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(FLOAT_MIN_10_EXP, FLOAT_MIN_10_NORM): Define. (ecvt_r): Special case denormals.

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This commit is contained in:
Ulrich Drepper
2004-12-22 19:55:46 +00:00
parent 3b7a95fb6b
commit ec8c29dc01
1 changed files with 24 additions and 1 deletions
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25
misc/efgcvt_r.c
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@@ -1,5 +1,5 @@
/* Compatibility functions for floating point formatting, reentrant versions. /* Compatibility functions for floating point formatting, reentrant versions.
Copyright (C) 1995,96,97,98,99,2000,01,02 Free Software Foundation, Inc. Copyright (C) 1995,96,97,98,99,2000,01,02,04 Free Software Foundation, Inc.
This file is part of the GNU C Library. This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or The GNU C Library is free software; you can redistribute it and/or
@@ -31,6 +31,7 @@
# define FUNC_PREFIX # define FUNC_PREFIX
# define FLOAT_FMT_FLAG # define FLOAT_FMT_FLAG
# define FLOAT_NAME_EXT # define FLOAT_NAME_EXT
# define FLOAT_MIN_10_EXP DBL_MIN_10_EXP
# if DBL_MANT_DIG == 53 # if DBL_MANT_DIG == 53
# define NDIGIT_MAX 17 # define NDIGIT_MAX 17
# elif DBL_MANT_DIG == 24 # elif DBL_MANT_DIG == 24
@@ -43,6 +44,17 @@
# error "NDIGIT_MAX must be precomputed" # error "NDIGIT_MAX must be precomputed"
# define NDIGIT_MAX (lrint (ceil (M_LN2 / M_LN10 * DBL_MANT_DIG + 1.0))) # define NDIGIT_MAX (lrint (ceil (M_LN2 / M_LN10 * DBL_MANT_DIG + 1.0)))
# endif # endif
# if DBL_MIN_10_EXP == -37
# define FLOAT_MIN_10_NORM 1.0e-37
# elif DBL_MIN_10_EXP == -307
# define FLOAT_MIN_10_NORM 1.0e-307
# elif DBL_MIN_10_EXP == -4931
# define FLOAT_MIN_10_NORM 1.0e-4931
# else
/* libc can't depend on libm. */
# error "FLOAT_MIN_10_NORM must be precomputed"
# define FLOAT_MIN_10_NORM exp10 (DBL_MIN_10_EXP)
# endif
#endif #endif
#define APPEND(a, b) APPEND2 (a, b) #define APPEND(a, b) APPEND2 (a, b)
@@ -171,6 +183,17 @@ APPEND (FUNC_PREFIX, ecvt_r) (value, ndigit, decpt, sign, buf, len)
d = -value; d = -value;
else else
d = value; d = value;
/* For denormalized numbers the d < 1.0 case below won't work,
as f can overflow to +Inf. */
if (d < FLOAT_MIN_10_NORM)
{
value /= FLOAT_MIN_10_NORM;
if (value < 0.0)
d = -value;
else
d = value;
exponent += FLOAT_MIN_10_EXP;
}
if (d < 1.0) if (d < 1.0)
{ {
do do