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
33 Perl_cast_ulong(pTHX_ NV f)
37 return f < I32_MIN ? (U32) I32_MIN : (U32)(I32) f;
40 if (f < U32_MAX_P1_HALF)
43 return ((U32) f) | (1 + U32_MAX >> 1);
48 return f > 0 ? U32_MAX : 0 /* NaN */;
52 Perl_cast_i32(pTHX_ NV f)
56 return f < I32_MIN ? I32_MIN : (I32) f;
59 if (f < U32_MAX_P1_HALF)
62 return (I32)(((U32) f) | (1 + U32_MAX >> 1));
67 return f > 0 ? (I32)U32_MAX : 0 /* NaN */;
71 Perl_cast_iv(pTHX_ NV f)
75 return f < IV_MIN ? IV_MIN : (IV) f;
78 /* For future flexibility allowing for sizeof(UV) >= sizeof(IV) */
79 if (f < UV_MAX_P1_HALF)
82 return (IV)(((UV) f) | (1 + UV_MAX >> 1));
87 return f > 0 ? (IV)UV_MAX : 0 /* NaN */;
91 Perl_cast_uv(pTHX_ NV f)
95 return f < IV_MIN ? (UV) IV_MIN : (UV)(IV) f;
98 if (f < UV_MAX_P1_HALF)
101 return ((UV) f) | (1 + UV_MAX >> 1);
106 return f > 0 ? UV_MAX : 0 /* NaN */;
112 converts a string representing a binary number to numeric form.
114 On entry I<start> and I<*len> give the string to scan, I<*flags> gives
115 conversion flags, and I<result> should be NULL or a pointer to an NV.
116 The scan stops at the end of the string, or the first invalid character.
117 Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
118 invalid character will also trigger a warning.
119 On return I<*len> is set to the length of the scanned string,
120 and I<*flags> gives output flags.
122 If the value is <= C<UV_MAX> it is returned as a UV, the output flags are clear,
123 and nothing is written to I<*result>. If the value is > UV_MAX C<grok_bin>
124 returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
125 and writes the value to I<*result> (or the value is discarded if I<result>
128 The binary number may optionally be prefixed with "0b" or "b" unless
129 C<PERL_SCAN_DISALLOW_PREFIX> is set in I<*flags> on entry. If
130 C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the binary
131 number may use '_' characters to separate digits.
135 Not documented yet because experimental is C<PERL_SCAN_SILENT_NON_PORTABLE
136 which suppresses any message for non-portable numbers that are still valid
141 Perl_grok_bin(pTHX_ const char *start, STRLEN *len_p, I32 *flags, NV *result)
143 const char *s = start;
148 const UV max_div_2 = UV_MAX / 2;
149 const bool allow_underscores = cBOOL(*flags & PERL_SCAN_ALLOW_UNDERSCORES);
150 bool overflowed = FALSE;
153 PERL_ARGS_ASSERT_GROK_BIN;
155 if (!(*flags & PERL_SCAN_DISALLOW_PREFIX)) {
156 /* strip off leading b or 0b.
157 for compatibility silently suffer "b" and "0b" as valid binary
160 if (s[0] == 'b' || s[0] == 'B') {
164 else if (len >= 2 && s[0] == '0' && (s[1] == 'b' || s[1] == 'B')) {
171 for (; len-- && (bit = *s); s++) {
172 if (bit == '0' || bit == '1') {
173 /* Write it in this wonky order with a goto to attempt to get the
174 compiler to make the common case integer-only loop pretty tight.
