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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [mathfp/] [s_ldexp.c] - Rev 207
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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 @ifnottex <[val]> times 2 to the power <[exp]>. @end ifnottex @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 #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 */