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)
262 const char *s = start;
266 const UV max_div_16 = UV_MAX / 16;
267 const bool allow_underscores = cBOOL(*flags & PERL_SCAN_ALLOW_UNDERSCORES);
268 bool overflowed = FALSE;
270 PERL_ARGS_ASSERT_GROK_HEX;
272 if (!(*flags & PERL_SCAN_DISALLOW_PREFIX)) {
273 /* strip off leading x or 0x.
274 for compatibility silently suffer "x" and "0x" as valid hex numbers.
277 if (s[0] == 'x' || s[0] == 'X') {
281 else if (len >= 2 && s[0] == '0' && (s[1] == 'x' || s[1] == 'X')) {
288 for (; len-- && *s; s++) {
290 /* Write it in this wonky order with a goto to attempt to get the
291 compiler to make the common case integer-only loop pretty tight.
292 With gcc seems to be much straighter code than old scan_hex. */
295 if (value <= max_div_16) {
296 value = (value << 4) | XDIGIT_VALUE(*s);
299 /* Bah. We're just overflowed. */
300 /* diag_listed_as: Integer overflow in %s number */
301 Perl_ck_warner_d(aTHX_ packWARN(WARN_OVERFLOW),
302 "Integer overflow in hexadecimal number");
304 value_nv = (NV) value;
307 /* If an NV has not enough bits in its mantissa to
308 * represent a UV this summing of small low-order numbers
309 * is a waste of time (because the NV cannot preserve
310 * the low-order bits anyway): we could just remember when
311 * did we overflow and in the end just multiply value_nv by the
312 * right amount of 16-tuples. */
313 value_nv += (NV) XDIGIT_VALUE(*s);
316 if (*s == '_' && len && allow_underscores && s[1]
323 if (!(*flags & PERL_SCAN_SILENT_ILLDIGIT))
324 Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
325 "Illegal hexadecimal digit '%c' ignored", *s);
329 if ( ( overflowed && value_nv > 4294967295.0)
331 || (!overflowed && value > 0xffffffff
332 && ! (*flags & PERL_SCAN_SILENT_NON_PORTABLE))
335 Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE),
336 "Hexadecimal number > 0xffffffff non-portable");
343 *flags = PERL_SCAN_GREATER_THAN_UV_MAX;
352 converts a string representing an octal number to numeric form.
354 On entry I<start> and I<*len> give the string to scan, I<*flags> gives
355 conversion flags, and I<result> should be NULL or a pointer to an NV.
356 The scan stops at the end of the string, or the first invalid character.
357 Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
358 8 or 9 will also trigger a warning.
359 On return I<*len> is set to the length of the scanned string,
360 and I<*flags> gives output flags.
362 If the value is <= UV_MAX it is returned as a UV, the output flags are clear,
363 and nothing is written to I<*result>. If the value is > UV_MAX C<grok_oct>
364 returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
365 and writes the value to I<*result> (or the value is discarded if I<result>
368 If C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the octal
369 number may use '_' characters to separate digits.
373 Not documented yet because experimental is C<PERL_SCAN_SILENT_NON_PORTABLE>
374 which suppresses any message for non-portable numbers, but which are valid
379 Perl_grok_oct(pTHX_ const char *start, STRLEN *len_p, I32 *flags, NV *result)
381 const char *s = start;
385 const UV max_div_8 = UV_MAX / 8;
386 const bool allow_underscores = cBOOL(*flags & PERL_SCAN_ALLOW_UNDERSCORES);
387 bool overflowed = FALSE;
389 PERL_ARGS_ASSERT_GROK_OCT;
391 for (; len-- && *s; s++) {
393 /* Write it in this wonky order with a goto to attempt to get the
394 compiler to make the common case integer-only loop pretty tight.