175 With gcc seems to be much straighter code than old scan_bin. */
178 if (value <= max_div_2) {
179 value = (value << 1) | (bit - '0');
182 /* Bah. We're just overflowed. */
183 /* diag_listed_as: Integer overflow in %s number */
184 Perl_ck_warner_d(aTHX_ packWARN(WARN_OVERFLOW),
185 "Integer overflow in binary number");
187 value_nv = (NV) value;
190 /* If an NV has not enough bits in its mantissa to
191 * represent a UV this summing of small low-order numbers
192 * is a waste of time (because the NV cannot preserve
193 * the low-order bits anyway): we could just remember when
194 * did we overflow and in the end just multiply value_nv by the
196 value_nv += (NV)(bit - '0');
199 if (bit == '_' && len && allow_underscores && (bit = s[1])
200 && (bit == '0' || bit == '1'))
206 if (!(*flags & PERL_SCAN_SILENT_ILLDIGIT))
207 Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
208 "Illegal binary digit '%c' ignored", *s);
212 if ( ( overflowed && value_nv > 4294967295.0)
214 || (!overflowed && value > 0xffffffff
215 && ! (*flags & PERL_SCAN_SILENT_NON_PORTABLE))
218 Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE),
219 "Binary number > 0b11111111111111111111111111111111 non-portable");
226 *flags = PERL_SCAN_GREATER_THAN_UV_MAX;
235 converts a string representing a hex number to numeric form.
237 On entry I<start> and I<*len_p> give the string to scan, I<*flags> gives
238 conversion flags, and I<result> should be NULL or a pointer to an NV.
239 The scan stops at the end of the string, or the first invalid character.
240 Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
241 invalid character will also trigger a warning.
242 On return I<*len> is set to the length of the scanned string,
243 and I<*flags> gives output flags.
245 If the value is <= UV_MAX it is returned as a UV, the output flags are clear,
246 and nothing is written to I<*result>. If the value is > UV_MAX C<grok_hex>
247 returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
248 and writes the value to I<*result> (or the value is discarded if I<result>
251 The hex number may optionally be prefixed with "0x" or "x" unless
252 C<PERL_SCAN_DISALLOW_PREFIX> is set in I<*flags> on entry. If
253 C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the hex
254 number may use '_' characters to separate digits.
258 Not documented yet because experimental is C<PERL_SCAN_SILENT_NON_PORTABLE
259 which suppresses any message for non-portable numbers that are still valid
264 Perl_grok_hex(pTHX_ const char *start, STRLEN *len_p, I32 *flags, NV *result)
267 const char *s = start;
271 const UV max_div_16 = UV_MAX / 16;
272 const bool allow_underscores = cBOOL(*flags & PERL_SCAN_ALLOW_UNDERSCORES);
273 bool overflowed = FALSE;
275 PERL_ARGS_ASSERT_GROK_HEX;
277 if (!(*flags & PERL_SCAN_DISALLOW_PREFIX)) {
278 /* strip off leading x or 0x.
279 for compatibility silently suffer "x" and "0x" as valid hex numbers.
282 if (s[0] == 'x' || s[0] == 'X') {
286 else if (len >= 2 && s[0] == '0' && (s[1] == 'x' || s[1] == 'X')) {
293 for (; len-- && *s; s++) {
295 /* Write it in this wonky order with a goto to attempt to get the
296 compiler to make the common case integer-only loop pretty tight.
297 With gcc seems to be much straighter code than old scan_hex. */
300 if (value <= max_div_16) {
301 value = (value << 4) | XDIGIT_VALUE(*s);
304 /* Bah. We're just overflowed. */
305 /* diag_listed_as: Integer overflow in %s number */
306 Perl_ck_warner_d(aTHX_ packWARN(WARN_OVERFLOW),
307 "Integer overflow in hexadecimal number");
309 value_nv = (NV) value;
312 /* If an NV has not enough bits in its mantissa to
313 * represent a UV this summing of small low-order numbers
314 * is a waste of time (because the NV cannot preserve
315 * the low-order bits anyway): we could just remember when
316 * did we overflow and in the end just multiply value_nv by the
317 * right amount of 16-tuples. */
318 value_nv += (NV) XDIGIT_VALUE(*s);
321 if (*s == '_' && len && allow_underscores && s[1]
328 if (!(*flags & PERL_SCAN_SILENT_ILLDIGIT))
329 Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
330 "Illegal hexadecimal digit '%c' ignored", *s);
334 if ( ( overflowed && value_nv > 4294967295.0)
336 || (!overflowed && value > 0xffffffff
337 && ! (*flags & PERL_SCAN_SILENT_NON_PORTABLE))
340 Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE),
341 "Hexadecimal number > 0xffffffff non-portable");
348 *flags = PERL_SCAN_GREATER_THAN_UV_MAX;
357 converts a string representing an octal number to numeric form.
