mirror of
https://git.planet-casio.com/Lephenixnoir/OpenLibm.git
synced 2024-12-29 13:03:42 +01:00
142 lines
3.8 KiB
C
142 lines
3.8 KiB
C
/* @(#)e_fmod.c 1.3 95/01/18 */
|
|
/*-
|
|
* ====================================================
|
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
|
*
|
|
* Developed at SunSoft, a Sun Microsystems, Inc. business.
|
|
* Permission to use, copy, modify, and distribute this
|
|
* software is freely granted, provided that this notice
|
|
* is preserved.
|
|
* ====================================================
|
|
*/
|
|
|
|
#include <sys/types.h>
|
|
//#include <machine/ieee.h>
|
|
|
|
#include <float.h>
|
|
#include <openlibm.h>
|
|
#include <stdint.h>
|
|
|
|
#include "math_private.h"
|
|
|
|
#define BIAS (LDBL_MAX_EXP - 1)
|
|
|
|
/*
|
|
* These macros add and remove an explicit integer bit in front of the
|
|
* fractional mantissa, if the architecture doesn't have such a bit by
|
|
* default already.
|
|
*/
|
|
#ifdef LDBL_IMPLICIT_NBIT
|
|
#define LDBL_NBIT 0
|
|
#define SET_NBIT(hx) ((hx) | (1ULL << LDBL_MANH_SIZE))
|
|
#define HFRAC_BITS EXT_FRACHBITS
|
|
#else
|
|
#define LDBL_NBIT 0x80000000
|
|
#define SET_NBIT(hx) (hx)
|
|
#define HFRAC_BITS (EXT_FRACHBITS - 1)
|
|
#endif
|
|
|
|
#define MANL_SHIFT (EXT_FRACLBITS - 1)
|
|
|
|
static const long double one = 1.0, Zero[] = {0.0, -0.0,};
|
|
|
|
/*
|
|
* fmodl(x,y)
|
|
* Return x mod y in exact arithmetic
|
|
* Method: shift and subtract
|
|
*
|
|
* Assumptions:
|
|
* - The low part of the mantissa fits in a manl_t exactly.
|
|
* - The high part of the mantissa fits in an int64_t with enough room
|
|
* for an explicit integer bit in front of the fractional bits.
|
|
*/
|
|
long double
|
|
fmodl(long double x, long double y)
|
|
{
|
|
union {
|
|
long double e;
|
|
struct ieee_ext bits;
|
|
} ux, uy;
|
|
int64_t hx,hz; /* We need a carry bit even if LDBL_MANH_SIZE is 32. */
|
|
uint32_t hy;
|
|
uint32_t lx,ly,lz;
|
|
int ix,iy,n,sx;
|
|
|
|
ux.e = x;
|
|
uy.e = y;
|
|
sx = ux.bits.ext_sign;
|
|
|
|
/* purge off exception values */
|
|
if((uy.bits.ext_exp|uy.bits.ext_frach|uy.bits.ext_fracl)==0 || /* y=0 */
|
|
(ux.bits.ext_exp == BIAS + LDBL_MAX_EXP) || /* or x not finite */
|
|
(uy.bits.ext_exp == BIAS + LDBL_MAX_EXP &&
|
|
((uy.bits.ext_frach&~LDBL_NBIT)|uy.bits.ext_fracl)!=0)) /* or y is NaN */
|
|
return (x*y)/(x*y);
|
|
if(ux.bits.ext_exp<=uy.bits.ext_exp) {
|
|
if((ux.bits.ext_exp<uy.bits.ext_exp) ||
|
|
(ux.bits.ext_frach<=uy.bits.ext_frach &&
|
|
(ux.bits.ext_frach<uy.bits.ext_frach ||
|
|
ux.bits.ext_fracl<uy.bits.ext_fracl))) {
|
|
return x; /* |x|<|y| return x or x-y */
|
|
}
|
|
if(ux.bits.ext_frach==uy.bits.ext_frach &&
|
|
ux.bits.ext_fracl==uy.bits.ext_fracl) {
|
|
return Zero[sx]; /* |x|=|y| return x*0*/
|
|
}
|
|
}
|
|
|
|
/* determine ix = ilogb(x) */
|
|
if(ux.bits.ext_exp == 0) { /* subnormal x */
|
|
ux.e *= 0x1.0p512;
|
|
ix = ux.bits.ext_exp - (BIAS + 512);
|
|
} else {
|
|
ix = ux.bits.ext_exp - BIAS;
|
|
}
|
|
|
|
/* determine iy = ilogb(y) */
|
|
if(uy.bits.ext_exp == 0) { /* subnormal y */
|
|
uy.e *= 0x1.0p512;
|
|
iy = uy.bits.ext_exp - (BIAS + 512);
|
|
} else {
|
|
iy = uy.bits.ext_exp - BIAS;
|
|
}
|
|
|
|
/* set up {hx,lx}, {hy,ly} and align y to x */
|
|
hx = SET_NBIT(ux.bits.ext_frach);
|
|
hy = SET_NBIT(uy.bits.ext_frach);
|
|
lx = ux.bits.ext_fracl;
|
|
ly = uy.bits.ext_fracl;
|
|
|
|
/* fix point fmod */
|
|
n = ix - iy;
|
|
|
|
while(n--) {
|
|
hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
|
|
if(hz<0){hx = hx+hx+(lx>>MANL_SHIFT); lx = lx+lx;}
|
|
else {
|
|
if ((hz|lz)==0) /* return sign(x)*0 */
|
|
return Zero[sx];
|
|
hx = hz+hz+(lz>>MANL_SHIFT); lx = lz+lz;
|
|
}
|
|
}
|
|
hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
|
|
if(hz>=0) {hx=hz;lx=lz;}
|
|
|
|
/* convert back to floating value and restore the sign */
|
|
if((hx|lx)==0) /* return sign(x)*0 */
|
|
return Zero[sx];
|
|
while(hx<(1ULL<<HFRAC_BITS)) { /* normalize x */
|
|
hx = hx+hx+(lx>>MANL_SHIFT); lx = lx+lx;
|
|
iy -= 1;
|
|
}
|
|
ux.bits.ext_frach = hx; /* The mantissa is truncated here if needed. */
|
|
ux.bits.ext_fracl = lx;
|
|
if (iy < LDBL_MIN_EXP) {
|
|
ux.bits.ext_exp = iy + (BIAS + 512);
|
|
ux.e *= 0x1p-512;
|
|
} else {
|
|
ux.bits.ext_exp = iy + BIAS;
|
|
}
|
|
x = ux.e * one; /* create necessary signal */
|
|
return x; /* exact output */
|
|
}
|