+++ /dev/null
-
-
-/* @(#)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.
- */
-
-
-static const double one = 1.0;
-
-#define __int32_t long
-#define __uint32_t unsigned long
-#define __IEEE_LITTLE_ENDIAN
-
-#ifdef __IEEE_BIG_ENDIAN
-
-typedef union
-{
- struct
- {
- __uint32_t msw;
- __uint32_t lsw;
- } parts;
- double value;
-} ieee_double_shape_type;
-
-#endif
-
-#ifdef __IEEE_LITTLE_ENDIAN
-
-typedef union
-{
- struct
- {
- __uint32_t lsw;
- __uint32_t msw;
- } parts;
- double value;
-} ieee_double_shape_type;
-
-#endif
-
-
-/* Get two 32 bit ints from a double. */
-
-#define EXTRACT_WORDS(ix0,ix1,d) \
-do { \
- ieee_double_shape_type ew_u; \
- ew_u.value = (d); \
- (ix0) = ew_u.parts.msw; \
- (ix1) = ew_u.parts.lsw; \
-} while (0)
-
-/* Get the more significant 32 bit int from a double. */
-
-#define GET_HIGH_WORD(i,d) \
-do { \
- ieee_double_shape_type gh_u; \
- gh_u.value = (d); \
- (i) = gh_u.parts.msw; \
-} while (0)
-
-/* Get the less significant 32 bit int from a double. */
-
-#define GET_LOW_WORD(i,d) \
-do { \
- ieee_double_shape_type gl_u; \
- gl_u.value = (d); \
- (i) = gl_u.parts.lsw; \
-} while (0)
-
-/* Set a double from two 32 bit ints. */
-
-#define INSERT_WORDS(d,ix0,ix1) \
-do { \
- ieee_double_shape_type iw_u; \
- iw_u.parts.msw = (ix0); \
- iw_u.parts.lsw = (ix1); \
- (d) = iw_u.value; \
-} while (0)
-
-
-
-
-double modf(double x, double *iptr)
-{
- __int32_t i0,i1,j_0;
- __uint32_t i;
- EXTRACT_WORDS(i0,i1,x);
- j_0 = ((i0>>20)&0x7ff)-0x3ff; /* exponent of x */
- if(j_0<20) { /* integer part in high x */
- if(j_0<0) { /* |x|<1 */
- INSERT_WORDS(*iptr,i0&0x80000000U,0); /* *iptr = +-0 */
- return x;
- } else {
- i = (0x000fffff)>>j_0;
- if(((i0&i)|i1)==0) { /* x is integral */
- __uint32_t high;
- *iptr = x;
- GET_HIGH_WORD(high,x);
- INSERT_WORDS(x,high&0x80000000U,0); /* return +-0 */
- return x;
- } else {
- INSERT_WORDS(*iptr,i0&(~i),0);
- return x - *iptr;
- }
- }
- } else if (j_0>51) { /* no fraction part */
- __uint32_t high;
- *iptr = x*one;
- GET_HIGH_WORD(high,x);
- INSERT_WORDS(x,high&0x80000000U,0); /* return +-0 */
- return x;
- } else { /* fraction part in low x */
- i = ((__uint32_t)(0xffffffffU))>>(j_0-20);
- if((i1&i)==0) { /* x is integral */
- __uint32_t high;
- *iptr = x;
- GET_HIGH_WORD(high,x);
- INSERT_WORDS(x,high&0x80000000U,0); /* return +-0 */
- return x;
- } else {
- INSERT_WORDS(*iptr,i0,i1&(~i));
- return x - *iptr;
- }
- }
-}
-
-//#endif /* _DOUBLE_IS_32BITS */
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