359 On entry I<start> and I<*len> give the string to scan, I<*flags> gives
360 conversion flags, and I<result> should be NULL or a pointer to an NV.
361 The scan stops at the end of the string, or the first invalid character.
362 Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
363 8 or 9 will also trigger a warning.
364 On return I<*len> is set to the length of the scanned string,
365 and I<*flags> gives output flags.
367 If the value is <= UV_MAX it is returned as a UV, the output flags are clear,
368 and nothing is written to I<*result>. If the value is > UV_MAX C<grok_oct>
369 returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
370 and writes the value to I<*result> (or the value is discarded if I<result>
373 If C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the octal
374 number may use '_' characters to separate digits.
378 Not documented yet because experimental is C<PERL_SCAN_SILENT_NON_PORTABLE>
379 which suppresses any message for non-portable numbers, but which are valid
384 Perl_grok_oct(pTHX_ const char *start, STRLEN *len_p, I32 *flags, NV *result)
386 const char *s = start;
390 const UV max_div_8 = UV_MAX / 8;
391 const bool allow_underscores = cBOOL(*flags & PERL_SCAN_ALLOW_UNDERSCORES);
392 bool overflowed = FALSE;
394 PERL_ARGS_ASSERT_GROK_OCT;
396 for (; len-- && *s; s++) {
398 /* Write it in this wonky order with a goto to attempt to get the
399 compiler to make the common case integer-only loop pretty tight.
403 if (value <= max_div_8) {
404 value = (value << 3) | OCTAL_VALUE(*s);
407 /* Bah. We're just overflowed. */
408 /* diag_listed_as: Integer overflow in %s number */
409 Perl_ck_warner_d(aTHX_ packWARN(WARN_OVERFLOW),
410 "Integer overflow in octal number");
412 value_nv = (NV) value;
415 /* If an NV has not enough bits in its mantissa to
416 * represent a UV this summing of small low-order numbers
417 * is a waste of time (because the NV cannot preserve
418 * the low-order bits anyway): we could just remember when
419 * did we overflow and in the end just multiply value_nv by the
420 * right amount of 8-tuples. */
421 value_nv += (NV) OCTAL_VALUE(*s);
424 if (*s == '_' && len && allow_underscores && isOCTAL(s[1])) {
429 /* Allow \octal to work the DWIM way (that is, stop scanning
430 * as soon as non-octal characters are seen, complain only if
431 * someone seems to want to use the digits eight and nine. Since we
432 * know it is not octal, then if isDIGIT, must be an 8 or 9). */
434 if (!(*flags & PERL_SCAN_SILENT_ILLDIGIT))
435 Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
436 "Illegal octal digit '%c' ignored", *s);
441 if ( ( overflowed && value_nv > 4294967295.0)
443 || (!overflowed && value > 0xffffffff
444 && ! (*flags & PERL_SCAN_SILENT_NON_PORTABLE))
447 Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE),
448 "Octal number > 037777777777 non-portable");
455 *flags = PERL_SCAN_GREATER_THAN_UV_MAX;
