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Diffstat (limited to 'newlib/libm/math/s_frexp.c')
| -rw-r--r-- | newlib/libm/math/s_frexp.c | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/newlib/libm/math/s_frexp.c b/newlib/libm/math/s_frexp.c new file mode 100644 index 00000000000..aaa36068ad7 --- /dev/null +++ b/newlib/libm/math/s_frexp.c @@ -0,0 +1,114 @@ + +/* @(#)s_frexp.c 5.1 93/09/24 */ +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunPro, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +/* +FUNCTION + <<frexp>>, <<frexpf>>---split floating-point number +INDEX + frexp +INDEX + frexpf + +ANSI_SYNOPSIS + #include <math.h> + double frexp(double <[val]>, int *<[exp]>); + float frexpf(float <[val]>, int *<[exp]>); + +TRAD_SYNOPSIS + #include <math.h> + double frexp(<[val]>, <[exp]>) + double <[val]>; + int *<[exp]>; + + float frexpf(<[val]>, <[exp]>) + float <[val]>; + int *<[exp]>; + + +DESCRIPTION + All non zero, normal numbers can be described as <[m]> * 2**<[p]>. + <<frexp>> represents the double <[val]> as a mantissa <[m]> + and a power of two <[p]>. The resulting mantissa will always + be greater than or equal to <<0.5>>, and less than <<1.0>> (as + long as <[val]> is nonzero). The power of two will be stored + in <<*>><[exp]>. + +@ifinfo +<[m]> and <[p]> are calculated so that +<[val]> is <[m]> times <<2>> to the power <[p]>. +@end ifinfo +@tex +<[m]> and <[p]> are calculated so that +$ val = m \times 2^p $. +@end tex + +<<frexpf>> is identical, other than taking and returning +floats rather than doubles. + +RETURNS +<<frexp>> returns the mantissa <[m]>. If <[val]> is <<0>>, infinity, +or Nan, <<frexp>> will set <<*>><[exp]> to <<0>> and return <[val]>. + +PORTABILITY +<<frexp>> is ANSI. +<<frexpf>> is an extension. + + +*/ + +/* + * for non-zero x + * x = frexp(arg,&exp); + * return a double fp quantity x such that 0.5 <= |x| <1.0 + * and the corresponding binary exponent "exp". That is + * arg = x*2^exp. + * If arg is inf, 0.0, or NaN, then frexp(arg,&exp) returns arg + * with *exp=0. + */ + +#include "fdlibm.h" + +#ifndef _DOUBLE_IS_32BITS + +#ifdef __STDC__ +static const double +#else +static double +#endif +two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */ + +#ifdef __STDC__ + double frexp(double x, int *eptr) +#else + double frexp(x, eptr) + double x; int *eptr; +#endif +{ + __int32_t hx, ix, lx; + EXTRACT_WORDS(hx,lx,x); + ix = 0x7fffffff&hx; + *eptr = 0; + if(ix>=0x7ff00000||((ix|lx)==0)) return x; /* 0,inf,nan */ + if (ix<0x00100000) { /* subnormal */ + x *= two54; + GET_HIGH_WORD(hx,x); + ix = hx&0x7fffffff; + *eptr = -54; + } + *eptr += (ix>>20)-1022; + hx = (hx&0x800fffff)|0x3fe00000; + SET_HIGH_WORD(x,hx); + return x; +} + +#endif /* _DOUBLE_IS_32BITS */ |