398 if (value <= max_div_8) {
399 value = (value << 3) | OCTAL_VALUE(*s);
402 /* Bah. We're just overflowed. */
403 /* diag_listed_as: Integer overflow in %s number */
404 Perl_ck_warner_d(aTHX_ packWARN(WARN_OVERFLOW),
405 "Integer overflow in octal number");
407 value_nv = (NV) value;
410 /* If an NV has not enough bits in its mantissa to
411 * represent a UV this summing of small low-order numbers
412 * is a waste of time (because the NV cannot preserve
413 * the low-order bits anyway): we could just remember when
414 * did we overflow and in the end just multiply value_nv by the
415 * right amount of 8-tuples. */
416 value_nv += (NV) OCTAL_VALUE(*s);
419 if (*s == '_' && len && allow_underscores && isOCTAL(s[1])) {
424 /* Allow \octal to work the DWIM way (that is, stop scanning
425 * as soon as non-octal characters are seen, complain only if
426 * someone seems to want to use the digits eight and nine. Since we
427 * know it is not octal, then if isDIGIT, must be an 8 or 9). */
429 if (!(*flags & PERL_SCAN_SILENT_ILLDIGIT))
430 Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
431 "Illegal octal digit '%c' ignored", *s);
436 if ( ( overflowed && value_nv > 4294967295.0)
438 || (!overflowed && value > 0xffffffff
439 && ! (*flags & PERL_SCAN_SILENT_NON_PORTABLE))
442 Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE),
443 "Octal number > 037777777777 non-portable");
450 *flags = PERL_SCAN_GREATER_THAN_UV_MAX;
459 For backwards compatibility. Use C<grok_bin> instead.
463 For backwards compatibility. Use C<grok_hex> instead.
467 For backwards compatibility. Use C<grok_oct> instead.
473 Perl_scan_bin(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
476 I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
477 const UV ruv = grok_bin (start, &len, &flags, &rnv);
479 PERL_ARGS_ASSERT_SCAN_BIN;
482 return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
486 Perl_scan_oct(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
489 I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
490 const UV ruv = grok_oct (start, &len, &flags, &rnv);
492 PERL_ARGS_ASSERT_SCAN_OCT;
495 return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
499 Perl_scan_hex(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
502 I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
503 const UV ruv = grok_hex (start, &len, &flags, &rnv);
505 PERL_ARGS_ASSERT_SCAN_HEX;
508 return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
512 =for apidoc grok_numeric_radix
514 Scan and skip for a numeric decimal separator (radix).
519 Perl_grok_numeric_radix(pTHX_ const char **sp, const char *send)
521 #ifdef USE_LOCALE_NUMERIC
522 PERL_ARGS_ASSERT_GROK_NUMERIC_RADIX;
524 if (IN_LC(LC_NUMERIC)) {
525 DECLARE_STORE_LC_NUMERIC_SET_TO_NEEDED();
526 if (PL_numeric_radix_sv) {
528 const char * const radix = SvPV(PL_numeric_radix_sv, len);
529 if (*sp + len <= send && memEQ(*sp, radix, len)) {
531 RESTORE_LC_NUMERIC();
535 RESTORE_LC_NUMERIC();
537 /* always try "." if numeric radix didn't match because
538 * we may have data from different locales mixed */
541 PERL_ARGS_ASSERT_GROK_NUMERIC_RADIX;
543 if (*sp < send && **sp == '.') {
551 =for apidoc grok_number
553 Recognise (or not) a number. The type of the number is returned
554 (0 if unrecognised), otherwise it is a bit-ORed combination of
555 IS_NUMBER_IN_UV, IS_NUMBER_GREATER_THAN_UV_MAX, IS_NUMBER_NOT_INT,
556 IS_NUMBER_NEG, IS_NUMBER_INFINITY, IS_NUMBER_NAN (defined in perl.h).
558 If the value of the number can fit in a UV, it is returned in the *valuep
559 IS_NUMBER_IN_UV will be set to indicate that *valuep is valid, IS_NUMBER_IN_UV
560 will never be set unless *valuep is valid, but *valuep may have been assigned
561 to during processing even though IS_NUMBER_IN_UV is not set on return.
562 If valuep is NULL, IS_NUMBER_IN_UV will be set for the same cases as when
563 valuep is non-NULL, but no actual assignment (or SEGV) will occur.
565 IS_NUMBER_NOT_INT will be set with IS_NUMBER_IN_UV if trailing decimals were
566 seen (in which case *valuep gives the true value truncated to an integer), and
567 IS_NUMBER_NEG if the number is negative (in which case *valuep holds the
568 absolute value). IS_NUMBER_IN_UV is not set if e notation was used or the
569 number is larger than a UV.
574 Perl_grok_number(pTHX_ const char *pv, STRLEN len, UV *valuep)
577 const char * const send = pv + len;
578 const UV max_div_10 = UV_MAX / 10;
579 const char max_mod_10 = UV_MAX % 10;
584 PERL_ARGS_ASSERT_GROK_NUMBER;
586 while (s < send && isSPACE(*s))
590 } else if (*s == '-') {
592 numtype = IS_NUMBER_NEG;
600 /* next must be digit or the radix separator or beginning of infinity */
602 /* UVs are at least 32 bits, so the first 9 decimal digits cannot
605 /* This construction seems to be more optimiser friendly.