464 For backwards compatibility. Use C<grok_bin> instead.
468 For backwards compatibility. Use C<grok_hex> instead.
472 For backwards compatibility. Use C<grok_oct> instead.
478 Perl_scan_bin(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
481 I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
482 const UV ruv = grok_bin (start, &len, &flags, &rnv);
484 PERL_ARGS_ASSERT_SCAN_BIN;
487 return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
491 Perl_scan_oct(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
494 I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
495 const UV ruv = grok_oct (start, &len, &flags, &rnv);
497 PERL_ARGS_ASSERT_SCAN_OCT;
500 return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
504 Perl_scan_hex(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
507 I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
508 const UV ruv = grok_hex (start, &len, &flags, &rnv);
510 PERL_ARGS_ASSERT_SCAN_HEX;
513 return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
517 =for apidoc grok_numeric_radix
519 Scan and skip for a numeric decimal separator (radix).
524 Perl_grok_numeric_radix(pTHX_ const char **sp, const char *send)
526 #ifdef USE_LOCALE_NUMERIC
529 PERL_ARGS_ASSERT_GROK_NUMERIC_RADIX;
531 if (IN_LC(LC_NUMERIC)) {
532 DECLARE_STORE_LC_NUMERIC_SET_TO_NEEDED();
533 if (PL_numeric_radix_sv) {
535 const char * const radix = SvPV(PL_numeric_radix_sv, len);
536 if (*sp + len <= send && memEQ(*sp, radix, len)) {
538 RESTORE_LC_NUMERIC();
542 RESTORE_LC_NUMERIC();
544 /* always try "." if numeric radix didn't match because
545 * we may have data from different locales mixed */
548 PERL_ARGS_ASSERT_GROK_NUMERIC_RADIX;
550 if (*sp < send && **sp == '.') {
558 =for apidoc grok_number
560 Recognise (or not) a number. The type of the number is returned
561 (0 if unrecognised), otherwise it is a bit-ORed combination of
562 IS_NUMBER_IN_UV, IS_NUMBER_GREATER_THAN_UV_MAX, IS_NUMBER_NOT_INT,
563 IS_NUMBER_NEG, IS_NUMBER_INFINITY, IS_NUMBER_NAN (defined in perl.h).
565 If the value of the number can fit in a UV, it is returned in the *valuep
566 IS_NUMBER_IN_UV will be set to indicate that *valuep is valid, IS_NUMBER_IN_UV
567 will never be set unless *valuep is valid, but *valuep may have been assigned
568 to during processing even though IS_NUMBER_IN_UV is not set on return.
569 If valuep is NULL, IS_NUMBER_IN_UV will be set for the same cases as when
570 valuep is non-NULL, but no actual assignment (or SEGV) will occur.
572 IS_NUMBER_NOT_INT will be set with IS_NUMBER_IN_UV if trailing decimals were
573 seen (in which case *valuep gives the true value truncated to an integer), and
574 IS_NUMBER_NEG if the number is negative (in which case *valuep holds the
575 absolute value). IS_NUMBER_IN_UV is not set if e notation was used or the
576 number is larger than a UV.
581 Perl_grok_number(pTHX_ const char *pv, STRLEN len, UV *valuep)
584 const char * const send = pv + len;
585 const UV max_div_10 = UV_MAX / 10;
586 const char max_mod_10 = UV_MAX % 10;
591 PERL_ARGS_ASSERT_GROK_NUMBER;
593 while (s < send && isSPACE(*s))
597 } else if (*s == '-') {
599 numtype = IS_NUMBER_NEG;
607 /* next must be digit or the radix separator or beginning of infinity */
609 /* UVs are at least 32 bits, so the first 9 decimal digits cannot
612 /* This construction seems to be more optimiser friendly.
613 (without it gcc does the isDIGIT test and the *s - '0' separately)
