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Diffstat (limited to 'newlib/libm/mathfp/s_ldexp.c')
-rw-r--r-- | newlib/libm/mathfp/s_ldexp.c | 123 |
1 files changed, 123 insertions, 0 deletions
diff --git a/newlib/libm/mathfp/s_ldexp.c b/newlib/libm/mathfp/s_ldexp.c new file mode 100644 index 0000000..f68e8e4 --- /dev/null +++ b/newlib/libm/mathfp/s_ldexp.c @@ -0,0 +1,123 @@ + +/* @(#)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 +@ifinfo +<[val]> times 2 to the power <[exp]>. +@end ifinfo +@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 +<<ldexp>> is ANSI, <<ldexpf>> is an extension. + +*/ + +/****************************************************************** + * 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 + +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 + 1023)) + { + errno = ERANGE; + d = z_infinity.d; + } + else if (exp < DBL_MIN_EXP) + { + errno = ERANGE; + d = -z_infinity.d; + } + else + { + hd &= 0x800fffff; + hd |= exp << 20; + SET_HIGH_WORD (d, hd); + } + } + + return (d); +} + +#endif /* _DOUBLE_IS_32BITS */ |