ticossin.c - plan9port - [fork] Plan 9 from user space
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---
ticossin.c (2117B)
---
1 #include <u.h>
2 #include <libc.h>
3 #include <draw.h>
4
5 /*
6 * 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 */
19 160, /* 9 */
20 178, /* 10 */
21 195, /* 11 */
22 213, /* 12 */
23 230, /* 13 */
24 248, /* 14 */
25 265, /* 15 */
26 282, /* 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 */
42 543, /* 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 */
55 724, /* 45 */
56 737, /* 46 */
57 749, /* 47 */
58 761, /* 48 */
59 773, /* 49 */
60 784, /* 50 */
61 796, /* 51 */
62 807, /* 52 */
63 818, /* 53 */
64 828, /* 54 */
65 839, /* 55 */
66 849, /* 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 */
75 928, /* 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 */
92 1014, /* 82 */
93 1016, /* 83 */
94 1018, /* 84 */
95 1020, /* 85 */
96 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:
118 sinsign = -1;
119 cossign = -1;
120 deg -= 180;
121 /* fall through */
122 case 0:
123 stp = &sinus[deg];
124 ctp = &sinus[90-deg];
125 break;
126 case 3:
127 sinsign = -1;
128 cossign = -1;
129 deg -= 180;
130 /* fall through */
131 case 1:
132 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 }