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1 /* origin: FreeBSD /usr/src/lib/msun/src/s_cosf.c */ | 1 /* origin: FreeBSD /usr/src/lib/msun/src/s_cosf.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 c1pio2 = 1 * M_PI_2, /* 0x3FF921FB, 0x54442D18 */ |
21 c1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */ | 21 c2pio2 = 2 * M_PI_2, /* 0x400921FB, 0x54442D18 */ |
22 c2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */ | 22 c3pio2 = 3 * M_PI_2, /* 0x4012D97C, 0x7F3321D2 */ |
23 c3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */ | 23 c4pio2 = 4 * M_PI_2; /* 0x401921FB, 0x54442D18 */ |
24 c4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */ | |
25 | 24 |
26 float cosf(float x) | 25 float cosf(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 */ | 36 /* raise inexact if x != 0 */ |
39 » » » FORCE_EVAL(x + 0x1p120f); | 37 FORCE_EVAL(x + 0x1p120f); |
40 » » » return 1.0f; | 38 return 1.0f; |
41 » » } | 39 } |
42 » » return __cosdf(x); | 40 return __cosdf(x); |
43 » } | 41 } |
44 » if (ix <= 0x407b53d1) { /* |x| ~<= 5*pi/4 */ | 42 if (ix <= 0x407b53d1) { /* |x| ~<= 5*pi/4 */ |
45 » » if (ix > 0x4016cbe3) /* |x| ~> 3*pi/4 */ | 43 if (ix > 0x4016cbe3) /* |x| ~> 3*pi/4 */ |
46 » » » return -__cosdf(sign ? x+c2pio2 : x-c2pio2); | 44 return -__cosdf(sign ? x + c2pio2 : x - c2pio2); |
47 » » else { | 45 else { |
48 » » » if (sign) | 46 if (sign) |
49 » » » » return __sindf(x + c1pio2); | 47 return __sindf(x + c1pio2); |
50 » » » else | 48 else |
51 » » » » return __sindf(c1pio2 - x); | 49 return __sindf(c1pio2 - x); |
52 » » } | 50 } |
53 » } | 51 } |
54 » if (ix <= 0x40e231d5) { /* |x| ~<= 9*pi/4 */ | 52 if (ix <= 0x40e231d5) { /* |x| ~<= 9*pi/4 */ |
55 » » if (ix > 0x40afeddf) /* |x| ~> 7*pi/4 */ | 53 if (ix > 0x40afeddf) /* |x| ~> 7*pi/4 */ |
56 » » » return __cosdf(sign ? x+c4pio2 : x-c4pio2); | 54 return __cosdf(sign ? x + c4pio2 : x - c4pio2); |
57 » » else { | 55 else { |
58 » » » if (sign) | 56 if (sign) |
59 » » » » return __sindf(-x - c3pio2); | 57 return __sindf(-x - c3pio2); |
60 » » » else | 58 else |
61 » » » » return __sindf(x - c3pio2); | 59 return __sindf(x - c3pio2); |
62 » » } | 60 } |
63 » } | 61 } |
64 | 62 |
65 » /* cos(Inf or NaN) is NaN */ | 63 /* cos(Inf or NaN) is NaN */ |
66 » if (ix >= 0x7f800000) | 64 if (ix >= 0x7f800000) |
67 » » return x-x; | 65 return x - x; |
68 | 66 |
69 » /* general argument reduction needed */ | 67 /* general argument reduction needed */ |
70 » n = __rem_pio2f(x,&y); | 68 n = __rem_pio2f(x, &y); |
71 » switch (n&3) { | 69 switch (n & 3) { |
72 » case 0: return __cosdf(y); | 70 case 0: |
73 » case 1: return __sindf(-y); | 71 return __cosdf(y); |
74 » case 2: return -__cosdf(y); | 72 case 1: |
75 » default: | 73 return __sindf(-y); |
76 » » return __sindf(y); | 74 case 2: |
77 » } | 75 return -__cosdf(y); |
| 76 default: |
| 77 return __sindf(y); |
| 78 } |
78 } | 79 } |
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