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NetBSD/gnu/dist/gas/atof-generic.c

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/* atof_generic.c - turn a string of digits into a Flonum
Copyright (C) 1987, 90, 91, 92, 93, 94, 95, 96, 1998
Free Software Foundation, Inc.
This file is part of GAS, the GNU Assembler.
GAS is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
GAS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GAS; see the file COPYING. If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
#include <ctype.h>
#include <string.h>
#include "as.h"
#ifndef FALSE
#define FALSE (0)
#endif
#ifndef TRUE
#define TRUE (1)
#endif
#ifdef TRACE
static void flonum_print PARAMS ((const FLONUM_TYPE *));
#endif
#define ASSUME_DECIMAL_MARK_IS_DOT
/***********************************************************************\
* *
* Given a string of decimal digits , with optional decimal *
* mark and optional decimal exponent (place value) of the *
* lowest_order decimal digit: produce a floating point *
* number. The number is 'generic' floating point: our *
* caller will encode it for a specific machine architecture. *
* *
* Assumptions *
* uses base (radix) 2 *
* this machine uses 2's complement binary integers *
* target flonums use " " " " *
* target flonums exponents fit in a long *
* *
\***********************************************************************/
/*
Syntax:
<flonum> ::= <optional-sign> <decimal-number> <optional-exponent>
<optional-sign> ::= '+' | '-' | {empty}
<decimal-number> ::= <integer>
| <integer> <radix-character>
| <integer> <radix-character> <integer>
| <radix-character> <integer>
<optional-exponent> ::= {empty}
| <exponent-character> <optional-sign> <integer>
<integer> ::= <digit> | <digit> <integer>
<digit> ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'
<exponent-character> ::= {one character from "string_of_decimal_exponent_marks"}
<radix-character> ::= {one character from "string_of_decimal_marks"}
*/
int
atof_generic (address_of_string_pointer,
string_of_decimal_marks,
string_of_decimal_exponent_marks,
address_of_generic_floating_point_number)
/* return pointer to just AFTER number we read. */
char **address_of_string_pointer;
/* At most one per number. */
const char *string_of_decimal_marks;
const char *string_of_decimal_exponent_marks;
FLONUM_TYPE *address_of_generic_floating_point_number;
{
int return_value; /* 0 means OK. */
char *first_digit;
unsigned int number_of_digits_before_decimal;
unsigned int number_of_digits_after_decimal;
long decimal_exponent;
unsigned int number_of_digits_available;
char digits_sign_char;
/*
* Scan the input string, abstracting (1)digits (2)decimal mark (3) exponent.
* It would be simpler to modify the string, but we don't; just to be nice
* to caller.
* We need to know how many digits we have, so we can allocate space for
* the digits' value.
*/
char *p;
char c;
int seen_significant_digit;
#ifdef ASSUME_DECIMAL_MARK_IS_DOT
assert (string_of_decimal_marks[0] == '.'
&& string_of_decimal_marks[1] == 0);
#define IS_DECIMAL_MARK(c) ((c) == '.')
#else
#define IS_DECIMAL_MARK(c) (0 != strchr (string_of_decimal_marks, (c)))
#endif
first_digit = *address_of_string_pointer;
c = *first_digit;
if (c == '-' || c == '+')
{
digits_sign_char = c;
first_digit++;
}
else
digits_sign_char = '+';
switch (first_digit[0])
{
case 'n':
case 'N':
if (!strncasecmp ("nan", first_digit, 3))
{
address_of_generic_floating_point_number->sign = 0;
address_of_generic_floating_point_number->exponent = 0;
address_of_generic_floating_point_number->leader =
address_of_generic_floating_point_number->low;
*address_of_string_pointer = first_digit + 3;
return 0;
}
break;
case 'i':
case 'I':
if (!strncasecmp ("inf", first_digit, 3))
{
address_of_generic_floating_point_number->sign =
digits_sign_char == '+' ? 'P' : 'N';
address_of_generic_floating_point_number->exponent = 0;
address_of_generic_floating_point_number->leader =
address_of_generic_floating_point_number->low;
first_digit += 3;
if (!strncasecmp ("inity", first_digit, 5))
first_digit += 5;
*address_of_string_pointer = first_digit;
return 0;
}
break;
}
number_of_digits_before_decimal = 0;
number_of_digits_after_decimal = 0;
decimal_exponent = 0;
seen_significant_digit = 0;
for (p = first_digit;
(((c = *p) != '\0')
&& (!c || !IS_DECIMAL_MARK (c))
&& (!c || !strchr (string_of_decimal_exponent_marks, c)));
p++)
{
if (isdigit ((unsigned char) c))
{
if (seen_significant_digit || c > '0')
{
++number_of_digits_before_decimal;
seen_significant_digit = 1;
}
else
{
first_digit++;
}
}
else
{
break; /* p -> char after pre-decimal digits. */
}
} /* For each digit before decimal mark. */
#ifndef OLD_FLOAT_READS
/* Ignore trailing 0's after the decimal point. The original code here
* (ifdef'd out) does not do this, and numbers like
* 4.29496729600000000000e+09 (2**31)
* come out inexact for some reason related to length of the digit
* string.
