/* $OpenBSD: modf.c,v 1.1 2005/04/01 10:54:27 mickey 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 1.1 2005/04/01 10:54:27 mickey 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 #include /* 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_ */ #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; 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; } } }