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16#include <linux/module.h>
17#include <linux/cordic.h>
18
19#define CORDIC_ANGLE_GEN 39797
20#define CORDIC_PRECISION_SHIFT 16
21#define CORDIC_NUM_ITER (CORDIC_PRECISION_SHIFT + 2)
22
23#define FIXED(X) ((s32)((X) << CORDIC_PRECISION_SHIFT))
24#define FLOAT(X) (((X) >= 0) \
25 ? ((((X) >> (CORDIC_PRECISION_SHIFT - 1)) + 1) >> 1) \
26 : -((((-(X)) >> (CORDIC_PRECISION_SHIFT - 1)) + 1) >> 1))
27
28static const s32 arctan_table[] = {
29 2949120,
30 1740967,
31 919879,
32 466945,
33 234379,
34 117304,
35 58666,
36 29335,
37 14668,
38 7334,
39 3667,
40 1833,
41 917,
42 458,
43 229,
44 115,
45 57,
46 29
47};
48
49
50
51
52
53
54
55struct cordic_iq cordic_calc_iq(s32 theta)
56{
57 struct cordic_iq coord;
58 s32 angle, valtmp;
59 unsigned iter;
60 int signx = 1;
61 int signtheta;
62
63 coord.i = CORDIC_ANGLE_GEN;
64 coord.q = 0;
65 angle = 0;
66
67 theta = FIXED(theta);
68 signtheta = (theta < 0) ? -1 : 1;
69 theta = ((theta + FIXED(180) * signtheta) % FIXED(360)) -
70 FIXED(180) * signtheta;
71
72 if (FLOAT(theta) > 90) {
73 theta -= FIXED(180);
74 signx = -1;
75 } else if (FLOAT(theta) < -90) {
76 theta += FIXED(180);
77 signx = -1;
78 }
79
80 for (iter = 0; iter < CORDIC_NUM_ITER; iter++) {
81 if (theta > angle) {
82 valtmp = coord.i - (coord.q >> iter);
83 coord.q += (coord.i >> iter);
84 angle += arctan_table[iter];
85 } else {
86 valtmp = coord.i + (coord.q >> iter);
87 coord.q -= (coord.i >> iter);
88 angle -= arctan_table[iter];
89 }
90 coord.i = valtmp;
91 }
92
93 coord.i *= signx;
94 coord.q *= signx;
95 return coord;
96}
97EXPORT_SYMBOL(cordic_calc_iq);
98
99MODULE_DESCRIPTION("CORDIC algorithm");
100MODULE_AUTHOR("Broadcom Corporation");
101MODULE_LICENSE("Dual BSD/GPL");
102