1 /* e_rem_pio2f.c -- float version of e_rem_pio2.c
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 * Debugged and optimized by Bruce D. Evans.
4 */
5
6 /*
7 * ====================================================
8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9 *
10 * Developed at SunPro, a Sun Microsystems, Inc. business.
11 * Permission to use, copy, modify, and distribute this
12 * software is freely granted, provided that this notice
13 * is preserved.
14 * ====================================================
15 */
16
17 #include <sys/cdefs.h>
18 #if 0
19 __FBSDID("$FreeBSD: head/lib/msun/src/e_rem_pio2f.c 336545 2018-07-20 12:42:24Z bde $");
20 #endif
21
22 /* __ieee754_rem_pio2fd(x,y)
23 *
24 * return the remainder of x rem pi/2 in *y
25 * use double precision for everything except passing x
26 * use __kernel_rem_pio2() for large x
27 */
28
29 #include <float.h>
30
31 #include "math.h"
32 #include "math_private.h"
33
34 /*
35 * invpio2: 53 bits of 2/pi
36 * pio2_1: first 25 bits of pi/2
37 * pio2_1t: pi/2 - pio2_1
38 */
39
40 static const double
41 invpio2 = 6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */
42 pio2_1 = 1.57079631090164184570e+00, /* 0x3FF921FB, 0x50000000 */
43 pio2_1t = 1.58932547735281966916e-08; /* 0x3E5110b4, 0x611A6263 */
44
45 #ifdef INLINE_REM_PIO2F
46 static __inline __always_inline
47 #endif
48 int
__ieee754_rem_pio2fd(float x,double * y)49 __ieee754_rem_pio2fd(float x, double *y)
50 {
51 double w,r,fn;
52 double tx[1],ty[1];
53 float z;
54 int32_t e0,n,ix,hx;
55
56 GET_FLOAT_WORD(hx,x);
57 ix = hx&0x7fffffff;
58 /* 33+53 bit pi is good enough for medium size */
59 if(ix<0x4dc90fdb) { /* |x| ~< 2^28*(pi/2), medium size */
60 fn = rnint((float_t)x*invpio2);
61 n = irint(fn);
62 r = x-fn*pio2_1;
63 w = fn*pio2_1t;
64 *y = r-w;
65 return n;
66 }
67 /*
68 * all other (large) arguments
69 */
70 if(ix>=0x7f800000) { /* x is inf or NaN */
71 *y=x-x; return 0;
72 }
73 /* set z = scalbn(|x|,ilogb(|x|)-23) */
74 e0 = (ix>>23)-150; /* e0 = ilogb(|x|)-23; */
75 SET_FLOAT_WORD(z, ix - ((int32_t)(e0<<23)));
76 tx[0] = z;
77 n = __kernel_rem_pio2(tx,ty,e0,1,0);
78 if(hx<0) {*y = -ty[0]; return -n;}
79 *y = ty[0]; return n;
80 }
81