1/* fmodq.c -- __float128 version of e_fmod.c.
2 * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
3 */
4/*
5 * ====================================================
6 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
7 *
8 * Developed at SunPro, a Sun Microsystems, Inc. business.
9 * Permission to use, copy, modify, and distribute this
10 * software is freely granted, provided that this notice
11 * is preserved.
12 * ====================================================
13 */
14
15/*
16 * fmodq(x,y)
17 * Return x mod y in exact arithmetic
18 * Method: shift and subtract
19 */
20
21#include "quadmath-imp.h"
22
23static const __float128 one = 1.0, Zero[] = {0.0, -0.0,};
24
25__float128
26fmodq (__float128 x, __float128 y)
27{
28  int64_t n,hx,hy,hz,ix,iy,sx,i;
29  uint64_t lx,ly,lz;
30
31  GET_FLT128_WORDS64(hx,lx,x);
32  GET_FLT128_WORDS64(hy,ly,y);
33  sx = hx&0x8000000000000000ULL;	/* sign of x */
34  hx ^=sx;				/* |x| */
35  hy &= 0x7fffffffffffffffLL;		/* |y| */
36
37  /* purge off exception values */
38  if((hy|ly)==0||(hx>=0x7fff000000000000LL)|| /* y=0,or x not finite */
39    ((hy|((ly|-ly)>>63))>0x7fff000000000000LL))	/* or y is NaN */
40      return (x*y)/(x*y);
41  if(hx<=hy) {
42      if((hx<hy)||(lx<ly)) return x;	/* |x|<|y| return x */
43      if(lx==ly)
44	  return Zero[(uint64_t)sx>>63];	/* |x|=|y| return x*0*/
45  }
46
47  /* determine ix = ilogb(x) */
48  if(hx<0x0001000000000000LL) {	/* subnormal x */
49      if(hx==0) {
50	  for (ix = -16431, i=lx; i>0; i<<=1) ix -=1;
51      } else {
52	  for (ix = -16382, i=hx<<15; i>0; i<<=1) ix -=1;
53      }
54  } else ix = (hx>>48)-0x3fff;
55
56  /* determine iy = ilogb(y) */
57      if(hy<0x0001000000000000LL) {	/* subnormal y */
58	  if(hy==0) {
59	      for (iy = -16431, i=ly; i>0; i<<=1) iy -=1;
60	  } else {
61	      for (iy = -16382, i=hy<<15; i>0; i<<=1) iy -=1;
62	  }
63      } else iy = (hy>>48)-0x3fff;
64
65  /* set up {hx,lx}, {hy,ly} and align y to x */
66      if(ix >= -16382)
67	  hx = 0x0001000000000000LL|(0x0000ffffffffffffLL&hx);
68      else {		/* subnormal x, shift x to normal */
69	  n = -16382-ix;
70	  if(n<=63) {
71	      hx = (hx<<n)|(lx>>(64-n));
72	      lx <<= n;
73	  } else {
74	      hx = lx<<(n-64);
75	      lx = 0;
76	  }
77      }
78      if(iy >= -16382)
79	  hy = 0x0001000000000000LL|(0x0000ffffffffffffLL&hy);
80      else {		/* subnormal y, shift y to normal */
81	  n = -16382-iy;
82	  if(n<=63) {
83	      hy = (hy<<n)|(ly>>(64-n));
84	      ly <<= n;
85	  } else {
86	      hy = ly<<(n-64);
87	      ly = 0;
88	  }
89      }
90
91  /* fix point fmod */
92      n = ix - iy;
93      while(n--) {
94	  hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
95	  if(hz<0){hx = hx+hx+(lx>>63); lx = lx+lx;}
96	  else {
97	      if((hz|lz)==0) 		/* return sign(x)*0 */
98		  return Zero[(uint64_t)sx>>63];
99	      hx = hz+hz+(lz>>63); lx = lz+lz;
100	  }
101      }
102      hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
103      if(hz>=0) {hx=hz;lx=lz;}
104
105  /* convert back to floating value and restore the sign */
106      if((hx|lx)==0) 			/* return sign(x)*0 */
107	  return Zero[(uint64_t)sx>>63];
108      while(hx<0x0001000000000000LL) {	/* normalize x */
109	  hx = hx+hx+(lx>>63); lx = lx+lx;
110	  iy -= 1;
111      }
112      if(iy>= -16382) {	/* normalize output */
113	  hx = ((hx-0x0001000000000000LL)|((iy+16383)<<48));
114	  SET_FLT128_WORDS64(x,hx|sx,lx);
115      } else {		/* subnormal output */
116	  n = -16382 - iy;
117	  if(n<=48) {
118	      lx = (lx>>n)|((uint64_t)hx<<(64-n));
119	      hx >>= n;
120	  } else if (n<=63) {
121	      lx = (hx<<(64-n))|(lx>>n); hx = sx;
122	  } else {
123	      lx = hx>>(n-64); hx = sx;
124	  }
125	  SET_FLT128_WORDS64(x,hx|sx,lx);
126	  x *= one;		/* create necessary signal */
127      }
128      return x;		/* exact output */
129}
130