (*s == '_' && len && allow_underscores && isOCTAL(s[1])) {
425 /* Allow \octal to work the DWIM way (that is, stop scanning
426 * as soon as non-octal characters are seen, complain only if
427 * someone seems to want to use the digits eight and nine. Since we
428 * know it is not octal, then if isDIGIT, must be an 8 or 9). */
430 if (!(*flags & PERL_SCAN_SILENT_ILLDIGIT))
431 Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
432 "Illegal octal digit '%c' ignored", *s);
437 if ( ( overflowed && value_nv > 4294967295.0)
439 || (!overflowed && value > 0xffffffff
440 && ! (*flags & PERL_SCAN_SILENT_NON_PORTABLE))
443 Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE),
444 "Octal number > 037777777777 non-portable");
451 *flags = PERL_SCAN_GREATER_THAN_UV_MAX;
460 For backwards compatibility. Use C<grok_bin> instead.
464 For backwards compatibility. Use C<grok_hex> instead.
468 For backwards compatibility. Use C<grok_oct> instead.
474 Perl_scan_bin(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
477 I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
478 const UV ruv = grok_bin (start, &len, &flags, &rnv);
480 PERL_ARGS_ASSERT_SCAN_BIN;
483 return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
487 Perl_scan_oct(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
490 I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
491 const UV ruv = grok_oct (start, &len, &flags, &rnv);
493 PERL_ARGS_ASSERT_SCAN_OCT;
496 return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
500 Perl_scan_hex(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
503 I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
504 const UV ruv = grok_hex (start, &len, &flags, &rnv);
506 PERL_ARGS_ASSERT_SCAN_HEX;
509 return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
513 =for apidoc grok_numeric_radix
515 Scan and skip for a numeric decimal separator (radix).
520 Perl_grok_numeric_radix(pTHX_ const char **sp, const char *send)
522 #ifdef USE_LOCALE_NUMERIC
525 PERL_ARGS_ASSERT_GROK_NUMERIC_RADIX;
527 if (IN_LC(LC_NUMERIC)) {
528 DECLARE_STORE_LC_NUMERIC_SET_TO_NEEDED();
529 if (PL_numeric_radix_sv) {
531 const char * const radix = SvPV(PL_numeric_radix_sv, len);
532 if (*sp + len <= send && memEQ(*sp, radix, len)) {
534 RESTORE_LC_NUMERIC();
538 RESTORE_LC_NUMERIC();
540 /* always try "." if numeric radix didn't match because
541 * we may have data from different locales mixed */
544 PERL_ARGS_ASSERT_GROK_NUMERIC_RADIX;
546 if (*sp < send && **sp == '.') {
554 =for apidoc grok_number
556 Recognise (or not) a number. The type of the number is returned
557 (0 if unrecognised), otherwise it is a bit-ORed combination of
558 IS_NUMBER_IN_UV, IS_NUMBER_GREATER_THAN_UV_MAX, IS_NUMBER_NOT_INT,
559 IS_NUMBER_NEG, IS_NUMBER_INFINITY, IS_NUMBER_NAN (defined in perl.h).
561 If the value of the number can fit in a UV, it is returned in the *valuep
562 IS_NUMBER_IN_UV will be set to indicate that *valuep is valid, IS_NUMBER_IN_UV
563 will never be set unless *valuep is valid, but *valuep may have been assigned
564 to during processing even though IS_NUMBER_IN_UV is not set on return.
565 If valuep is NULL, IS_NUMBER_IN_UV will be set for the same cases as when
566 valuep is non-NULL, but no actual assignment (or SEGV) will occur.
568 IS_NUMBER_NOT_INT will be set with IS_NUMBER_IN_UV if trailing decimals were
569 seen (in which case *valuep gives the true value truncated to an integer), and
570 IS_NUMBER_NEG if the number is negative (in which case *valuep holds the
571 absolute value). IS_NUMBER_IN_UV is not set if e notation was used or the
572 number is larger than a UV.
577 Perl_grok_number(pTHX_ const char *pv, STRLEN len, UV *valuep)
580 const char * const send = pv + len;
581 const UV max_div_10 = UV_MAX / 10;
582 const char max_mod_10 = UV_MAX % 10;
587 PERL_ARGS_ASSERT_GROK_NUMBER;
589 while (s < send && isSPACE(*s))
593 } else if (*s == '-') {
595 numtype = IS_NUMBER_NEG;
603 /* next must be digit or the radix separator or beginning of infinity */
605 /* UVs are at least 32 bits, so the first 9 decimal digits cannot
608 /* This construction seems to be more optimiser friendly.
