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2 * Copyright (c) 2011 Broadcom Corporation
4 * Permission to use, copy, modify, and/or distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
11 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
13 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
14 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 #include <linux/module.h>
17 #include <linux/cordic.h>
19 #define CORDIC_ANGLE_GEN 39797
20 #define CORDIC_PRECISION_SHIFT 16
21 #define CORDIC_NUM_ITER (CORDIC_PRECISION_SHIFT + 2)
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))
28 static const s32 arctan_table
[] = {
50 * cordic_calc_iq() - calculates the i/q coordinate for given angle
52 * theta: angle in degrees for which i/q coordinate is to be calculated
53 * coord: function output parameter holding the i/q coordinate
55 struct cordic_iq
cordic_calc_iq(s32 theta
)
57 struct cordic_iq coord
;
63 coord
.i
= CORDIC_ANGLE_GEN
;
68 signtheta
= (theta
< 0) ? -1 : 1;
69 theta
= ((theta
+ FIXED(180) * signtheta
) % FIXED(360)) -
70 FIXED(180) * signtheta
;
72 if (FLOAT(theta
) > 90) {
75 } else if (FLOAT(theta
) < -90) {
80 for (iter
= 0; iter
< CORDIC_NUM_ITER
; iter
++) {
82 valtmp
= coord
.i
- (coord
.q
>> iter
);
83 coord
.q
+= (coord
.i
>> iter
);
84 angle
+= arctan_table
[iter
];
86 valtmp
= coord
.i
+ (coord
.q
>> iter
);
87 coord
.q
-= (coord
.i
>> iter
);
88 angle
-= arctan_table
[iter
];
97 EXPORT_SYMBOL(cordic_calc_iq
);
99 MODULE_DESCRIPTION("Cordic functions");
100 MODULE_AUTHOR("Broadcom Corporation");
101 MODULE_LICENSE("Dual BSD/GPL");