forked from castaway/perl
/
numeric.c
1094 lines (978 loc) · 32.1 KB
/
numeric.c
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/* numeric.c
*
* Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
* 2002, 2003, 2004, 2005, 2006, 2007, 2008 by Larry Wall and others
*
* You may distribute under the terms of either the GNU General Public
* License or the Artistic License, as specified in the README file.
*
*/
/*
* "That only makes eleven (plus one mislaid) and not fourteen,
* unless wizards count differently to other people." --Beorn
*
* [p.115 of _The Hobbit_: "Queer Lodgings"]
*/
/*
=head1 Numeric functions
This file contains all the stuff needed by perl for manipulating numeric
values, including such things as replacements for the OS's atof() function
=cut
*/
#include "EXTERN.h"
#define PERL_IN_NUMERIC_C
#include "perl.h"
U32
Perl_cast_ulong(pTHX_ NV f)
{
PERL_UNUSED_CONTEXT;
if (f < 0.0)
return f < I32_MIN ? (U32) I32_MIN : (U32)(I32) f;
if (f < U32_MAX_P1) {
#if CASTFLAGS & 2
if (f < U32_MAX_P1_HALF)
return (U32) f;
f -= U32_MAX_P1_HALF;
return ((U32) f) | (1 + U32_MAX >> 1);
#else
return (U32) f;
#endif
}
return f > 0 ? U32_MAX : 0 /* NaN */;
}
I32
Perl_cast_i32(pTHX_ NV f)
{
PERL_UNUSED_CONTEXT;
if (f < I32_MAX_P1)
return f < I32_MIN ? I32_MIN : (I32) f;
if (f < U32_MAX_P1) {
#if CASTFLAGS & 2
if (f < U32_MAX_P1_HALF)
return (I32)(U32) f;
f -= U32_MAX_P1_HALF;
return (I32)(((U32) f) | (1 + U32_MAX >> 1));
#else
return (I32)(U32) f;
#endif
}
return f > 0 ? (I32)U32_MAX : 0 /* NaN */;
}
IV
Perl_cast_iv(pTHX_ NV f)
{
PERL_UNUSED_CONTEXT;
if (f < IV_MAX_P1)
return f < IV_MIN ? IV_MIN : (IV) f;
if (f < UV_MAX_P1) {
#if CASTFLAGS & 2
/* For future flexibility allowing for sizeof(UV) >= sizeof(IV) */
if (f < UV_MAX_P1_HALF)
return (IV)(UV) f;
f -= UV_MAX_P1_HALF;
return (IV)(((UV) f) | (1 + UV_MAX >> 1));
#else
return (IV)(UV) f;
#endif
}
return f > 0 ? (IV)UV_MAX : 0 /* NaN */;
}
UV
Perl_cast_uv(pTHX_ NV f)
{
PERL_UNUSED_CONTEXT;
if (f < 0.0)
return f < IV_MIN ? (UV) IV_MIN : (UV)(IV) f;
if (f < UV_MAX_P1) {
#if CASTFLAGS & 2
if (f < UV_MAX_P1_HALF)
return (UV) f;
f -= UV_MAX_P1_HALF;
return ((UV) f) | (1 + UV_MAX >> 1);
#else
return (UV) f;
#endif
}
return f > 0 ? UV_MAX : 0 /* NaN */;
}
/*
=for apidoc grok_bin
converts a string representing a binary number to numeric form.
On entry I<start> and I<*len> give the string to scan, I<*flags> gives
conversion flags, and I<result> should be NULL or a pointer to an NV.
The scan stops at the end of the string, or the first invalid character.
Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
invalid character will also trigger a warning.
On return I<*len> is set to the length of the scanned string,
and I<*flags> gives output flags.
If the value is <= C<UV_MAX> it is returned as a UV, the output flags are clear,
and nothing is written to I<*result>. If the value is > UV_MAX C<grok_bin>
returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
and writes the value to I<*result> (or the value is discarded if I<result>
is NULL).
The binary number may optionally be prefixed with "0b" or "b" unless
C<PERL_SCAN_DISALLOW_PREFIX> is set in I<*flags> on entry. If
C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the binary
number may use '_' characters to separate digits.
=cut
*/
UV
Perl_grok_bin(pTHX_ const char *start, STRLEN *len_p, I32 *flags, NV *result)
{
const char *s = start;
STRLEN len = *len_p;
UV value = 0;
NV value_nv = 0;
const UV max_div_2 = UV_MAX / 2;
const bool allow_underscores = cBOOL(*flags & PERL_SCAN_ALLOW_UNDERSCORES);
bool overflowed = FALSE;
char bit;
PERL_ARGS_ASSERT_GROK_BIN;
if (!(*flags & PERL_SCAN_DISALLOW_PREFIX)) {
/* strip off leading b or 0b.
for compatibility silently suffer "b" and "0b" as valid binary
numbers. */
if (len >= 1) {
if (s[0] == 'b' || s[0] == 'B') {
s++;
len--;
}
else if (len >= 2 && s[0] == '0' && (s[1] == 'b' || s[1] == 'B')) {
s+=2;
len-=2;
}
}
}
for (; len-- && (bit = *s); s++) {
if (bit == '0' || bit == '1') {
/* Write it in this wonky order with a goto to attempt to get the
compiler to make the common case integer-only loop pretty tight.
With gcc seems to be much straighter code than old scan_bin. */
redo:
if (!overflowed) {
if (value <= max_div_2) {
value = (value << 1) | (bit - '0');
continue;
}
/* Bah. We're just overflowed. */
Perl_ck_warner_d(aTHX_ packWARN(WARN_OVERFLOW),
"Integer overflow in binary number");
overflowed = TRUE;
value_nv = (NV) value;
}
value_nv *= 2.0;
/* If an NV has not enough bits in its mantissa to
* represent a UV this summing of small low-order numbers
* is a waste of time (because the NV cannot preserve
* the low-order bits anyway): we could just remember when
* did we overflow and in the end just multiply value_nv by the
* right amount. */
value_nv += (NV)(bit - '0');
continue;
}
if (bit == '_' && len && allow_underscores && (bit = s[1])
&& (bit == '0' || bit == '1'))
{
--len;
++s;
goto redo;
}
if (!(*flags & PERL_SCAN_SILENT_ILLDIGIT))
Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
"Illegal binary digit '%c' ignored", *s);
break;
}
if ( ( overflowed && value_nv > 4294967295.0)
#if UVSIZE > 4
|| (!overflowed && value > 0xffffffff )
#endif
) {
Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE),
"Binary number > 0b11111111111111111111111111111111 non-portable");
}
*len_p = s - start;
if (!overflowed) {
*flags = 0;
return value;
}
*flags = PERL_SCAN_GREATER_THAN_UV_MAX;
if (result)
*result = value_nv;
return UV_MAX;
}
/*
=for apidoc grok_hex
converts a string representing a hex number to numeric form.
On entry I<start> and I<*len> give the string to scan, I<*flags> gives
conversion flags, and I<result> should be NULL or a pointer to an NV.
The scan stops at the end of the string, or the first invalid character.
Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
invalid character will also trigger a warning.
On return I<*len> is set to the length of the scanned string,
and I<*flags> gives output flags.
If the value is <= UV_MAX it is returned as a UV, the output flags are clear,
and nothing is written to I<*result>. If the value is > UV_MAX C<grok_hex>
returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
and writes the value to I<*result> (or the value is discarded if I<result>
is NULL).
The hex number may optionally be prefixed with "0x" or "x" unless
C<PERL_SCAN_DISALLOW_PREFIX> is set in I<*flags> on entry. If
C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the hex
number may use '_' characters to separate digits.
=cut
*/
UV
Perl_grok_hex(pTHX_ const char *start, STRLEN *len_p, I32 *flags, NV *result)
{
dVAR;
const char *s = start;
STRLEN len = *len_p;
UV value = 0;
NV value_nv = 0;
const UV max_div_16 = UV_MAX / 16;
const bool allow_underscores = cBOOL(*flags & PERL_SCAN_ALLOW_UNDERSCORES);
bool overflowed = FALSE;
PERL_ARGS_ASSERT_GROK_HEX;
if (!(*flags & PERL_SCAN_DISALLOW_PREFIX)) {
/* strip off leading x or 0x.
for compatibility silently suffer "x" and "0x" as valid hex numbers.
*/
if (len >= 1) {
if (s[0] == 'x' || s[0] == 'X') {
s++;
len--;
}
else if (len >= 2 && s[0] == '0' && (s[1] == 'x' || s[1] == 'X')) {
s+=2;
len-=2;
}
}
}
for (; len-- && *s; s++) {
const char *hexdigit = strchr(PL_hexdigit, *s);
if (hexdigit) {
/* Write it in this wonky order with a goto to attempt to get the
compiler to make the common case integer-only loop pretty tight.
With gcc seems to be much straighter code than old scan_hex. */
redo:
if (!overflowed) {
if (value <= max_div_16) {
value = (value << 4) | ((hexdigit - PL_hexdigit) & 15);
continue;
}
/* Bah. We're just overflowed. */
Perl_ck_warner_d(aTHX_ packWARN(WARN_OVERFLOW),
"Integer overflow in hexadecimal number");
overflowed = TRUE;
value_nv = (NV) value;
}
value_nv *= 16.0;
/* If an NV has not enough bits in its mantissa to
* represent a UV this summing of small low-order numbers
* is a waste of time (because the NV cannot preserve
* the low-order bits anyway): we could just remember when
* did we overflow and in the end just multiply value_nv by the
* right amount of 16-tuples. */
value_nv += (NV)((hexdigit - PL_hexdigit) & 15);
continue;
}
if (*s == '_' && len && allow_underscores && s[1]
&& (hexdigit = strchr(PL_hexdigit, s[1])))
{
--len;
++s;
goto redo;
}
if (!(*flags & PERL_SCAN_SILENT_ILLDIGIT))
Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
"Illegal hexadecimal digit '%c' ignored", *s);
break;
}
if ( ( overflowed && value_nv > 4294967295.0)
#if UVSIZE > 4
|| (!overflowed && value > 0xffffffff )
#endif
) {
Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE),
"Hexadecimal number > 0xffffffff non-portable");
}
*len_p = s - start;
if (!overflowed) {
*flags = 0;
return value;
}
*flags = PERL_SCAN_GREATER_THAN_UV_MAX;
if (result)
*result = value_nv;
return UV_MAX;
}
/*
=for apidoc grok_oct
converts a string representing an octal number to numeric form.
On entry I<start> and I<*len> give the string to scan, I<*flags> gives
conversion flags, and I<result> should be NULL or a pointer to an NV.
The scan stops at the end of the string, or the first invalid character.
Unless C<PERL_SCAN_SILENT_ILLDIGIT> is set in I<*flags>, encountering an
8 or 9 will also trigger a warning.
On return I<*len> is set to the length of the scanned string,
and I<*flags> gives output flags.
If the value is <= UV_MAX it is returned as a UV, the output flags are clear,
and nothing is written to I<*result>. If the value is > UV_MAX C<grok_oct>
returns UV_MAX, sets C<PERL_SCAN_GREATER_THAN_UV_MAX> in the output flags,
and writes the value to I<*result> (or the value is discarded if I<result>
is NULL).
If C<PERL_SCAN_ALLOW_UNDERSCORES> is set in I<*flags> then the octal
number may use '_' characters to separate digits.
=cut
*/
UV
Perl_grok_oct(pTHX_ const char *start, STRLEN *len_p, I32 *flags, NV *result)
{
const char *s = start;
STRLEN len = *len_p;
UV value = 0;
NV value_nv = 0;
const UV max_div_8 = UV_MAX / 8;
const bool allow_underscores = cBOOL(*flags & PERL_SCAN_ALLOW_UNDERSCORES);
bool overflowed = FALSE;
PERL_ARGS_ASSERT_GROK_OCT;
for (; len-- && *s; s++) {
/* gcc 2.95 optimiser not smart enough to figure that this subtraction
out front allows slicker code. */
int digit = *s - '0';
if (digit >= 0 && digit <= 7) {
/* Write it in this wonky order with a goto to attempt to get the
compiler to make the common case integer-only loop pretty tight.
*/
redo:
if (!overflowed) {
if (value <= max_div_8) {
value = (value << 3) | digit;
continue;
}
/* Bah. We're just overflowed. */
Perl_ck_warner_d(aTHX_ packWARN(WARN_OVERFLOW),
"Integer overflow in octal number");
overflowed = TRUE;
value_nv = (NV) value;
}
value_nv *= 8.0;
/* If an NV has not enough bits in its mantissa to
* represent a UV this summing of small low-order numbers
* is a waste of time (because the NV cannot preserve
* the low-order bits anyway): we could just remember when
* did we overflow and in the end just multiply value_nv by the
* right amount of 8-tuples. */
value_nv += (NV)digit;
continue;
}
if (digit == ('_' - '0') && len && allow_underscores
&& (digit = s[1] - '0') && (digit >= 0 && digit <= 7))
{
--len;
++s;
goto redo;
}
/* Allow \octal to work the DWIM way (that is, stop scanning
* as soon as non-octal characters are seen, complain only if
* someone seems to want to use the digits eight and nine). */
if (digit == 8 || digit == 9) {
if (!(*flags & PERL_SCAN_SILENT_ILLDIGIT))
Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
"Illegal octal digit '%c' ignored", *s);
}
break;
}
if ( ( overflowed && value_nv > 4294967295.0)
#if UVSIZE > 4
|| (!overflowed && value > 0xffffffff )
#endif
) {
Perl_ck_warner(aTHX_ packWARN(WARN_PORTABLE),
"Octal number > 037777777777 non-portable");
}
*len_p = s - start;
if (!overflowed) {
*flags = 0;
return value;
}
*flags = PERL_SCAN_GREATER_THAN_UV_MAX;
if (result)
*result = value_nv;
return UV_MAX;
}
/*
=for apidoc scan_bin
For backwards compatibility. Use C<grok_bin> instead.
=for apidoc scan_hex
For backwards compatibility. Use C<grok_hex> instead.
=for apidoc scan_oct
For backwards compatibility. Use C<grok_oct> instead.
=cut
*/
NV
Perl_scan_bin(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
{
NV rnv;
I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
const UV ruv = grok_bin (start, &len, &flags, &rnv);
PERL_ARGS_ASSERT_SCAN_BIN;
*retlen = len;
return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
}
NV
Perl_scan_oct(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
{
NV rnv;
I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
const UV ruv = grok_oct (start, &len, &flags, &rnv);
PERL_ARGS_ASSERT_SCAN_OCT;
*retlen = len;
return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
}
NV
Perl_scan_hex(pTHX_ const char *start, STRLEN len, STRLEN *retlen)
{
NV rnv;
I32 flags = *retlen ? PERL_SCAN_ALLOW_UNDERSCORES : 0;
const UV ruv = grok_hex (start, &len, &flags, &rnv);
PERL_ARGS_ASSERT_SCAN_HEX;
*retlen = len;
return (flags & PERL_SCAN_GREATER_THAN_UV_MAX) ? rnv : (NV)ruv;
}
/*
=for apidoc grok_numeric_radix
Scan and skip for a numeric decimal separator (radix).
=cut
*/
bool
Perl_grok_numeric_radix(pTHX_ const char **sp, const char *send)
{
#ifdef USE_LOCALE_NUMERIC
dVAR;
PERL_ARGS_ASSERT_GROK_NUMERIC_RADIX;
if (PL_numeric_radix_sv && IN_LOCALE) {
STRLEN len;
const char * const radix = SvPV(PL_numeric_radix_sv, len);
if (*sp + len <= send && memEQ(*sp, radix, len)) {
*sp += len;
return TRUE;
}
}
/* always try "." if numeric radix didn't match because
* we may have data from different locales mixed */
#endif
PERL_ARGS_ASSERT_GROK_NUMERIC_RADIX;
if (*sp < send && **sp == '.') {
++*sp;
return TRUE;
}
return FALSE;
}
/*
=for apidoc grok_number
Recognise (or not) a number. The type of the number is returned
(0 if unrecognised), otherwise it is a bit-ORed combination of
IS_NUMBER_IN_UV, IS_NUMBER_GREATER_THAN_UV_MAX, IS_NUMBER_NOT_INT,
IS_NUMBER_NEG, IS_NUMBER_INFINITY, IS_NUMBER_NAN (defined in perl.h).
If the value of the number can fit an in UV, it is returned in the *valuep
IS_NUMBER_IN_UV will be set to indicate that *valuep is valid, IS_NUMBER_IN_UV
will never be set unless *valuep is valid, but *valuep may have been assigned
to during processing even though IS_NUMBER_IN_UV is not set on return.
If valuep is NULL, IS_NUMBER_IN_UV will be set for the same cases as when
valuep is non-NULL, but no actual assignment (or SEGV) will occur.
IS_NUMBER_NOT_INT will be set with IS_NUMBER_IN_UV if trailing decimals were
seen (in which case *valuep gives the true value truncated to an integer), and
IS_NUMBER_NEG if the number is negative (in which case *valuep holds the
absolute value). IS_NUMBER_IN_UV is not set if e notation was used or the
number is larger than a UV.
=cut
*/
int
Perl_grok_number(pTHX_ const char *pv, STRLEN len, UV *valuep)
{
const char *s = pv;
const char * const send = pv + len;
const UV max_div_10 = UV_MAX / 10;
const char max_mod_10 = UV_MAX % 10;
int numtype = 0;
int sawinf = 0;
int sawnan = 0;
PERL_ARGS_ASSERT_GROK_NUMBER;
while (s < send && isSPACE(*s))
s++;
if (s == send) {
return 0;
} else if (*s == '-') {
s++;
numtype = IS_NUMBER_NEG;
}
else if (*s == '+')
s++;
if (s == send)
return 0;
/* next must be digit or the radix separator or beginning of infinity */
if (isDIGIT(*s)) {
/* UVs are at least 32 bits, so the first 9 decimal digits cannot
overflow. */
UV value = *s - '0';
/* This construction seems to be more optimiser friendly.
(without it gcc does the isDIGIT test and the *s - '0' separately)
With it gcc on arm is managing 6 instructions (6 cycles) per digit.
In theory the optimiser could deduce how far to unroll the loop
before checking for overflow. */
if (++s < send) {
int digit = *s - '0';
if (digit >= 0 && digit <= 9) {
value = value * 10 + digit;
if (++s < send) {
digit = *s - '0';
if (digit >= 0 && digit <= 9) {
value = value * 10 + digit;
if (++s < send) {
digit = *s - '0';
if (digit >= 0 && digit <= 9) {
value = value * 10 + digit;
if (++s < send) {
digit = *s - '0';
if (digit >= 0 && digit <= 9) {
value = value * 10 + digit;
if (++s < send) {
digit = *s - '0';
if (digit >= 0 && digit <= 9) {
value = value * 10 + digit;
if (++s < send) {
digit = *s - '0';
if (digit >= 0 && digit <= 9) {
value = value * 10 + digit;
if (++s < send) {
digit = *s - '0';
if (digit >= 0 && digit <= 9) {
value = value * 10 + digit;
if (++s < send) {
digit = *s - '0';
if (digit >= 0 && digit <= 9) {
value = value * 10 + digit;
if (++s < send) {
/* Now got 9 digits, so need to check
each time for overflow. */
digit = *s - '0';
while (digit >= 0 && digit <= 9
&& (value < max_div_10
|| (value == max_div_10
&& digit <= max_mod_10))) {
value = value * 10 + digit;
if (++s < send)
digit = *s - '0';
else
break;
}
if (digit >= 0 && digit <= 9
&& (s < send)) {
/* value overflowed.
skip the remaining digits, don't
worry about setting *valuep. */
do {
s++;
} while (s < send && isDIGIT(*s));
numtype |=
IS_NUMBER_GREATER_THAN_UV_MAX;
goto skip_value;
}
}
}
}
}
}
}
}
}
}
}
}
}
}
}
}
}
}
numtype |= IS_NUMBER_IN_UV;
if (valuep)
*valuep = value;
skip_value:
if (GROK_NUMERIC_RADIX(&s, send)) {
numtype |= IS_NUMBER_NOT_INT;
while (s < send && isDIGIT(*s)) /* optional digits after the radix */
s++;
}
}
else if (GROK_NUMERIC_RADIX(&s, send)) {
numtype |= IS_NUMBER_NOT_INT | IS_NUMBER_IN_UV; /* valuep assigned below */
/* no digits before the radix means we need digits after it */
if (s < send && isDIGIT(*s)) {
do {
s++;
} while (s < send && isDIGIT(*s));
if (valuep) {
/* integer approximation is valid - it's 0. */
*valuep = 0;
}
}
else
return 0;
} else if (*s == 'I' || *s == 'i') {
s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
s++; if (s == send || (*s != 'F' && *s != 'f')) return 0;
s++; if (s < send && (*s == 'I' || *s == 'i')) {
s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
s++; if (s == send || (*s != 'I' && *s != 'i')) return 0;
s++; if (s == send || (*s != 'T' && *s != 't')) return 0;
s++; if (s == send || (*s != 'Y' && *s != 'y')) return 0;
s++;
}
sawinf = 1;
} else if (*s == 'N' || *s == 'n') {
/* XXX TODO: There are signaling NaNs and quiet NaNs. */
s++; if (s == send || (*s != 'A' && *s != 'a')) return 0;
s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
s++;
sawnan = 1;
} else
return 0;
if (sawinf) {
numtype &= IS_NUMBER_NEG; /* Keep track of sign */
numtype |= IS_NUMBER_INFINITY | IS_NUMBER_NOT_INT;
} else if (sawnan) {
numtype &= IS_NUMBER_NEG; /* Keep track of sign */
numtype |= IS_NUMBER_NAN | IS_NUMBER_NOT_INT;
} else if (s < send) {
/* we can have an optional exponent part */
if (*s == 'e' || *s == 'E') {
/* The only flag we keep is sign. Blow away any "it's UV" */
numtype &= IS_NUMBER_NEG;
numtype |= IS_NUMBER_NOT_INT;
s++;
if (s < send && (*s == '-' || *s == '+'))
s++;
if (s < send && isDIGIT(*s)) {
do {
s++;
} while (s < send && isDIGIT(*s));
}
else
return 0;
}
}
while (s < send && isSPACE(*s))
s++;
if (s >= send)
return numtype;
if (len == 10 && memEQ(pv, "0 but true", 10)) {
if (valuep)
*valuep = 0;
return IS_NUMBER_IN_UV;
}
return 0;
}
STATIC NV
S_mulexp10(NV value, I32 exponent)
{
NV result = 1.0;
NV power = 10.0;
bool negative = 0;
I32 bit;
if (exponent == 0)
return value;
if (value == 0)
return (NV)0;
/* On OpenVMS VAX we by default use the D_FLOAT double format,
* and that format does not have *easy* capabilities [1] for
* overflowing doubles 'silently' as IEEE fp does. We also need
* to support G_FLOAT on both VAX and Alpha, and though the exponent
* range is much larger than D_FLOAT it still doesn't do silent
* overflow. Therefore we need to detect early whether we would
* overflow (this is the behaviour of the native string-to-float
* conversion routines, and therefore of native applications, too).
*
* [1] Trying to establish a condition handler to trap floating point
* exceptions is not a good idea. */
/* In UNICOS and in certain Cray models (such as T90) there is no
* IEEE fp, and no way at all from C to catch fp overflows gracefully.
* There is something you can do if you are willing to use some
* inline assembler: the instruction is called DFI-- but that will
* disable *all* floating point interrupts, a little bit too large
* a hammer. Therefore we need to catch potential overflows before
* it's too late. */
#if ((defined(VMS) && !defined(__IEEE_FP)) || defined(_UNICOS)) && defined(NV_MAX_10_EXP)
STMT_START {
const NV exp_v = log10(value);
if (exponent >= NV_MAX_10_EXP || exponent + exp_v >= NV_MAX_10_EXP)
return NV_MAX;
if (exponent < 0) {
if (-(exponent + exp_v) >= NV_MAX_10_EXP)
return 0.0;
while (-exponent >= NV_MAX_10_EXP) {
/* combination does not overflow, but 10^(-exponent) does */
value /= 10;
++exponent;
}
}
} STMT_END;
#endif
if (exponent < 0) {
negative = 1;
exponent = -exponent;
}
for (bit = 1; exponent; bit <<= 1) {
if (exponent & bit) {
exponent ^= bit;
result *= power;
/* Floating point exceptions are supposed to be turned off,
* but if we're obviously done, don't risk another iteration.
*/
if (exponent == 0) break;
}
power *= power;
}
return negative ? value / result : value * result;
}
NV
Perl_my_atof(pTHX_ const char* s)
{
NV x = 0.0;
#ifdef USE_LOCALE_NUMERIC
dVAR;
PERL_ARGS_ASSERT_MY_ATOF;
if (PL_numeric_local && IN_LOCALE) {
NV y;
/* Scan the number twice; once using locale and once without;
* choose the larger result (in absolute value). */
Perl_atof2(s, x);
SET_NUMERIC_STANDARD();
Perl_atof2(s, y);
SET_NUMERIC_LOCAL();
if ((y < 0.0 && y < x) || (y > 0.0 && y > x))
return y;
}
else
Perl_atof2(s, x);
#else
Perl_atof2(s, x);
#endif
return x;
}
char*
Perl_my_atof2(pTHX_ const char* orig, NV* value)
{
NV result[3] = {0.0, 0.0, 0.0};
const char* s = orig;
#ifdef USE_PERL_ATOF
UV accumulator[2] = {0,0}; /* before/after dp */
bool negative = 0;
const char* send = s + strlen(orig) - 1;
bool seen_digit = 0;
I32 exp_adjust[2] = {0,0};
I32 exp_acc[2] = {-1, -1};
/* the current exponent adjust for the accumulators */
I32 exponent = 0;
I32 seen_dp = 0;
I32 digit = 0;
I32 old_digit = 0;
I32 sig_digits = 0; /* noof significant digits seen so far */
PERL_ARGS_ASSERT_MY_ATOF2;
/* There is no point in processing more significant digits
* than the NV can hold. Note that NV_DIG is a lower-bound value,
* while we need an upper-bound value. We add 2 to account for this;
* since it will have been conservative on both the first and last digit.
* For example a 32-bit mantissa with an exponent of 4 would have
* exact values in the set
* 4
* 8
* ..
* 17179869172
* 17179869176
* 17179869180
*
* where for the purposes of calculating NV_DIG we would have to discount
* both the first and last digit, since neither can hold all values from
* 0..9; but for calculating the value we must examine those two digits.
*/
#ifdef MAX_SIG_DIG_PLUS
/* It is not necessarily the case that adding 2 to NV_DIG gets all the
possible digits in a NV, especially if NVs are not IEEE compliant
(e.g., long doubles on IRIX) - Allen <allens@cpan.org> */
# define MAX_SIG_DIGITS (NV_DIG+MAX_SIG_DIG_PLUS)
#else
# define MAX_SIG_DIGITS (NV_DIG+2)
#endif
/* the max number we can accumulate in a UV, and still safely do 10*N+9 */
#define MAX_ACCUMULATE ( (UV) ((UV_MAX - 9)/10))
/* leading whitespace */
while (isSPACE(*s))
++s;
/* sign */
switch (*s) {
case '-':
negative = 1;
/* fall through */
case '+':
++s;
}
/* punt to strtod for NaN/Inf; if no support for it there, tough luck */
#ifdef HAS_STRTOD
if (*s == 'n' || *s == 'N' || *s == 'i' || *s == 'I') {
const char *p = negative ? s - 1 : s;
char *endp;
NV rslt;
rslt = strtod(p, &endp);
if (endp != p) {
*value = rslt;
return (char *)endp;
}
}
#endif
/* we accumulate digits into an integer; when this becomes too
* large, we add the total to NV and start again */
while (1) {
if (isDIGIT(*s)) {
seen_digit = 1;
old_digit = digit;
digit = *s++ - '0';
if (seen_dp)
exp_adjust[1]++;
/* don't start counting until we see the first significant
* digit, eg the 5 in 0.00005... */
if (!sig_digits && digit == 0)
continue;
if (++sig_digits > MAX_SIG_DIGITS) {
/* limits of precision reached */
if (digit > 5) {
++accumulator[seen_dp];
} else if (digit == 5) {
if (old_digit % 2) { /* round to even - Allen */
++accumulator[seen_dp];
}
}
if (seen_dp) {
exp_adjust[1]--;
} else {
exp_adjust[0]++;
}
/* skip remaining digits */
while (isDIGIT(*s)) {
++s;
if (! seen_dp) {
exp_adjust[0]++;
}
}
/* warn of loss of precision? */
}
else {
if (accumulator[seen_dp] > MAX_ACCUMULATE) {
/* add accumulator to result and start again */
result[seen_dp] = S_mulexp10(result[seen_dp],
exp_acc[seen_dp])
+ (NV)accumulator[seen_dp];
accumulator[seen_dp] = 0;
exp_acc[seen_dp] = 0;
}
accumulator[seen_dp] = accumulator[seen_dp] * 10 + digit;
++exp_acc[seen_dp];
}
}
else if (!seen_dp && GROK_NUMERIC_RADIX(&s, send)) {
seen_dp = 1;
if (sig_digits > MAX_SIG_DIGITS) {
do {
++s;
} while (isDIGIT(*s));
break;
}
}
else {
break;
}
}
result[0] = S_mulexp10(result[0], exp_acc[0]) + (NV)accumulator[0];
if (seen_dp) {
result[1] = S_mulexp10(result[1], exp_acc[1]) + (NV)accumulator[1];
}