609 (without it gcc does the isDIGIT test and the *s - '0' separately)
610 With it gcc on arm is managing 6 instructions (6 cycles) per digit.
611 In theory the optimiser could deduce how far to unroll the loop
612 before checking for overflow. */
614 int digit = *s - '0';
615 if (digit >= 0 && digit <= 9) {
616 value = value * 10 + digit;
619 if (digit >= 0 && digit <= 9) {
620 value = value * 10 + digit;
623 if (digit >= 0 && digit <= 9) {
624 value = value * 10 + digit;
627 if (digit >= 0 && digit <= 9) {
628 value = value * 10 + digit;
631 if (digit >= 0 && digit <= 9) {
632 value = value * 10 + digit;
635 if (digit >= 0 && digit <= 9) {
636 value = value * 10 + digit;
639 if (digit >= 0 && digit <= 9) {
640 value = value * 10 + digit;
643 if (digit >= 0 && digit <= 9) {
644 value = value * 10 + digit;
646 /* Now got 9 digits, so need to check
647 each time for overflow. */
649 while (digit >= 0 && digit <= 9
650 && (value < max_div_10
651 || (value == max_div_10
652 && digit <= max_mod_10))) {
653 value = value * 10 + digit;
659 if (digit >= 0 && digit <= 9
662 skip the remaining digits, don't
663 worry about setting *valuep. */
666 } while (s < send && isDIGIT(*s));
668 IS_NUMBER_GREATER_THAN_UV_MAX;
688 numtype |= IS_NUMBER_IN_UV;
693 if (GROK_NUMERIC_RADIX(&s, send)) {
694 numtype |= IS_NUMBER_NOT_INT;
695 while (s < send && isDIGIT(*s)) /* optional digits after the radix */
699 else if (GROK_NUMERIC_RADIX(&s, send)) {
700 numtype |= IS_NUMBER_NOT_INT | IS_NUMBER_IN_UV; /* valuep assigned below */
701 /* no digits before the radix means we need digits after it */
702 if (s < send && isDIGIT(*s)) {
705 } while (s < send && isDIGIT(*s));
707 /* integer approximation is valid - it's 0. */
713 } else if (*s == 'I' || *s == 'i') {
714 s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
715 s++; if (s == send || (*s != 'F' && *s != 'f')) return 0;
716 s++; if (s < send && (*s == 'I' || *s == 'i')) {
717 s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
718 s++; if (s == send || (*s != 'I' && *s != 'i')) return 0;
719 s++; if (s == send || (*s != 'T' && *s != 't')) return 0;
720 s++; if (s == send || (*s != 'Y' && *s != 'y')) return 0;
724 } else if (*s == 'N' || *s == 'n') {
725 /* XXX TODO: There are signaling NaNs and quiet NaNs. */
726 s++; if (s == send || (*s != 'A' && *s != 'a')) return 0;
727 s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
734 numtype &= IS_NUMBER_NEG; /* Keep track of sign */
735 numtype |= IS_NUMBER_INFINITY | IS_NUMBER_NOT_INT;
737 numtype &= IS_NUMBER_NEG; /* Keep track of sign */
738 numtype |= IS_NUMBER_NAN | IS_NUMBER_NOT_INT;
739 } else if (s < send) {
740 /* we can have an optional exponent part */
741 if (*s == 'e' || *s == 'E') {
742 /* The only flag we keep is sign. Blow away any "it's UV" */
743 numtype &= IS_NUMBER_NEG;
744 numtype |= IS_NUMBER_NOT_INT;
746 if (s < send && (*s == '-' || *s == '+'))
748 if (s < send && isDIGIT(*s)) {
751 } while (s < send && isDIGIT(*s));
757 while (s < send && isSPACE(*s))
761 if (len == 10 && memEQ(pv, "0 but true", 10)) {
764 return IS_NUMBER_IN_UV;
770 S_mulexp10(NV value, I32 exponent)
782 /* On OpenVMS VAX we by default use the D_FLOAT double format,
783 * and that format does not have *easy* capabilities [1] for
784 * overflowing doubles 'silently' as IEEE fp does. We also need
785 * to support G_FLOAT on both VAX and Alpha, and though the exponent
786 * range is much larger than D_FLOAT it still doesn't do silent
787 * overflow. Therefore we need to detect early whether we would
788 * overflow (this is the behaviour of the native string-to-float
789 * conversion routines, and therefore of native applications, too).
791 * [1] Trying to establish a condition handler to trap floating point
792 * exceptions is not a good idea. */
794 /* In UNICOS and in certain Cray models (such as T90) there is no
795 * IEEE fp, and no way at all from C to catch fp overflows gracefully.
796 * There is something you can do if you are willing to use some
797 * inline assembler: the instruction is called DFI-- but that will
798 * disable *all* floating point interrupts, a little bit too large
799 * a hammer. Therefore we need to catch potential overflows before
802 #if ((defined(VMS) && !defined(_IEEE_FP)) || defined(_UNICOS)) && defined(NV_MAX_10_EXP)
804 const NV exp_v = log10(value);
805 if (exponent >= NV_MAX_10_EXP || exponent + exp_v >= NV_MAX_10_EXP)
808 if (-(exponent + exp_v) >= NV_MAX_10_EXP)
810 while (-exponent >= NV_MAX_10_EXP) {
811 /* combination does not overflow, but 10^(-exponent) does */
821 exponent = -exponent;
823 /* for something like 1234 x 10^-309, the action of calculating
824 * the intermediate value 10^309 then returning 1234 / (10^309)
825 * will fail, since 10^309 becomes infinity. In this case try to
826 * refactor it as 123 / (10^308) etc.
828 while (value && exponent > NV_MAX_10_EXP) {
834 for (bit = 1; exponent; bit <<= 1) {
835 if (exponent & bit) {
838 /* Floating point exceptions are supposed to be turned off,
839 * but if we're obviously done, don't risk another iteration.
841 if (exponent == 0) break;
845 return negative ? value / result : value * result;
849 Perl_my_atof(pTHX_ const char* s)
852 #ifdef USE_LOCALE_NUMERIC
855 PERL_ARGS_ASSERT_MY_ATOF;
858 DECLARE_STORE_LC_NUMERIC_SET_TO_NEEDED();
859 if (PL_numeric_radix_sv && IN_LC(LC_NUMERIC)) {
860 const char *standard = NULL, *local = NULL;
861 bool use_standard_radix;
863 /* Look through the string for the first thing that looks like a
864 * decimal point: either the value in the current locale or the
865 * standard fallback of '.'. The one which appears earliest in the
866 * input string is the one that we should have atof look for. Note
867 * that we have to determine this beforehand because on some
868 * systems, Perl_atof2 is just a wrapper around the system's atof.
870 standard = strchr(s, '.');
871 local = strstr(s, SvPV_nolen(PL_numeric_radix_sv));
873 use_standard_radix = standard && (!local || standard < local);
875 if (use_standard_radix)
876 SET_NUMERIC_STANDARD();
880 if (use_standard_radix)
885 RESTORE_LC_NUMERIC();
894 Perl_my_atof2(pTHX_ const char* orig, NV* value)
896 NV result[3] = {0.0, 0.0, 0.0};
897 const char* s = orig;
899 UV accumulator[2] = {0,0}; /* before/after dp */
901 const char* send = s + strlen(orig) - 1;
903 I32 exp_adjust[2] = {0,0};
904 I32 exp_acc[2] = {-1, -1};
905 /* the current exponent adjust for the accumulators */
910 I32 sig_digits = 0; /* noof significant digits seen so far */
912 PERL_ARGS_ASSERT_MY_ATOF2;
914 /* There is no point in processing more significant digits
915 * than the NV can hold. Note that NV_DIG is a lower-bound value,
916 * while we need an upper-bound value. We add 2 to account for this;
917 * since it will have been conservative on both the first and last digit.
918 * For example a 32-bit mantissa with an exponent of 4 would have
919 * exact values in the set
927 * where for the purposes of calculating NV_DIG we would have to discount
928 * both the first and last digit, since neither can hold all values from
929 * 0..9; but for calculating the value we must examine those two digits.
931 #ifdef MAX_SIG_DIG_PLUS
932 /* It is not necessarily the case that adding 2 to NV_DIG gets all the
933 possible digits in a NV, especially if NVs are not IEEE compliant
934 (e.g., long doubles on IRIX) - Allen <allens@cpan.org> */
935 # define MAX_SIG_DIGITS (NV_DIG+MAX_SIG_DIG_PLUS)
937 # define MAX_SIG_DIGITS (NV_DIG+2)
940 /* the max number we can accumulate in a UV, and still safely do 10*N+9 */
941 #define MAX_ACCUMULATE ( (UV) ((UV_MAX - 9)/10))
943 /* leading whitespace */
956 /* punt to strtod for NaN/Inf; if no support for it there, tough luck */
959 if (*s == 'n' || *s == 'N' || *s == 'i' || *s == 'I') {
960 const char *p = negative ? s - 1 : s;
963 rslt = strtod(p, &endp);
971 /* we accumulate digits into an integer; when this becomes too
972 * large, we add the total to NV and start again */
982 /* don't start counting until we see the first significant
983 * digit, eg the 5 in 0.00005... */
984 if (!sig_digits && digit == 0)
987 if (++sig_digits > MAX_SIG_DIGITS) {
988 /* limits of precision reached */
990 ++accumulator[seen_dp];
991 } else if (digit == 5) {
992 if (old_digit % 2) { /* round to even - Allen */
993 ++accumulator[seen_dp];
1001 /* skip remaining digits */
1002 while (isDIGIT(*s)) {
1008 /* warn of loss of precision? */
1011 if (accumulator[seen_dp] > MAX_ACCUMULATE) {
1012 /* add accumulator to result and start again */
1013 result[seen_dp] = S_mulexp10(result[seen_dp],
1015 + (NV)accumulator[seen_dp];
1016 accumulator[seen_dp] = 0;
1017 exp_acc[seen_dp] = 0;
1019 accumulator[seen_dp] = accumulator[seen_dp] * 10 + digit;
1023 else if (!seen_dp && GROK_NUMERIC_RADIX(&s, send)) {
1025 if (sig_digits > MAX_SIG_DIGITS) {
1028 } while (isDIGIT(*s));
1037 result[0] = S_mulexp10(result[0], exp_acc[0]) + (NV)accumulator[0];
1039 result[1] = S_mulexp10(result[1], exp_acc[1]) + (NV)accumulator[1];
1042 if (seen_digit && (*s == 'e' || *s == 'E')) {
1043 bool expnegative = 0;
1054 exponent = exponent * 10 + (*s++ - '0');
1056 exponent = -exponent;
1061 /* now apply the exponent */
1064 result[2] = S_mulexp10(result[0],exponent+exp_adjust[0])
1065 + S_mulexp10(result[1],exponent-exp_adjust[1]);
1067 result[2] = S_mulexp10(result[0],exponent+exp_adjust[0]);
1070 /* now apply the sign */
1072 result[2] = -result[2];
1073 #endif /* USE_PERL_ATOF */
1078 #if ! defined(HAS_MODFL) && defined(HAS_AINTL) && defined(HAS_COPYSIGNL)
1080 Perl_my_modfl(long double x, long double *ip)
1083 return (x == *ip ? copysignl(0.0L, x) : x - *ip);
1087 #if ! defined(HAS_FREXPL) && defined(HAS_ILOGBL) && defined(HAS_SCALBNL)
1089 Perl_my_frexpl(long double x, int *e) {
1090 *e = x == 0.0L ? 0 : ilogbl(x) + 1;
1091 return (scalbnl(x, -*e));
1096 =for apidoc Perl_signbit
1098 Return a non-zero integer if the sign bit on an NV is set, and 0 if
1101 If Configure detects this system has a signbit() that will work with
1102 our NVs, then we just use it via the #define in perl.h. Otherwise,
1103 fall back on this implementation. As a first pass, this gets everything
1104 right except -0.0. Alas, catching -0.0 is the main use for this function,
1105 so this is not too helpful yet. Still, at least we have the scaffolding
1106 in place to support other systems, should that prove useful.
1109 Configure notes: This function is called 'Perl_signbit' instead of a
1110 plain 'signbit' because it is easy to imagine a system having a signbit()
1111 function or macro that doesn't happen to work with our particular choice
1112 of NVs. We shouldn't just re-#define signbit as Perl_signbit and expect
1113 the standard system headers to be happy. Also, this is a no-context
1114 function (no pTHX_) because Perl_signbit() is usually re-#defined in
1115 perl.h as a simple macro call to the system's signbit().
1116 Users should just always call Perl_signbit().
1120 #if !defined(HAS_SIGNBIT)
1122 Perl_signbit(NV x) {
1123 return (x < 0.0) ? 1 : 0;
1129 * c-indentation-style: bsd
1131 * indent-tabs-mode: nil
1134 * ex: set ts=8 sts=4 sw=4 et: