newlib-cygwin/newlib/libm/mathfp/s_ldexp.c

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/* @(#)z_ldexp.c 1.0 98/08/13 */
/*
FUNCTION
<<ldexp>>, <<ldexpf>>---load exponent
INDEX
ldexp
INDEX
ldexpf
ANSI_SYNOPSIS
#include <math.h>
double ldexp(double <[val]>, int <[exp]>);
float ldexpf(float <[val]>, int <[exp]>);
TRAD_SYNOPSIS
#include <math.h>
double ldexp(<[val]>, <[exp]>)
double <[val]>;
int <[exp]>;
float ldexpf(<[val]>, <[exp]>)
float <[val]>;
int <[exp]>;
DESCRIPTION
<<ldexp>> calculates the value
2003-10-20 Bob Wilson <bob.wilson@acm.org> * libc/locale/locale.c: Use double quotes in code. * libc/locale/locale.tex: Likewise. * libc/libc.texinfo: Hyphenate "floating-point". * libc/machine/necv70/necv70.tex: Likewise. * libc/stdio/sprintf.c: Likewise. * libc/stdio/sscanf.c: Likewise. * libc/stdlib/atof.c: Likewise. * libc/stdlib/ldtoa.c: Fix comment typo. * libc/stdlib/div.c: Use @ifnottex instead of @ifinfo. * libc/stdlib/ldiv.c: Likewise. * libm/common/s_expm1.c: Likewise. * libm/common/s_ilogb.c: Hyphenate "floating-point". Use "nonzero". * libm/common/s_infinity: Hyphenate "double- and single-precision". * libm/common/s_nan.c: Likewise. Also correct the FUNCTION summary. * libm/common/s_nextafter.c: Fix typo. Hyphenate "double-precision" and "floating-point". * libm/common/s_scalbn.c: Correct the FUNCTION summary. * libm/math/e_pow.c: Fix comment typo. * libm/math/math.tex: Hyphenate "single-precision" and "floating-point". * libm/math/s_asinh.c: Use @ifnottex instead of @ifinfo. * libm/math/s_atan.c: Likewise. * libm/math/s_frexp.c: Likewise. Also use "nonzero". * libm/math/s_isnan.c: Hyphenate "single-precision" and "floating-point". Use "nonzero". * libm/math/s_ldexp.c: Use @ifnottex instead of @ifinfo. * libm/math/w_acos.c: Likewise. * libm/math/w_acosh.c: Likewise. * libm/math/w_asin.c: Likewise. * libm/math/w_atan2.c: Likewise. * libm/math/w_atanh.c: Likewise. * libm/math/w_cosh.c: Likewise. * libm/math/w_exp.c: Likewise. * libm/math/w_exp2.c: Likewise. Add missing @end and missing @tex version of 2^x in the description. * libm/math/w_fmod.c: Use @ifnottex instead of @ifinfo. * libm/math/w_gamma.c: Likewise. * libm/math/w_hypot.c: Likewise. * libm/math/w_j0.c: Likewise. * libm/math/w_sinh.c: Likewise. * libm/math/w_pow.c: Replace "exp1.0nt" with "exponent". * libm/mathfp/mathfp.tex: Hyphenate "single-precision" and "floating-point". * libm/mathfp/e_acosh.c: Use @ifnottex instead of @ifinfo. * libm/mathfp/e_atanh.c: Likewise. * libm/mathfp/e_hypot.c: Likewise. * libm/mathfp/er_lgamma.c: Likewise. * libm/mathfp/s_acos.c: Likewise. * libm/mathfp/s_asine.c: Likewise. * libm/mathfp/s_asinh.c: Likewise. * libm/mathfp/s_atan.c: Likewise. * libm/mathfp/s_atan2.c: Likewise. * libm/mathfp/s_atangent.c: Likewise. * libm/mathfp/s_cosh.c: Likewise. * libm/mathfp/s_exp.c: Likewise. * libm/mathfp/s_fmod.c: Likewise. * libm/mathfp/s_frexp.c: Likewise. Also use "nonzero". * libm/mathfp/s_isnan.c: Hyphenate "single-precision" and "floating-point". Use "nonzero". * libm/math/s_pow.c: Replace "exp1.0nt" with "exponent". * libm/mathfp/s_ldexp.c: Use @ifnottex instead of @ifinfo. * libm/mathfp/s_sineh.c: Likewise. * libm/mathfp/w_jn.c: Likewise.
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@ifnottex
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<[val]> times 2 to the power <[exp]>.
2003-10-20 Bob Wilson <bob.wilson@acm.org> * libc/locale/locale.c: Use double quotes in code. * libc/locale/locale.tex: Likewise. * libc/libc.texinfo: Hyphenate "floating-point". * libc/machine/necv70/necv70.tex: Likewise. * libc/stdio/sprintf.c: Likewise. * libc/stdio/sscanf.c: Likewise. * libc/stdlib/atof.c: Likewise. * libc/stdlib/ldtoa.c: Fix comment typo. * libc/stdlib/div.c: Use @ifnottex instead of @ifinfo. * libc/stdlib/ldiv.c: Likewise. * libm/common/s_expm1.c: Likewise. * libm/common/s_ilogb.c: Hyphenate "floating-point". Use "nonzero". * libm/common/s_infinity: Hyphenate "double- and single-precision". * libm/common/s_nan.c: Likewise. Also correct the FUNCTION summary. * libm/common/s_nextafter.c: Fix typo. Hyphenate "double-precision" and "floating-point". * libm/common/s_scalbn.c: Correct the FUNCTION summary. * libm/math/e_pow.c: Fix comment typo. * libm/math/math.tex: Hyphenate "single-precision" and "floating-point". * libm/math/s_asinh.c: Use @ifnottex instead of @ifinfo. * libm/math/s_atan.c: Likewise. * libm/math/s_frexp.c: Likewise. Also use "nonzero". * libm/math/s_isnan.c: Hyphenate "single-precision" and "floating-point". Use "nonzero". * libm/math/s_ldexp.c: Use @ifnottex instead of @ifinfo. * libm/math/w_acos.c: Likewise. * libm/math/w_acosh.c: Likewise. * libm/math/w_asin.c: Likewise. * libm/math/w_atan2.c: Likewise. * libm/math/w_atanh.c: Likewise. * libm/math/w_cosh.c: Likewise. * libm/math/w_exp.c: Likewise. * libm/math/w_exp2.c: Likewise. Add missing @end and missing @tex version of 2^x in the description. * libm/math/w_fmod.c: Use @ifnottex instead of @ifinfo. * libm/math/w_gamma.c: Likewise. * libm/math/w_hypot.c: Likewise. * libm/math/w_j0.c: Likewise. * libm/math/w_sinh.c: Likewise. * libm/math/w_pow.c: Replace "exp1.0nt" with "exponent". * libm/mathfp/mathfp.tex: Hyphenate "single-precision" and "floating-point". * libm/mathfp/e_acosh.c: Use @ifnottex instead of @ifinfo. * libm/mathfp/e_atanh.c: Likewise. * libm/mathfp/e_hypot.c: Likewise. * libm/mathfp/er_lgamma.c: Likewise. * libm/mathfp/s_acos.c: Likewise. * libm/mathfp/s_asine.c: Likewise. * libm/mathfp/s_asinh.c: Likewise. * libm/mathfp/s_atan.c: Likewise. * libm/mathfp/s_atan2.c: Likewise. * libm/mathfp/s_atangent.c: Likewise. * libm/mathfp/s_cosh.c: Likewise. * libm/mathfp/s_exp.c: Likewise. * libm/mathfp/s_fmod.c: Likewise. * libm/mathfp/s_frexp.c: Likewise. Also use "nonzero". * libm/mathfp/s_isnan.c: Hyphenate "single-precision" and "floating-point". Use "nonzero". * libm/math/s_pow.c: Replace "exp1.0nt" with "exponent". * libm/mathfp/s_ldexp.c: Use @ifnottex instead of @ifinfo. * libm/mathfp/s_sineh.c: Likewise. * libm/mathfp/w_jn.c: Likewise.
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@end ifnottex
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@tex
$val\times 2^{exp}$.
@end tex
<<ldexpf>> is identical, save that it takes and returns <<float>>
rather than <<double>> values.
RETURNS
<<ldexp>> returns the calculated value.
Underflow and overflow both set <<errno>> to <<ERANGE>>.
On underflow, <<ldexp>> and <<ldexpf>> return 0.0.
On overflow, <<ldexp>> returns plus or minus <<HUGE_VAL>>.
PORTABILITY
2005-10-28 Bob Wilson <bob.wilson@acm.org> * libc/misc/unctrl.c: Replace FUNCTION description. * libc/signal/signal.c: Remove documentation for raise and _raise_r. * libc/stdio/getdelim.c: Fix spelling errors. * libc/stdio/getw.c: Put RETURNS on a separate line. Fix punctuation. * libc/stdio/putw.c: Likewise. * libc/stdlib/a64l.c: Fix formatting, spelling and punctuation in documentation. * libc/stdlib/assert.c: Do not capitalize FUNCTION description. * libc/stdlib/efgcvt.c: Add spaces to FUNCTION description. * libc/stdlib/envlock.c: Use em-dash in FUNCTION description. * libc/stdlib/mlock.c: Likewise. * libc/stdlib/mstats.c: Likewise. * libc/time/tzlock.c: Likewise. * libc/stdlib/rand.c: Use "multi-threaded" and "thread-safe" in NOTES. * libc/stdlib/rand48.c: Remove extra space in FUNCTION description and hyphenate "pseudo-random". * libc/string/bcmp.c: Remove extra blank lines in documentation. * libc/string/strncat.c: Likewise. * libc/string/memchr.c: Remove extra ">" character in documentation. * libc/string/strcspn.c: Use "characters" instead of "chars". * libc/string/strpbrk.c: Likewise. * libc/string/strerror_r.c: Capitalize "GNU". * libc/string/strnlen.c: Likewise. * libc/string/strtok.c: Fix formatting, spelling and punctuation in documentation. Use "multi-threaded" and "thread-safe" in NOTES. * libc/string/wcscat.c: Split PORTABILITY into two paragraphs. * libc/string/wcschr.c: Likewise. * libc/string/wcscmp.c: Likewise. * libc/string/wcscpy.c: Likewise. * libc/string/wcscspn.c: Likewise. * libc/string/wcslen.c: Likewise. * libc/string/wcsncat.c: Likewise. * libc/string/wcsncmp.c: Likewise. * libc/string/wcsncpy.c: Likewise. * libc/string/wcsnlen.c: Likewise. * libc/string/wcspbrk.c: Likewise. * libc/string/wcsrchr.c: Likewise. * libc/string/wcsspn.c: Likewise. * libc/string/wmemchr.c: Likewise. * libc/string/wmemcmp.c: Likewise. * libc/string/wmemcpy.c: Likewise. * libc/string/wmemset.c: Likewise. * libc/string/wmemmove.c: Likewise. Also fix FUNCTION description. * libc/string/wcswidth.c: Formatting and punctuation in documentation. * libc/string/wcwidth.c: Likewise. * libm/common/s_modf.c: Remove extra period from documentation. * libm/math/s_isnan.c: Fix formatting, grammar and punctuation in documentation. * libm/mathfp/s_isnan.c: Likewise. * libm/math/s_ldexp.c: Fix punctuation. * libm/mathfp/s_ldexp.c: Likewise. * libm/math/w_log.c: Likewise. * libm/mathfp/s_logarithm.c: Likewise. * libm/math/w_j0.c: Add spaces to FUNCTION description. * libm/mathfp/w_jn.c: Likewise.
2005-10-29 05:21:08 +08:00
<<ldexp>> is ANSI. <<ldexpf>> is an extension.
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*/
/******************************************************************
* ldexp
*
* Input:
* d - a floating point value
* e - an exponent value
*
* Output:
* A floating point value f such that f = d * 2 ^ e.
*
* Description:
* This function creates a floating point number f such that
* f = d * 2 ^ e.
*
*****************************************************************/
#include <float.h>
#include "fdlibm.h"
#include "zmath.h"
#ifndef _DOUBLE_IS_32BITS
#define DOUBLE_EXP_OFFS 1023
double
_DEFUN (ldexp, (double, int),
double d _AND
int e)
{
int exp;
__uint32_t hd;
GET_HIGH_WORD (hd, d);
/* Check for special values and then scale d by e. */
switch (numtest (d))
{
case NAN:
errno = EDOM;
break;
case INF:
errno = ERANGE;
break;
case 0:
break;
default:
exp = (hd & 0x7ff00000) >> 20;
exp += e;
if (exp > DBL_MAX_EXP + DOUBLE_EXP_OFFS)
{
errno = ERANGE;
d = z_infinity.d;
}
else if (exp < DBL_MIN_EXP + DOUBLE_EXP_OFFS)
{
errno = ERANGE;
d = -z_infinity.d;
}
else
{
hd &= 0x800fffff;
hd |= exp << 20;
SET_HIGH_WORD (d, hd);
}
}
return (d);
}
#endif /* _DOUBLE_IS_32BITS */