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WebSVN – planix.SVN – Blame – /os/branches/feature-vt/sys/src/libdraw/icossin.c – Rev 2

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#include	<u.h>
2 
#include	<libc.h>
3 
#include	<draw.h>
4 
 
5 
/*
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 * Integer sine and cosine for integral degree argument.
7 
 * Tables computed by (sin,cos)(PI*d/180).
8 
 */
9 
static short sinus[91] = {
10 
	0,	/* 0 */
11 
	18,	/* 1 */
12 
	36,	/* 2 */
13 
	54,	/* 3 */
14 
	71,	/* 4 */
15 
	89,	/* 5 */
16 
	107,	/* 6 */
17 
	125,	/* 7 */
18 
	143,	/* 8 */
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	160,	/* 9 */
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	178,	/* 10 */
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	195,	/* 11 */
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	213,	/* 12 */
23 
	230,	/* 13 */
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	248,	/* 14 */
25 
	265,	/* 15 */
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	282,	/* 16 */
27 
	299,	/* 17 */
28 
	316,	/* 18 */
29 
	333,	/* 19 */
30 
	350,	/* 20 */
31 
	367,	/* 21 */
32 
	384,	/* 22 */
33 
	400,	/* 23 */
34 
	416,	/* 24 */
35 
	433,	/* 25 */
36 
	449,	/* 26 */
37 
	465,	/* 27 */
38 
	481,	/* 28 */
39 
	496,	/* 29 */
40 
	512,	/* 30 */
41 
	527,	/* 31 */
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	543,	/* 32 */
43 
	558,	/* 33 */
44 
	573,	/* 34 */
45 
	587,	/* 35 */
46 
	602,	/* 36 */
47 
	616,	/* 37 */
48 
	630,	/* 38 */
49 
	644,	/* 39 */
50 
	658,	/* 40 */
51 
	672,	/* 41 */
52 
	685,	/* 42 */
53 
	698,	/* 43 */
54 
	711,	/* 44 */
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	724,	/* 45 */
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	737,	/* 46 */
57 
	749,	/* 47 */
58 
	761,	/* 48 */
59 
	773,	/* 49 */
60 
	784,	/* 50 */
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	796,	/* 51 */
62 
	807,	/* 52 */
63 
	818,	/* 53 */
64 
	828,	/* 54 */
65 
	839,	/* 55 */
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	849,	/* 56 */
67 
	859,	/* 57 */
68 
	868,	/* 58 */
69 
	878,	/* 59 */
70 
	887,	/* 60 */
71 
	896,	/* 61 */
72 
	904,	/* 62 */
73 
	912,	/* 63 */
74 
	920,	/* 64 */
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	928,	/* 65 */
76 
	935,	/* 66 */
77 
	943,	/* 67 */
78 
	949,	/* 68 */
79 
	956,	/* 69 */
80 
	962,	/* 70 */
81 
	968,	/* 71 */
82 
	974,	/* 72 */
83 
	979,	/* 73 */
84 
	984,	/* 74 */
85 
	989,	/* 75 */
86 
	994,	/* 76 */
87 
	998,	/* 77 */
88 
	1002,	/* 78 */
89 
	1005,	/* 79 */
90 
	1008,	/* 80 */
91 
	1011,	/* 81 */
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	1014,	/* 82 */
93 
	1016,	/* 83 */
94 
	1018,	/* 84 */
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	1020,	/* 85 */
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	1022,	/* 86 */
97 
	1023,	/* 87 */
98 
	1023,	/* 88 */
99 
	1024,	/* 89 */
100 
	1024,	/* 90 */
101 
};
102 
 
103 
void
104 
icossin(int deg, int *cosp, int *sinp)
105 
{
106 
	int sinsign, cossign;
107 
	short *stp, *ctp;
108 
 
109 
	deg %= 360;
110 
	if(deg < 0)
111 
		deg += 360;
112 
	sinsign = 1;
113 
	cossign = 1;
114 
	stp = 0;
115 
	ctp = 0;
116 
	switch(deg/90){
117 
	case 2:
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		sinsign = -1;
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		cossign = -1;
120 
		deg -= 180;
121 
		/* fall through */
122 
	case 0:
123 
		stp = &sinus[deg];
124 
		ctp = &sinus[90-deg];
125 
		break;
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	case 3:
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		sinsign = -1;
128 
		cossign = -1;
129 
		deg -= 180;
130 
		/* fall through */
131 
	case 1:
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		deg = 180-deg;
133 
		cossign = -cossign;
134 
		stp = &sinus[deg];
135 
		ctp = &sinus[90-deg];
136 
		break;
137 
	}
138 
	*sinp = sinsign*stp[0];
139 
	*cosp = cossign*ctp[0];
140 
}