1 /* e_rem_pio2f.c -- float version of e_rem_pio2.c
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, [email protected].
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 /* __ieee754_rem_pio2f(x,y)
18 *
19 * return the remainder of x rem pi/2 in *y
20 * use double precision for everything except passing x
21 * use __kernel_rem_pio2() for large x
22 */
23
24 #include <float.h>
25
26 #include "math.h"
27 #include "math_private.h"
28
29 /*
30 * invpio2: 53 bits of 2/pi
31 * pio2_1: first 25 bits of pi/2
32 * pio2_1t: pi/2 - pio2_1
33 */
34
35 static const double
36 invpio2 = 6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */
37 pio2_1 = 1.57079631090164184570e+00, /* 0x3FF921FB, 0x50000000 */
38 pio2_1t = 1.58932547735281966916e-08; /* 0x3E5110b4, 0x611A6263 */
39
40 #ifdef INLINE_REM_PIO2F
41 static __always_inline
42 #endif
43 int
__ieee754_rem_pio2f(float x,double * y)44 __ieee754_rem_pio2f(float x, double *y)
45 {
46 double w,r,fn;
47 double tx[1],ty[1];
48 float z;
49 int32_t e0,n,ix,hx;
50
51 GET_FLOAT_WORD(hx,x);
52 ix = hx&0x7fffffff;
53 /* 33+53 bit pi is good enough for medium size */
54 if(ix<0x4dc90fdb) { /* |x| ~< 2^28*(pi/2), medium size */
55 fn = rnint((float_t)x*invpio2);
56 n = irint(fn);
57 r = x-fn*pio2_1;
58 w = fn*pio2_1t;
59 *y = r-w;
60 return n;
61 }
62 /*
63 * all other (large) arguments
64 */
65 if(ix>=0x7f800000) { /* x is inf or NaN */
66 *y=x-x; return 0;
67 }
68 /* set z = scalbn(|x|,ilogb(|x|)-23) */
69 e0 = (ix>>23)-150; /* e0 = ilogb(|x|)-23; */
70 SET_FLOAT_WORD(z, ix - ((int32_t)((u_int32_t)e0<<23)));
71 tx[0] = z;
72 n = __kernel_rem_pio2(tx,ty,e0,1,0);
73 if(hx<0) {*y = -ty[0]; return -n;}
74 *y = ty[0]; return n;
75 }
76