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1 /* origin: FreeBSD /usr/src/lib/msun/src/s_tanf.c */ | 1 /* origin: FreeBSD /usr/src/lib/msun/src/s_tanf.c */ |
2 /* | 2 /* |
3 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. | 3 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
4 * Optimized by Bruce D. Evans. | 4 * Optimized by Bruce D. Evans. |
5 */ | 5 */ |
6 /* | 6 /* |
7 * ==================================================== | 7 * ==================================================== |
8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. | 8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
9 * | 9 * |
10 * Developed at SunPro, a Sun Microsystems, Inc. business. | 10 * Developed at SunPro, a Sun Microsystems, Inc. business. |
11 * Permission to use, copy, modify, and distribute this | 11 * Permission to use, copy, modify, and distribute this |
12 * software is freely granted, provided that this notice | 12 * software is freely granted, provided that this notice |
13 * is preserved. | 13 * is preserved. |
14 * ==================================================== | 14 * ==================================================== |
15 */ | 15 */ |
16 | 16 |
17 #include "libm.h" | 17 #include "libm.h" |
18 | 18 |
19 /* Small multiples of pi/2 rounded to double precision. */ | 19 /* Small multiples of pi/2 rounded to double precision. */ |
20 static const double | 20 static const double t1pio2 = 1 * M_PI_2, /* 0x3FF921FB, 0x54442D18 */ |
21 t1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */ | 21 t2pio2 = 2 * M_PI_2, /* 0x400921FB, 0x54442D18 */ |
22 t2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */ | 22 t3pio2 = 3 * M_PI_2, /* 0x4012D97C, 0x7F3321D2 */ |
23 t3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */ | 23 t4pio2 = 4 * M_PI_2; /* 0x401921FB, 0x54442D18 */ |
24 t4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */ | |
25 | 24 |
26 float tanf(float x) | 25 float tanf(float x) { |
27 { | 26 double y; |
28 » double y; | 27 uint32_t ix; |
29 » uint32_t ix; | 28 unsigned n, sign; |
30 » unsigned n, sign; | |
31 | 29 |
32 » GET_FLOAT_WORD(ix, x); | 30 GET_FLOAT_WORD(ix, x); |
33 » sign = ix >> 31; | 31 sign = ix >> 31; |
34 » ix &= 0x7fffffff; | 32 ix &= 0x7fffffff; |
35 | 33 |
36 » if (ix <= 0x3f490fda) { /* |x| ~<= pi/4 */ | 34 if (ix <= 0x3f490fda) { /* |x| ~<= pi/4 */ |
37 » » if (ix < 0x39800000) { /* |x| < 2**-12 */ | 35 if (ix < 0x39800000) { /* |x| < 2**-12 */ |
38 » » » /* raise inexact if x!=0 and underflow if subnormal */ | 36 /* raise inexact if x!=0 and underflow if subnormal */ |
39 » » » FORCE_EVAL(ix < 0x00800000 ? x/0x1p120f : x+0x1p120f); | 37 FORCE_EVAL(ix < 0x00800000 ? x / 0x1p120f : x + 0x1p120f); |
40 » » » return x; | 38 return x; |
41 » » } | 39 } |
42 » » return __tandf(x, 0); | 40 return __tandf(x, 0); |
43 » } | 41 } |
44 » if (ix <= 0x407b53d1) { /* |x| ~<= 5*pi/4 */ | 42 if (ix <= 0x407b53d1) { /* |x| ~<= 5*pi/4 */ |
45 » » if (ix <= 0x4016cbe3) /* |x| ~<= 3pi/4 */ | 43 if (ix <= 0x4016cbe3) /* |x| ~<= 3pi/4 */ |
46 » » » return __tandf((sign ? x+t1pio2 : x-t1pio2), 1); | 44 return __tandf((sign ? x + t1pio2 : x - t1pio2), 1); |
47 » » else | 45 else |
48 » » » return __tandf((sign ? x+t2pio2 : x-t2pio2), 0); | 46 return __tandf((sign ? x + t2pio2 : x - t2pio2), 0); |
49 » } | 47 } |
50 » if (ix <= 0x40e231d5) { /* |x| ~<= 9*pi/4 */ | 48 if (ix <= 0x40e231d5) { /* |x| ~<= 9*pi/4 */ |
51 » » if (ix <= 0x40afeddf) /* |x| ~<= 7*pi/4 */ | 49 if (ix <= 0x40afeddf) /* |x| ~<= 7*pi/4 */ |
52 » » » return __tandf((sign ? x+t3pio2 : x-t3pio2), 1); | 50 return __tandf((sign ? x + t3pio2 : x - t3pio2), 1); |
53 » » else | 51 else |
54 » » » return __tandf((sign ? x+t4pio2 : x-t4pio2), 0); | 52 return __tandf((sign ? x + t4pio2 : x - t4pio2), 0); |
55 » } | 53 } |
56 | 54 |
57 » /* tan(Inf or NaN) is NaN */ | 55 /* tan(Inf or NaN) is NaN */ |
58 » if (ix >= 0x7f800000) | 56 if (ix >= 0x7f800000) |
59 » » return x - x; | 57 return x - x; |
60 | 58 |
61 » /* argument reduction */ | 59 /* argument reduction */ |
62 » n = __rem_pio2f(x, &y); | 60 n = __rem_pio2f(x, &y); |
63 » return __tandf(y, n&1); | 61 return __tandf(y, n & 1); |
64 } | 62 } |
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