614 With it gcc on arm is managing 6 instructions (6 cycles) per digit.
615 In theory the optimiser could deduce how far to unroll the loop
616 before checking for overflow. */
618 int digit = *s - '0';
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;
647 if (digit >= 0 && digit <= 9) {
648 value = value * 10 + digit;
650 /* Now got 9 digits, so need to check
651 each time for overflow. */
653 while (digit >= 0 && digit <= 9
654 && (value < max_div_10
655 || (value == max_div_10
656 && digit <= max_mod_10))) {
657 value = value * 10 + digit;
663 if (digit >= 0 && digit <= 9
666 skip the remaining digits, don't
667 worry about setting *valuep. */
670 } while (s < send && isDIGIT(*s));
672 IS_NUMBER_GREATER_THAN_UV_MAX;
692 numtype |= IS_NUMBER_IN_UV;
697 if (GROK_NUMERIC_RADIX(&s, send)) {
698 numtype |= IS_NUMBER_NOT_INT;
699 while (s < send && isDIGIT(*s)) /* optional digits after the radix */
703 else if (GROK_NUMERIC_RADIX(&s, send)) {
704 numtype |= IS_NUMBER_NOT_INT | IS_NUMBER_IN_UV; /* valuep assigned below */
705 /* no digits before the radix means we need digits after it */
706 if (s < send && isDIGIT(*s)) {
709 } while (s < send && isDIGIT(*s));
711 /* integer approximation is valid - it's 0. */
717 } else if (*s == 'I' || *s == 'i') {
718 s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
719 s++; if (s == send || (*s != 'F' && *s != 'f')) return 0;
720 s++; if (s < send && (*s == 'I' || *s == 'i')) {
721 s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
722 s++; if (s == send || (*s != 'I' && *s != 'i')) return 0;
723 s++; if (s == send || (*s != 'T' && *s != 't')) return 0;
724 s++; if (s == send || (*s != 'Y' && *s != 'y')) return 0;
728 } else if (*s == 'N' || *s == 'n') {
729 /* XXX TODO: There are signaling NaNs and quiet NaNs. */
730 s++; if (s == send || (*s != 'A' && *s != 'a')) return 0;
731 s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
738 numtype &= IS_NUMBER_NEG; /* Keep track of sign */
739 numtype |= IS_NUMBER_INFINITY | IS_NUMBER_NOT_INT;
741 numtype &= IS_NUMBER_NEG; /* Keep track of sign */
742 numtype |= IS_NUMBER_NAN | IS_NUMBER_NOT_INT;
743 } else if (s < send) {
744 /* we can have an optional exponent part */
745 if (*s == 'e' || *s == 'E') {
746 /* The only flag we keep is sign. Blow away any "it's UV" */
747 numtype &= IS_NUMBER_NEG;
748 numtype |= IS_NUMBER_NOT_INT;
750 if (s < send && (*s == '-' || *s == '+'))
752 if (s < send && isDIGIT(*s)) {
755 } while (s < send && isDIGIT(*s));
761 while (s < send && isSPACE(*s))
765 if (len == 10 && memEQ(pv, "0 but true", 10)) {
768 return IS_NUMBER_IN_UV;
774 S_mulexp10(NV value, I32 exponent)
786 /* On OpenVMS VAX we by default use the D_FLOAT double format,
787 * and that format does not have *easy* capabilities [1] for
788 * overflowing doubles 'silently' as IEEE fp does. We also need
789 * to support G_FLOAT on both VAX and Alpha, and though the exponent
790 * range is much larger than D_FLOAT it still doesn't do silent
791 * overflow. Therefore we need to detect early whether we would
792 * overflow (this is the behaviour of the native string-to-float
793 * conversion routines, and therefore of native applications, too).
795 * [1] Trying to establish a condition handler to trap floating point
796 * exceptions is not a good idea. */
798 /* In UNICOS and in certain Cray models (such as T90) there is no
799 * IEEE fp, and no way at all from C to catch fp overflows gracefully.
800 * There is something you can do if you are willing to use some
801 * inline assembler: the instruction is called DFI-- but that will
802 * disable *all* floating point interrupts, a little bit too large
803 * a hammer. Therefore we need to catch potential overflows before
806 #if ((defined(VMS) && !defined(_IEEE_FP)) || defined(_UNICOS)) && defined(NV_MAX_10_EXP)
808 const NV exp_v = log10(value);
809 if (exponent >= NV_MAX_10_EXP || exponent + exp_v >= NV_MAX_10_EXP)
812 if (-(exponent + exp_v) >= NV_MAX_10_EXP)
814 while (-exponent >= NV_MAX_10_EXP) {
815 /* combination does not overflow, but 10^(-exponent) does */
825 exponent = -exponent;
827 /* for something like 1234 x 10^-309, the action of calculating
828 * the intermediate value 10^309 then returning 1234 / (10^309)
829 * will fail, since 10^309 becomes infinity. In this case try to
830 * refactor it as 123 / (10^308) etc.
