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