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/* $OpenBSD: modf.c,v 1.4 2002/02/19 19:39:36 millert Exp $ */
/* @(#)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.
* ====================================================
*/
#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$OpenBSD: modf.c,v 1.4 2002/02/19 19:39:36 millert Exp $";
#endif
/*
* 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 "math.h"
/*
* ====================================================
* 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.
* ====================================================
*/
/*
* from: @(#)fdlibm.h 5.1 93/09/24
*/
#ifndef _MATH_PRIVATE_H_
#define _MATH_PRIVATE_H_
#include <sys/types.h>
#include <machine/endian.h>
/* The original fdlibm code used statements like:
n0 = ((*(int*)&one)>>29)^1; * index of high word *
ix0 = *(n0+(int*)&x); * high word of x *
ix1 = *((1-n0)+(int*)&x); * low word of x *
to dig two 32 bit words out of the 64 bit IEEE floating point
value. That is non-ANSI, and, moreover, the gcc instruction
scheduler gets it wrong. We instead use the following macros.
Unlike the original code, we determine the endianness at compile
time, not at run time; I don't see much benefit to selecting
endianness at run time. */
/* A union which permits us to convert between a double and two 32 bit
ints. */
/*
* The arm32 port is little endian except for the FP word order which is
* big endian.
*/
#if (BYTE_ORDER == BIG_ENDIAN) || defined(arm32)
typedef union
{
double value;
struct
{
u_int32_t msw;
u_int32_t lsw;
} parts;
} ieee_double_shape_type;
#endif
#if (BYTE_ORDER == LITTLE_ENDIAN) && !defined(arm32)
typedef union
{
double value;
struct
{
u_int32_t lsw;
u_int32_t msw;
} parts;
} 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)
/* Set the more significant 32 bits of a double from an int. */
#define SET_HIGH_WORD(d,v) \
do { \
ieee_double_shape_type sh_u; \
sh_u.value = (d); \
sh_u.parts.msw = (v); \
(d) = sh_u.value; \
} while (0)
/* Set the less significant 32 bits of a double from an int. */
#define SET_LOW_WORD(d,v) \
do { \
ieee_double_shape_type sl_u; \
sl_u.value = (d); \
sl_u.parts.lsw = (v); \
(d) = sl_u.value; \
} while (0)
/* A union which permits us to convert between a float and a 32 bit
int. */
typedef union
{
float value;
u_int32_t word;
} ieee_float_shape_type;
/* Get a 32 bit int from a float. */
#define GET_FLOAT_WORD(i,d) \
do { \
ieee_float_shape_type gf_u; \
gf_u.value = (d); \
(i) = gf_u.word; \
} while (0)
/* Set a float from a 32 bit int. */
#define SET_FLOAT_WORD(d,i) \
do { \
ieee_float_shape_type sf_u; \
sf_u.word = (i); \
(d) = sf_u.value; \
} while (0)
/* ieee style elementary functions */
extern double __ieee754_sqrt(double);
extern double __ieee754_acos(double);
extern double __ieee754_acosh(double);
extern double __ieee754_log(double);
extern double __ieee754_atanh(double);
extern double __ieee754_asin(double);
extern double __ieee754_atan2(double,double);
extern double __ieee754_exp(double);
extern double __ieee754_cosh(double);
extern double __ieee754_fmod(double,double);
extern double __ieee754_pow(double,double);
extern double __ieee754_lgamma_r(double,int *);
extern double __ieee754_gamma_r(double,int *);
extern double __ieee754_lgamma(double);
extern double __ieee754_gamma(double);
extern double __ieee754_log10(double);
extern double __ieee754_sinh(double);
extern double __ieee754_hypot(double,double);
extern double __ieee754_j0(double);
extern double __ieee754_j1(double);
extern double __ieee754_y0(double);
extern double __ieee754_y1(double);
extern double __ieee754_jn(int,double);
extern double __ieee754_yn(int,double);
extern double __ieee754_remainder(double,double);
extern int __ieee754_rem_pio2(double,double*);
extern double __ieee754_scalb(double,double);
/* fdlibm kernel function */
extern double __kernel_standard(double,double,int);
extern double __kernel_sin(double,double,int);
extern double __kernel_cos(double,double);
extern double __kernel_tan(double,double,int);
extern int __kernel_rem_pio2(double*,double*,int,int,int,const int*);
/* ieee style elementary float functions */
extern float __ieee754_sqrtf(float);
extern float __ieee754_acosf(float);
extern float __ieee754_acoshf(float);
extern float __ieee754_logf(float);
extern float __ieee754_atanhf(float);
extern float __ieee754_asinf(float);
extern float __ieee754_atan2f(float,float);
extern float __ieee754_expf(float);
extern float __ieee754_coshf(float);
extern float __ieee754_fmodf(float,float);
extern float __ieee754_powf(float,float);
extern float __ieee754_lgammaf_r(float,int *);
extern float __ieee754_gammaf_r(float,int *);
extern float __ieee754_lgammaf(float);
extern float __ieee754_gammaf(float);
extern float __ieee754_log10f(float);
extern float __ieee754_sinhf(float);
extern float __ieee754_hypotf(float,float);
extern float __ieee754_j0f(float);
extern float __ieee754_j1f(float);
extern float __ieee754_y0f(float);
extern float __ieee754_y1f(float);
extern float __ieee754_jnf(int,float);
extern float __ieee754_ynf(int,float);
extern float __ieee754_remainderf(float,float);
extern int __ieee754_rem_pio2f(float,float*);
extern float __ieee754_scalbf(float,float);
/* float versions of fdlibm kernel functions */
extern float __kernel_sinf(float,float,int);
extern float __kernel_cosf(float,float);
extern float __kernel_tanf(float,float,int);
extern int __kernel_rem_pio2f(float*,float*,int,int,int,const int*);
#endif /* _MATH_PRIVATE_H_ */
static const double one = 1.0;
double
modf(double x, double *iptr)
{
int32_t i0,i1,j0;
u_int32_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 */
u_int32_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 */
u_int32_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 = ((u_int32_t)(0xffffffff))>>(j0-20);
if((i1&i)==0) { /* x is integral */
u_int32_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;
}
}
}
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