832 while (value && exponent > NV_MAX_10_EXP) {
838 for (bit = 1; exponent; bit <<= 1) {
839 if (exponent & bit) {
842 /* Floating point exceptions are supposed to be turned off,
843 * but if we're obviously done, don't risk another iteration.
845 if (exponent == 0) break;
849 return negative ? value / result : value * result;
853 Perl_my_atof(pTHX_ const char* s)
856 #ifdef USE_LOCALE_NUMERIC
859 PERL_ARGS_ASSERT_MY_ATOF;
862 DECLARE_STORE_LC_NUMERIC_SET_TO_NEEDED();
863 if (PL_numeric_radix_sv && IN_LC(LC_NUMERIC)) {
864 const char *standard = NULL, *local = NULL;
865 bool use_standard_radix;
867 /* Look through the string for the first thing that looks like a
868 * decimal point: either the value in the current locale or the
869 * standard fallback of '.'. The one which appears earliest in the
870 * input string is the one that we should have atof look for. Note
871 * that we have to determine this beforehand because on some
872 * systems, Perl_atof2 is just a wrapper around the system's atof.
874 standard = strchr(s, '.');
875 local = strstr(s, SvPV_nolen(PL_numeric_radix_sv));
877 use_standard_radix = standard && (!local || standard < local);
879 if (use_standard_radix)
880 SET_NUMERIC_STANDARD();
884 if (use_standard_radix)
889 RESTORE_LC_NUMERIC();
898 Perl_my_atof2(pTHX_ const char* orig, NV* value)
900 NV result[3] = {0.0, 0.0, 0.0};
901 const char* s = orig;
903 UV accumulator[2] = {0,0}; /* before/after dp */
905 const char* send = s + strlen(orig) - 1;
907 I32 exp_adjust[2] = {0,0};
908 I32 exp_acc[2] = {-1, -1};
909 /* the current exponent adjust for the accumulators */
914 I32 sig_digits = 0; /* noof significant digits seen so far */
916 PERL_ARGS_ASSERT_MY_ATOF2;
918 /* There is no point in processing more significant digits
919 * than the NV can hold. Note that NV_DIG is a lower-bound value,
920 * while we need an upper-bound value. We add 2 to account for this;
921 * since it will have been conservative on both the first and last digit.
922 * For example a 32-bit mantissa with an exponent of 4 would have
923 * exact values in the set
931 * where for the purposes of calculating NV_DIG we would have to discount
932 * both the first and last digit, since neither can hold all values from
933 * 0..9; but for calculating the value we must examine those two digits.
935 #ifdef MAX_SIG_DIG_PLUS
936 /* It is not necessarily the case that adding 2 to NV_DIG gets all the
937 possible digits in a NV, especially if NVs are not IEEE compliant
938 (e.g., long doubles on IRIX) - Allen <allens@cpan.org> */
939 # define MAX_SIG_DIGITS (NV_DIG+MAX_SIG_DIG_PLUS)
941 # define MAX_SIG_DIGITS (NV_DIG+2)
944 /* the max number we can accumulate in a UV, and still safely do 10*N+9 */
945 #define MAX_ACCUMULATE ( (UV) ((UV_MAX - 9)/10))
947 /* leading whitespace */
960 /* punt to strtod for NaN/Inf; if no support for it there, tough luck */
963 if (*s == 'n' || *s == 'N' || *s == 'i' || *s == 'I') {
964 const char *p = negative ? s - 1 : s;
967 rslt = strtod(p, &endp);
975 /* we accumulate digits into an integer; when this becomes too
976 * large, we add the total to NV and start again */
986 /* don't start counting until we see the first significant
987 * digit, eg the 5 in 0.00005... */
988 if (!sig_digits && digit == 0)
991 if (++sig_digits > MAX_SIG_DIGITS) {
992 /* limits of precision reached */
994 ++accumulator[seen_dp];
995 } else if (digit == 5) {
996 if (old_digit % 2) { /* round to even - Allen */
997 ++accumulator[seen_dp];
1005 /* skip remaining digits */
1006 while (isDIGIT(*s)) {
1012 /* warn of loss of precision? */
1015 if (accumulator[seen_dp] > MAX_ACCUMULATE) {
1016 /* add accumulator to result and start again */
1017 result[seen_dp] = S_mulexp10(result[seen_dp],
1019 + (NV)accumulator[seen_dp];
1020 accumulator[seen_dp] = 0;
1021 exp_acc[seen_dp] = 0;
1023 accumulator[seen_dp] = accumulator[seen_dp] * 10 + digit;
1027 else if (!seen_dp && GROK_NUMERIC_RADIX(&s, send)) {
1029 if (sig_digits > MAX_SIG_DIGITS) {
1032 } while (isDIGIT(*s));
1041 result[0] = S_mulexp10(result[0], exp_acc[0]) + (NV)accumulator[0];
1043 result[1] = S_mulexp10(result[1], exp_acc[1]) + (NV)accumulator[1];
1046 if (seen_digit && (*s == 'e' || *s == 'E')) {
1047 bool expnegative = 0;
1058 exponent = exponent * 10 + (*s++ - '0');
1060 exponent = -exponent;
1065 /* now apply the exponent */
1068 result[2] = S_mulexp10(result[0],exponent+exp_adjust[0])
1069 + S_mulexp10(result[1],exponent-exp_adjust[1]);
1071 result[2] = S_mulexp10(result[0],exponent+exp_adjust[0]);
1074 /* now apply the sign */
1076 result[2] = -result[2];
1077 #endif /* USE_PERL_ATOF */
1082 #if ! defined(HAS_MODFL) && defined(HAS_AINTL) && defined(HAS_COPYSIGNL)
1084 Perl_my_modfl(long double x, long double *ip)
1087 return (x == *ip ? copysignl(0.0L, x) : x - *ip);
1091 #if ! defined(HAS_FREXPL) && defined(HAS_ILOGBL) && defined(HAS_SCALBNL)
1093 Perl_my_frexpl(long double x, int *e) {
1094 *e = x == 0.0L ? 0 : ilogbl(x) + 1;
1095 return (scalbnl(x, -*e));
1100 =for apidoc Perl_signbit
1102 Return a non-zero integer if the sign bit on an NV is set, and 0 if
1105 If Configure detects this system has a signbit() that will work with
1106 our NVs, then we just use it via the #define in perl.h. Otherwise,
1107 fall back on this implementation. As a first pass, this gets everything
1108 right except -0.0. Alas, catching -0.0 is the main use for this function,
1109 so this is not too helpful yet. Still, at least we have the scaffolding
1110 in place to support other systems, should that prove useful.
1113 Configure notes: This function is called 'Perl_signbit' instead of a
1114 plain 'signbit' because it is easy to imagine a system having a signbit()
1115 function or macro that doesn't happen to work with our particular choice
1116 of NVs. We shouldn't just re-#define signbit as Perl_signbit and expect
1117 the standard system headers to be happy. Also, this is a no-context
1118 function (no pTHX_) because Perl_signbit() is usually re-#defined in
1119 perl.h as a simple macro call to the system's signbit().
1120 Users should just always call Perl_signbit().
1124 #if !defined(HAS_SIGNBIT)
1126 Perl_signbit(NV x) {
1127 return (x < 0.0) ? 1 : 0;
1133 * c-indentation-style: bsd
1135 * indent-tabs-mode: nil
1138 * ex: set ts=8 sts=4 sw=4 et: