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[/] [openrisc/] [trunk/] [gnu-stable/] [newlib-1.18.0/] [newlib/] [libm/] [common/] [s_modf.c] - Rev 207
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/* @(#)s_modf.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 <<modf>>, <<modff>>---split fractional and integer parts INDEX modf INDEX modff ANSI_SYNOPSIS #include <math.h> double modf(double <[val]>, double *<[ipart]>); float modff(float <[val]>, float *<[ipart]>); TRAD_SYNOPSIS #include <math.h> double modf(<[val]>, <[ipart]>) double <[val]>; double *<[ipart]>; float modff(<[val]>, <[ipart]>) float <[val]>; float *<[ipart]>; DESCRIPTION <<modf>> splits the double <[val]> apart into an integer part and a fractional part, returning the fractional part and storing the integer part in <<*<[ipart]>>>. No rounding whatsoever is done; the sum of the integer and fractional parts is guaranteed to be exactly equal to <[val]>. That is, if <[realpart]> = modf(<[val]>, &<[intpart]>); then `<<<[realpart]>+<[intpart]>>>' is the same as <[val]>. <<modff>> is identical, save that it takes and returns <<float>> rather than <<double>> values. RETURNS The fractional part is returned. Each result has the same sign as the supplied argument <[val]>. PORTABILITY <<modf>> is ANSI C. <<modff>> is an extension. QUICKREF modf ansi pure modff - pure */ /* * modf(double x, double *iptr) * return fraction part of x, and return x's integral part in *iptr. * Method: * Bit twiddling. * * Exception: * No exception. */ #include "fdlibm.h" #ifndef _DOUBLE_IS_32BITS #ifdef __STDC__ static const double one = 1.0; #else static double one = 1.0; #endif #ifdef __STDC__ double modf(double x, double *iptr) #else double modf(x, iptr) double x,*iptr; #endif { __int32_t i0,i1,j0; __uint32_t i; EXTRACT_WORDS(i0,i1,x); j0 = ((i0>>20)&0x7ff)-0x3ff; /* exponent of x */ if(j0<20) { /* integer part in high x */ if(j0<0) { /* |x|<1 */ INSERT_WORDS(*iptr,i0&0x80000000,0); /* *iptr = +-0 */ return x; } else { i = (0x000fffff)>>j0; if(((i0&i)|i1)==0) { /* x is integral */ __uint32_t high; *iptr = x; GET_HIGH_WORD(high,x); INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */ return x; } else { INSERT_WORDS(*iptr,i0&(~i),0); return x - *iptr; } } } else if (j0>51) { /* no fraction part */ __uint32_t high; *iptr = x*one; GET_HIGH_WORD(high,x); INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */ return x; } else { /* fraction part in low x */ i = ((__uint32_t)(0xffffffff))>>(j0-20); if((i1&i)==0) { /* x is integral */ __uint32_t high; *iptr = x; GET_HIGH_WORD(high,x); INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */ return x; } else { INSERT_WORDS(*iptr,i0,i1&(~i)); return x - *iptr; } } } #endif /* _DOUBLE_IS_32BITS */
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