606 (without it gcc does the isDIGIT test and the *s - '0' separately)
607 With it gcc on arm is managing 6 instructions (6 cycles) per digit.
608 In theory the optimiser could deduce how far to unroll the loop
609 before checking for overflow. */
611 int digit = *s - '0';
612 if (digit >= 0 && digit <= 9) {
613 value = value * 10 + digit;
616 if (digit >= 0 && digit <= 9) {
617 value = value * 10 + digit;
620 if (digit >= 0 && digit <= 9) {
621 value = value * 10 + digit;
624 if (digit >= 0 && digit <= 9) {
625 value = value * 10 + digit;
628 if (digit >= 0 && digit <= 9) {
629 value = value * 10 + digit;
632 if (digit >= 0 && digit <= 9) {
633 value = value * 10 + digit;
636 if (digit >= 0 && digit <= 9) {
637 value = value * 10 + digit;
640 if (digit >= 0 && digit <= 9) {
641 value = value * 10 + digit;
643 /* Now got 9 digits, so need to check
644 each time for overflow. */
646 while (digit >= 0 && digit <= 9
647 && (value < max_div_10
648 || (value == max_div_10
649 && digit <= max_mod_10))) {
650 value = value * 10 + digit;
656 if (digit >= 0 && digit <= 9
659 skip the remaining digits, don't
660 worry about setting *valuep. */
663 } while (s < send && isDIGIT(*s));
665 IS_NUMBER_GREATER_THAN_UV_MAX;
685 numtype |= IS_NUMBER_IN_UV;
690 if (GROK_NUMERIC_RADIX(&s, send)) {
691 numtype |= IS_NUMBER_NOT_INT;
692 while (s < send && isDIGIT(*s)) /* optional digits after the radix */
696 else if (GROK_NUMERIC_RADIX(&s, send)) {
697 numtype |= IS_NUMBER_NOT_INT | IS_NUMBER_IN_UV; /* valuep assigned below */
698 /* no digits before the radix means we need digits after it */
699 if (s < send && isDIGIT(*s)) {
702 } while (s < send && isDIGIT(*s));
704 /* integer approximation is valid - it's 0. */
710 } else if (*s == 'I' || *s == 'i') {
711 s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
712 s++; if (s == send || (*s != 'F' && *s != 'f')) return 0;
713 s++; if (s < send && (*s == 'I' || *s == 'i')) {
714 s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
715 s++; if (s == send || (*s != 'I' && *s != 'i')) return 0;
716 s++; if (s == send || (*s != 'T' && *s != 't')) return 0;
717 s++; if (s == send || (*s != 'Y' && *s != 'y')) return 0;
721 } else if (*s == 'N' || *s == 'n') {
722 /* XXX TODO: There are signaling NaNs and quiet NaNs. */
723 s++; if (s == send || (*s != 'A' && *s != 'a')) return 0;
724 s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
731 numtype &= IS_NUMBER_NEG; /* Keep track of sign */
732 numtype |= IS_NUMBER_INFINITY | IS_NUMBER_NOT_INT;
734 numtype &= IS_NUMBER_NEG; /* Keep track of sign */
735 numtype |= IS_NUMBER_NAN | IS_NUMBER_NOT_INT;
736 } else if (s < send) {
737 /* we can have an optional exponent part */
738 if (*s == 'e' || *s == 'E') {
739 /* The only flag we keep is sign. Blow away any "it's UV" */
740 numtype &= IS_NUMBER_NEG;
741 numtype |= IS_NUMBER_NOT_INT;
743 if (s < send && (*s == '-' || *s == '+'))
745 if (s < send && isDIGIT(*s)) {
748 } while (s < send && isDIGIT(*s));
754 while (s < send && isSPACE(*s))
758 if (len == 10 && memEQ(pv, "0 but true", 10)) {
761 return IS_NUMBER_IN_UV;
767 S_mulexp10(NV value, I32 exponent)
779 /* On OpenVMS VAX we by default use the D_FLOAT double format,
780 * and that format does not have *easy* capabilities [1] for
781 * overflowing doubles 'silently' as IEEE fp does. We also need
782 * to support G_FLOAT on both VAX and Alpha, and though the exponent
783 * range is much larger than D_FLOAT it still doesn't do silent
784 * overflow. Therefore we need to detect early whether we would
785 * overflow (this is the behaviour of the native string-to-float
786 * conversion routines, and therefore of native applications, too).
