1 /* e_fmodl.c -- long double 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 /* remainderq(x,p)
16 * Return :
17 * returns x REM p = x - [x/p]*p as if in infinite
18 * precise arithmetic, where [x/p] is the (infinite bit)
19 * integer nearest x/p (in half way case choose the even one).
20 * Method :
21 * Based on fmodl() return x-[x/p]chopped*p exactlp.
22 */
23
24 #include "quadmath-imp.h"
25
26 static const __float128 zero = 0;
27
28
29 __float128
remainderq(__float128 x,__float128 p)30 remainderq(__float128 x, __float128 p)
31 {
32 int64_t hx,hp;
33 uint64_t sx,lx,lp;
34 __float128 p_half;
35
36 GET_FLT128_WORDS64(hx,lx,x);
37 GET_FLT128_WORDS64(hp,lp,p);
38 sx = hx&0x8000000000000000ULL;
39 hp &= 0x7fffffffffffffffLL;
40 hx &= 0x7fffffffffffffffLL;
41
42 /* purge off exception values */
43 if((hp|lp)==0) return (x*p)/(x*p); /* p = 0 */
44 if((hx>=0x7fff000000000000LL)|| /* x not finite */
45 ((hp>=0x7fff000000000000LL)&& /* p is NaN */
46 (((hp-0x7fff000000000000LL)|lp)!=0)))
47 return (x*p)/(x*p);
48
49
50 if (hp<=0x7ffdffffffffffffLL) x = fmodq(x,p+p); /* now x < 2p */
51 if (((hx-hp)|(lx-lp))==0) return zero*x;
52 x = fabsq(x);
53 p = fabsq(p);
54 if (hp<0x0002000000000000LL) {
55 if(x+x>p) {
56 x-=p;
57 if(x+x>=p) x -= p;
58 }
59 } else {
60 p_half = 0.5Q*p;
61 if(x>p_half) {
62 x-=p;
63 if(x>=p_half) x -= p;
64 }
65 }
66 GET_FLT128_MSW64(hx,x);
67 SET_FLT128_MSW64(x,hx^sx);
68 return x;
69 }
70