GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libm/src/ld80/e_fmodl.c Lines: 0 55 0.0 %
Date: 2017-11-13 Branches: 0 44 0.0 %

Line Branch Exec Source
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/* @(#)e_fmod.c 1.3 95/01/18 */
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/*-
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 * ====================================================
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 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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 *
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 * Developed at SunSoft, a Sun Microsystems, Inc. business.
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 * Permission to use, copy, modify, and distribute this
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 * software is freely granted, provided that this notice
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 * is preserved.
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 * ====================================================
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 */
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#include <sys/types.h>
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#include <machine/ieee.h>
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#include <float.h>
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#include <math.h>
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#include <stdint.h>
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#include "math_private.h"
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#define	BIAS (LDBL_MAX_EXP - 1)
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/*
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 * These macros add and remove an explicit integer bit in front of the
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 * fractional mantissa, if the architecture doesn't have such a bit by
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 * default already.
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 */
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#ifdef LDBL_IMPLICIT_NBIT
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#define	LDBL_NBIT	0
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#define	SET_NBIT(hx)	((hx) | (1ULL << LDBL_MANH_SIZE))
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#define	HFRAC_BITS	EXT_FRACHBITS
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#else
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#define	LDBL_NBIT	0x80000000
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#define	SET_NBIT(hx)	(hx)
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#define	HFRAC_BITS	(EXT_FRACHBITS - 1)
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#endif
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#define	MANL_SHIFT	(EXT_FRACLBITS - 1)
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static const long double one = 1.0, Zero[] = {0.0, -0.0,};
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/*
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 * fmodl(x,y)
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 * Return x mod y in exact arithmetic
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 * Method: shift and subtract
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 *
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 * Assumptions:
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 * - The low part of the mantissa fits in a manl_t exactly.
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 * - The high part of the mantissa fits in an int64_t with enough room
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 *   for an explicit integer bit in front of the fractional bits.
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 */
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long double
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fmodl(long double x, long double y)
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{
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	union {
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		long double e;
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		struct ieee_ext bits;
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	} ux, uy;
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	int64_t hx,hz;	/* We need a carry bit even if LDBL_MANH_SIZE is 32. */
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	uint32_t hy;
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	uint32_t lx,ly,lz;
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	int ix,iy,n,sx;
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	ux.e = x;
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	uy.e = y;
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	sx = ux.bits.ext_sign;
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    /* purge off exception values */
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	if((uy.bits.ext_exp|uy.bits.ext_frach|uy.bits.ext_fracl)==0 || /* y=0 */
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	   (ux.bits.ext_exp == BIAS + LDBL_MAX_EXP) ||	 /* or x not finite */
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	   (uy.bits.ext_exp == BIAS + LDBL_MAX_EXP &&
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	    ((uy.bits.ext_frach&~LDBL_NBIT)|uy.bits.ext_fracl)!=0)) /* or y is NaN */
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	    return (x*y)/(x*y);
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	if(ux.bits.ext_exp<=uy.bits.ext_exp) {
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	    if((ux.bits.ext_exp<uy.bits.ext_exp) ||
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	       (ux.bits.ext_frach<=uy.bits.ext_frach &&
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		(ux.bits.ext_frach<uy.bits.ext_frach ||
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		 ux.bits.ext_fracl<uy.bits.ext_fracl))) {
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		return x;		/* |x|<|y| return x or x-y */
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	    }
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	    if(ux.bits.ext_frach==uy.bits.ext_frach &&
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		ux.bits.ext_fracl==uy.bits.ext_fracl) {
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		return Zero[sx];	/* |x|=|y| return x*0*/
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	    }
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	}
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    /* determine ix = ilogb(x) */
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	if(ux.bits.ext_exp == 0) {	/* subnormal x */
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	    ux.e *= 0x1.0p512;
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	    ix = ux.bits.ext_exp - (BIAS + 512);
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	} else {
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	    ix = ux.bits.ext_exp - BIAS;
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	}
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    /* determine iy = ilogb(y) */
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	if(uy.bits.ext_exp == 0) {	/* subnormal y */
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	    uy.e *= 0x1.0p512;
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	    iy = uy.bits.ext_exp - (BIAS + 512);
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	} else {
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	    iy = uy.bits.ext_exp - BIAS;
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	}
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    /* set up {hx,lx}, {hy,ly} and align y to x */
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	hx = SET_NBIT(ux.bits.ext_frach);
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	hy = SET_NBIT(uy.bits.ext_frach);
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	lx = ux.bits.ext_fracl;
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	ly = uy.bits.ext_fracl;
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    /* fix point fmod */
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	n = ix - iy;
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	while(n--) {
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	    hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
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	    if(hz<0){hx = hx+hx+(lx>>MANL_SHIFT); lx = lx+lx;}
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	    else {
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		if ((hz|lz)==0)		/* return sign(x)*0 */
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		    return Zero[sx];
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		hx = hz+hz+(lz>>MANL_SHIFT); lx = lz+lz;
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	    }
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	}
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	hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
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	if(hz>=0) {hx=hz;lx=lz;}
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    /* convert back to floating value and restore the sign */
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	if((hx|lx)==0)			/* return sign(x)*0 */
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	    return Zero[sx];
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	while(hx<(1ULL<<HFRAC_BITS)) {	/* normalize x */
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	    hx = hx+hx+(lx>>MANL_SHIFT); lx = lx+lx;
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	    iy -= 1;
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	}
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	ux.bits.ext_frach = hx; /* The mantissa is truncated here if needed. */
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	ux.bits.ext_fracl = lx;
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	if (iy < LDBL_MIN_EXP) {
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	    ux.bits.ext_exp = iy + (BIAS + 512);
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	    ux.e *= 0x1p-512;
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	} else {
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	    ux.bits.ext_exp = iy + BIAS;
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	}
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	x = ux.e * one;		/* create necessary signal */
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	return x;		/* exact output */
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}