788 * [1] Trying to establish a condition handler to trap floating point
789 * exceptions is not a good idea. */
791 /* In UNICOS and in certain Cray models (such as T90) there is no
792 * IEEE fp, and no way at all from C to catch fp overflows gracefully.
793 * There is something you can do if you are willing to use some
794 * inline assembler: the instruction is called DFI-- but that will
795 * disable *all* floating point interrupts, a little bit too large
796 * a hammer. Therefore we need to catch potential overflows before
799 #if ((defined(VMS) && !defined(_IEEE_FP)) || defined(_UNICOS)) && defined(NV_MAX_10_EXP)
801 const NV exp_v = log10(value);
802 if (exponent >= NV_MAX_10_EXP || exponent + exp_v >= NV_MAX_10_EXP)
805 if (-(exponent + exp_v) >= NV_MAX_10_EXP)
807 while (-exponent >= NV_MAX_10_EXP) {
808 /* combination does not overflow, but 10^(-exponent) does */
818 exponent = -exponent;
820 /* for something like 1234 x 10^-309, the action of calculating
821 * the intermediate value 10^309 then returning 1234 / (10^309)
822 * will fail, since 10^309 becomes infinity. In this case try to
823 * refactor it as 123 / (10^308) etc.
825 while (value && exponent > NV_MAX_10_EXP) {
831 for (bit = 1; exponent; bit <<= 1) {
832 if (exponent & bit) {
835 /* Floating point exceptions are supposed to be turned off,
836 * but if we're obviously done, don't risk another iteration.
838 if (exponent == 0) break;
842 return negative ? value / result : value * result;
846 Perl_my_atof(pTHX_ const char* s)
849 #ifdef USE_LOCALE_NUMERIC
850 PERL_ARGS_ASSERT_MY_ATOF;
853 DECLARE_STORE_LC_NUMERIC_SET_TO_NEEDED();
854 if (PL_numeric_radix_sv && IN_LC(LC_NUMERIC)) {
855 const char *standard = NULL, *local = NULL;
856 bool use_standard_radix;
858 /* Look through the string for the first thing that looks like a
859 * decimal point: either the value in the current locale or the
860 * standard fallback of '.'. The one which appears earliest in the
861 * input string is the one that we should have atof look for. Note
862 * that we have to determine this beforehand because on some
863 * systems, Perl_atof2 is just a wrapper around the system's atof.
865 standard = strchr(s, '.');
866 local = strstr(s, SvPV_nolen(PL_numeric_radix_sv));
868 use_standard_radix = standard && (!local || standard < local);
870 if (use_standard_radix)
871 SET_NUMERIC_STANDARD();
875 if (use_standard_radix)
880 RESTORE_LC_NUMERIC();
889 Perl_my_atof2(pTHX_ const char* orig, NV* value)
891 NV result[3] = {0.0, 0.0, 0.0};
892 const char* s = orig;
894 UV accumulator[2] = {0,0}; /* before/after dp */
896 const char* send = s + strlen(orig) - 1;
898 I32 exp_adjust[2] = {0,0};
899 I32 exp_acc[2] = {-1, -1};
900 /* the current exponent adjust for the accumulators */
905 I32 sig_digits = 0; /* noof significant digits seen so far */
907 PERL_ARGS_ASSERT_MY_ATOF2;
909 /* There is no point in processing more significant digits
910 * than the NV can hold. Note that NV_DIG is a lower-bound value,
911 * while we need an upper-bound value. We add 2 to account for this;
912 * since it will have been conservative on both the first and last digit.
913 * For example a 32-bit mantissa with an exponent of 4 would have
914 * exact values in the set
922 * where for the purposes of calculating NV_DIG we would have to discount
923 * both the first and last digit, since neither can hold all values from
924 * 0..9; but for calculating the value we must examine those two digits.