*/
if (c && IS_DECIMAL_MARK (c))
{
unsigned int zeros = 0; /* Length of current string of zeros */
for (p++; (c = *p) && isdigit ((unsigned char) c); p++)
{
if (c == '0')
{
zeros++;
}
else
{
number_of_digits_after_decimal += 1 + zeros;
zeros = 0;
}
}
}
#else
if (c && IS_DECIMAL_MARK (c))
{
for (p++;
(((c = *p) != '\0')
&& (!c || !strchr (string_of_decimal_exponent_marks, c)));
p++)
{
if (isdigit (c))
{
/* This may be retracted below. */
number_of_digits_after_decimal++;
if ( /* seen_significant_digit || */ c > '0')
{
seen_significant_digit = TRUE;
}
}
else
{
if (!seen_significant_digit)
{
number_of_digits_after_decimal = 0;
}
break;
}
} /* For each digit after decimal mark. */
}
while (number_of_digits_after_decimal
&& first_digit[number_of_digits_before_decimal
+ number_of_digits_after_decimal] == '0')
--number_of_digits_after_decimal;
#endif
if (flag_m68k_mri)
{
while (c == '_')
c = *++p;
}
if (c && strchr (string_of_decimal_exponent_marks, c))
{
char digits_exponent_sign_char;
c = *++p;
if (flag_m68k_mri)
{
while (c == '_')
c = *++p;
}
if (c && strchr ("+-", c))
{
digits_exponent_sign_char = c;
c = *++p;
}
else
{
digits_exponent_sign_char = '+';
}
for (; (c); c = *++p)
{
if (isdigit ((unsigned char) c))
{
decimal_exponent = decimal_exponent * 10 + c - '0';
/*
* BUG! If we overflow here, we lose!
*/
}
else
{
break;
}
}
if (digits_exponent_sign_char == '-')
{
decimal_exponent = -decimal_exponent;
}
}
*address_of_string_pointer = p;
number_of_digits_available =
number_of_digits_before_decimal + number_of_digits_after_decimal;
return_value = 0;
if (number_of_digits_available == 0)
{
address_of_generic_floating_point_number->exponent = 0; /* Not strictly necessary */
address_of_generic_floating_point_number->leader
= -1 + address_of_generic_floating_point_number->low;
address_of_generic_floating_point_number->sign = digits_sign_char;
/* We have just concocted (+/-)0.0E0 */
}
else
{
int count; /* Number of useful digits left to scan. */
LITTLENUM_TYPE *digits_binary_low;
unsigned int precision;
unsigned int maximum_useful_digits;
unsigned int number_of_digits_to_use;
unsigned int more_than_enough_bits_for_digits;
unsigned int more_than_enough_littlenums_for_digits;
unsigned int size_of_digits_in_littlenums;
unsigned int size_of_digits_in_chars;
FLONUM_TYPE power_of_10_flonum;
FLONUM_TYPE digits_flonum;
precision = (address_of_generic_floating_point_number->high
- address_of_generic_floating_point_number->low
+ 1); /* Number of destination littlenums. */
/* Includes guard bits (two littlenums worth) */
#if 0 /* The integer version below is very close, and it doesn't
require floating point support (which is currently buggy on
the Alpha). */
maximum_useful_digits = (((double) (precision - 2))
* ((double) (LITTLENUM_NUMBER_OF_BITS))
/ (LOG_TO_BASE_2_OF_10))
+ 2; /* 2 :: guard digits. */
#else
maximum_useful_digits = (((precision - 2))
* ( (LITTLENUM_NUMBER_OF_BITS))
* 1000000 / 3321928)
+ 2; /* 2 :: guard digits. */
#endif
if (number_of_digits_available > maximum_useful_digits)
{
number_of_digits_to_use = maximum_useful_digits;
}
else
{
number_of_digits_to_use = number_of_digits_available;
}
/* Cast these to SIGNED LONG first, otherwise, on systems with
LONG wider than INT (such as Alpha OSF/1), unsignedness may
cause unexpected results. */
decimal_exponent += ((long) number_of_digits_before_decimal
- (long) number_of_digits_to_use);
#if 0
more_than_enough_bits_for_digits
= ((((double) number_of_digits_to_use) * LOG_TO_BASE_2_OF_10) + 1);
#else
more_than_enough_bits_for_digits
= (number_of_digits_to_use * 3321928 / 1000000 + 1);
#endif
more_than_enough_littlenums_for_digits
= (more_than_enough_bits_for_digits
/ LITTLENUM_NUMBER_OF_BITS)
+ 2;
/* Compute (digits) part. In "12.34E56" this is the "1234" part.
Arithmetic is exact here. If no digits are supplied then this
part is a 0 valued binary integer. Allocate room to build up
the binary number as littlenums. We want this memory to
disappear when we leave this function. Assume no alignment
problems => (room for n objects) == n * (room for 1
object). */
size_of_digits_in_littlenums = more_than_enough_littlenums_for_digits;
size_of_digits_in_chars = size_of_digits_in_littlenums
* sizeof (LITTLENUM_TYPE);
digits_binary_low = (LITTLENUM_TYPE *)
alloca (size_of_digits_in_chars);
memset ((char *) digits_binary_low, '\0', size_of_digits_in_chars);
/* Digits_binary_low[] is allocated and zeroed. */
/*
* Parse the decimal digits as if * digits_low was in the units position.
* Emit a binary number into digits_binary_low[].
*
* Use a large-precision version of:
* (((1st-digit) * 10 + 2nd-digit) * 10 + 3rd-digit ...) * 10 + last-digit
*/
for (p = first_digit, count = number_of_digits_to_use; count; p++, --count)
{
c = *p;
if (isdigit ((unsigned char) c))
{
/*
* Multiply by 10. Assume can never overflow.
* Add this digit to digits_binary_low[].
*/
long carry;
LITTLENUM_TYPE *littlenum_pointer;
LITTLENUM_TYPE *littlenum_limit;
littlenum_limit = digits_binary_low
+ more_than_enough_littlenums_for_digits
- 1;
carry = c - '0'; /* char -> binary */
for (littlenum_pointer = digits_binary_low;
littlenum_pointer <= littlenum_limit;
littlenum_pointer++)
{
long work;
work = carry + 10 * (long) (*littlenum_pointer);
*littlenum_pointer = work & LITTLENUM_MASK;
carry = work >> LITTLENUM_NUMBER_OF_BITS;
}
if (carry != 0)
{
/*
* We have a GROSS internal error.
* This should never happen.
*/
as_fatal ("failed sanity check.");
}
}
else
{
++count; /* '.' doesn't alter digits used count. */
}
}
/*
* Digits_binary_low[] properly encodes the value of the digits.
* Forget about any high-order littlenums that are 0.
*/
while (digits_binary_low[size_of_digits_in_littlenums - 1] == 0
&& size_of_digits_in_littlenums >= 2)
size_of_digits_in_littlenums--;
digits_flonum.low = digits_binary_low;
digits_flonum.high = digits_binary_low + size_of_digits_in_littlenums - 1;
digits_flonum.leader = digits_flonum.high;
digits_flonum.exponent = 0;
/*
* The value of digits_flonum . sign should not be important.
* We have already decided the output's sign.
* We trust that the sign won't influence the other parts of the number!
* So we give it a value for these reasons:
* (1) courtesy to humans reading/debugging
* these numbers so they don't get excited about strange values
* (2) in future there may be more meaning attached to sign,
* and what was
* harmless noise may become disruptive, ill-conditioned (or worse)
* input.
*/
digits_flonum.sign = '+';
{
/*
* Compute the mantssa (& exponent) of the power of 10.
* If sucessful, then multiply the power of 10 by the digits
* giving return_binary_mantissa and return_binary_exponent.
*/
LITTLENUM_TYPE *power_binary_low;
int decimal_exponent_is_negative;
/* This refers to the "-56" in "12.34E-56". */
/* FALSE: decimal_exponent is positive (or 0) */
/* TRUE: decimal_exponent is negative */
FLONUM_TYPE temporary_flonum;
LITTLENUM_TYPE *temporary_binary_low;
unsigned int size_of_power_in_littlenums;
unsigned int size_of_power_in_chars;
size_of_power_in_littlenums = precision;
/* Precision has a built-in fudge factor so we get a few guard bits. */
decimal_exponent_is_negative = decimal_exponent < 0;
if (decimal_exponent_is_negative)
{
decimal_exponent = -decimal_exponent;
}
/* From now on: the decimal exponent is > 0. Its sign is separate. */
size_of_power_in_chars = size_of_power_in_littlenums
* sizeof (LITTLENUM_TYPE) + 2;
power_binary_low = (LITTLENUM_TYPE *) alloca (size_of_power_in_chars);
temporary_binary_low = (LITTLENUM_TYPE *) alloca (size_of_power_in_chars);
memset ((char *) power_binary_low, '\0', size_of_power_in_chars);
*power_binary_low = 1;
power_of_10_flonum.exponent = 0;
power_of_10_flonum.low = power_binary_low;
power_of_10_flonum.leader = power_binary_low;
power_of_10_flonum.high = power_binary_low + size_of_power_in_littlenums - 1;
power_of_10_flonum.sign = '+';
temporary_flonum.low = temporary_binary_low;
temporary_flonum.high = temporary_binary_low + size_of_power_in_littlenums - 1;
/*
* (power) == 1.
* Space for temporary_flonum allocated.
*/
/*
* ...
*
* WHILE more bits
* DO find next bit (with place value)
* multiply into power mantissa
* OD
*/
{
int place_number_limit;
/* Any 10^(2^n) whose "n" exceeds this */
/* value will fall off the end of */
/* flonum_XXXX_powers_of_ten[]. */
int place_number;
const FLONUM_TYPE *multiplicand; /* -> 10^(2^n) */
place_number_limit = table_size_of_flonum_powers_of_ten;
multiplicand = (decimal_exponent_is_negative
? flonum_negative_powers_of_ten
: flonum_positive_powers_of_ten);
for (place_number = 1;/* Place value of this bit of exponent. */
decimal_exponent;/* Quit when no more 1 bits in exponent. */
decimal_exponent >>= 1, place_number++)
{
if (decimal_exponent & 1)
{
if (place_number > place_number_limit)
{
/* The decimal exponent has a magnitude so great
that our tables can't help us fragment it.
Although this routine is in error because it
can't imagine a number that big, signal an
error as if it is the user's fault for
presenting such a big number. */
return_value = ERROR_EXPONENT_OVERFLOW;
/* quit out of loop gracefully */
decimal_exponent = 0;
}
else
{
#ifdef TRACE
printf ("before multiply, place_number = %d., power_of_10_flonum:\n",
place_number);
flonum_print (&power_of_10_flonum);
(void) putchar ('\n');
#endif
#ifdef TRACE
printf ("multiplier:\n");
flonum_print (multiplicand + place_number);
(void) putchar ('\n');
#endif
flonum_multip (multiplicand + place_number,
&power_of_10_flonum, &temporary_flonum);
#ifdef TRACE
printf ("after multiply:\n");
flonum_print (&temporary_flonum);
(void) putchar ('\n');
#endif
flonum_copy (&temporary_flonum, &power_of_10_flonum);
#ifdef TRACE
printf ("after copy:\n");
flonum_print (&power_of_10_flonum);
(void) putchar ('\n');
#endif
} /* If this bit of decimal_exponent was computable.*/
} /* If this bit of decimal_exponent was set. */
} /* For each bit of binary representation of exponent */
#ifdef TRACE
printf ("after computing power_of_10_flonum:\n");
flonum_print (&power_of_10_flonum);
(void) putchar ('\n');
#endif
}
}
/*
* power_of_10_flonum is power of ten in binary (mantissa) , (exponent).
* It may be the number 1, in which case we don't NEED to multiply.
*
* Multiply (decimal digits) by power_of_10_flonum.
*/
flonum_multip (&power_of_10_flonum, &digits_flonum, address_of_generic_floating_point_number);
/* Assert sign of the number we made is '+'. */
address_of_generic_floating_point_number->sign = digits_sign_char;
}
return return_value;
}
#ifdef TRACE
static void
flonum_print (f)
const FLONUM_TYPE *f;
{
LITTLENUM_TYPE *lp;
char littlenum_format[10];
sprintf (littlenum_format, " %%0%dx", sizeof (LITTLENUM_TYPE) * 2);
#define print_littlenum(LP) (printf (littlenum_format, LP))
printf ("flonum @%p %c e%ld", f, f->sign, f->exponent);
if (f->low < f->high)
for (lp = f->high; lp >= f->low; lp--)
print_littlenum (*lp);
else
for (lp = f->low; lp <= f->high; lp++)
print_littlenum (*lp);
printf ("\n");
fflush (stdout);
}
#endif
/* end of atof_generic.c */
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