926 #ifdef MAX_SIG_DIG_PLUS
927 /* It is not necessarily the case that adding 2 to NV_DIG gets all the
928 possible digits in a NV, especially if NVs are not IEEE compliant
929 (e.g., long doubles on IRIX) - Allen <allens@cpan.org> */
930 # define MAX_SIG_DIGITS (NV_DIG+MAX_SIG_DIG_PLUS)
932 # define MAX_SIG_DIGITS (NV_DIG+2)
935 /* the max number we can accumulate in a UV, and still safely do 10*N+9 */
936 #define MAX_ACCUMULATE ( (UV) ((UV_MAX - 9)/10))
938 /* leading whitespace */
951 /* punt to strtod for NaN/Inf; if no support for it there, tough luck */
954 if (*s == 'n' || *s == 'N' || *s == 'i' || *s == 'I') {
955 const char *p = negative ? s - 1 : s;
958 rslt = strtod(p, &endp);
966 /* we accumulate digits into an integer; when this becomes too
967 * large, we add the total to NV and start again */
977 /* don't start counting until we see the first significant
978 * digit, eg the 5 in 0.00005... */
979 if (!sig_digits && digit == 0)
982 if (++sig_digits > MAX_SIG_DIGITS) {
983 /* limits of precision reached */
985 ++accumulator[seen_dp];
986 } else if (digit == 5) {
987 if (old_digit % 2) { /* round to even - Allen */
988 ++accumulator[seen_dp];
996 /* skip remaining digits */
997 while (isDIGIT(*s)) {
1003 /* warn of loss of precision? */
1006 if (accumulator[seen_dp] > MAX_ACCUMULATE) {
1007 /* add accumulator to result and start again */
1008 result[seen_dp] = S_mulexp10(result[seen_dp],
1010 + (NV)accumulator[seen_dp];
1011 accumulator[seen_dp] = 0;
1012 exp_acc[seen_dp] = 0;
1014 accumulator[seen_dp] = accumulator[seen_dp] * 10 + digit;
1018 else if (!seen_dp && GROK_NUMERIC_RADIX(&s, send)) {
1020 if (sig_digits > MAX_SIG_DIGITS) {
1023 } while (isDIGIT(*s));
1032 result[0] = S_mulexp10(result[0], exp_acc[0]) + (NV)accumulator[0];
1034 result[1] = S_mulexp10(result[1], exp_acc[1]) + (NV)accumulator[1];
1037 if (seen_digit && (*s == 'e' || *s == 'E')) {
1038 bool expnegative = 0;
1049 exponent = exponent * 10 + (*s++ - '0');
1051 exponent = -exponent;
1056 /* now apply the exponent */
1059 result[2] = S_mulexp10(result[0],exponent+exp_adjust[0])
1060 + S_mulexp10(result[1],exponent-exp_adjust[1]);
1062 result[2] = S_mulexp10(result[0],exponent+exp_adjust[0]);
1065 /* now apply the sign */
1067 result[2] = -result[2];
1068 #endif /* USE_PERL_ATOF */
1073 #if ! defined(HAS_MODFL) && defined(HAS_AINTL) && defined(HAS_COPYSIGNL)
1075 Perl_my_modfl(long double x, long double *ip)
1078 return (x == *ip ? copysignl(0.0L, x) : x - *ip);
1082 #if ! defined(HAS_FREXPL) && defined(HAS_ILOGBL) && defined(HAS_SCALBNL)
1084 Perl_my_frexpl(long double x, int *e) {
1085 *e = x == 0.0L ? 0 : ilogbl(x) + 1;
1086 return (scalbnl(x, -*e));
1091 =for apidoc Perl_signbit
1093 Return a non-zero integer if the sign bit on an NV is set, and 0 if
1096 If Configure detects this system has a signbit() that will work with
1097 our NVs, then we just use it via the #define in perl.h. Otherwise,
1098 fall back on this implementation. As a first pass, this gets everything
1099 right except -0.0. Alas, catching -0.0 is the main use for this function,
1100 so this is not too helpful yet. Still, at least we have the scaffolding
1101 in place to support other systems, should that prove useful.
1104 Configure notes: This function is called 'Perl_signbit' instead of a
1105 plain 'signbit' because it is easy to imagine a system having a signbit()
1106 function or macro that doesn't happen to work with our particular choice
1107 of NVs. We shouldn't just re-#define signbit as Perl_signbit and expect
1108 the standard system headers to be happy. Also, this is a no-context
1109 function (no pTHX_) because Perl_signbit() is usually re-#defined in
1110 perl.h as a simple macro call to the system's signbit().
1111 Users should just always call Perl_signbit().
1115 #if !defined(HAS_SIGNBIT)
1117 Perl_signbit(NV x) {
1118 return (x < 0.0) ? 1 : 0;
1124 * c-indentation-style: bsd
1126 * indent-tabs-mode: nil
1129 * ex: set ts=8 sts=4 sw=4 et: