Initial import

1 files changed, 101 insertions, 0 deletions

diff --git a/lib/cordic.c b/lib/cordic.c
new file mode 100644
index 000000000..6cf477839
--- /dev/null
+++ b/lib/cordic.c
@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2011 Broadcom Corporation
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+#include <linux/module.h>
+#include <linux/cordic.h>
+
+#define CORDIC_ANGLE_GEN	39797
+#define CORDIC_PRECISION_SHIFT	16
+#define	CORDIC_NUM_ITER		(CORDIC_PRECISION_SHIFT + 2)
+
+#define	FIXED(X)	((s32)((X) << CORDIC_PRECISION_SHIFT))
+#define	FLOAT(X)	(((X) >= 0) \
+		? ((((X) >> (CORDIC_PRECISION_SHIFT - 1)) + 1) >> 1) \
+		: -((((-(X)) >> (CORDIC_PRECISION_SHIFT - 1)) + 1) >> 1))
+
+static const s32 arctan_table[] = {
+	2949120,
+	1740967,
+	919879,
+	466945,
+	234379,
+	117304,
+	58666,
+	29335,
+	14668,
+	7334,
+	3667,
+	1833,
+	917,
+	458,
+	229,
+	115,
+	57,
+	29
+};
+
+/*
+ * cordic_calc_iq() - calculates the i/q coordinate for given angle
+ *
+ * theta: angle in degrees for which i/q coordinate is to be calculated
+ * coord: function output parameter holding the i/q coordinate
+ */
+struct cordic_iq cordic_calc_iq(s32 theta)
+{
+	struct cordic_iq coord;
+	s32 angle, valtmp;
+	unsigned iter;
+	int signx = 1;
+	int signtheta;
+
+	coord.i = CORDIC_ANGLE_GEN;
+	coord.q = 0;
+	angle = 0;
+
+	theta = FIXED(theta);
+	signtheta = (theta < 0) ? -1 : 1;
+	theta = ((theta + FIXED(180) * signtheta) % FIXED(360)) -
+		FIXED(180) * signtheta;
+
+	if (FLOAT(theta) > 90) {
+		theta -= FIXED(180);
+		signx = -1;
+	} else if (FLOAT(theta) < -90) {
+		theta += FIXED(180);
+		signx = -1;
+	}
+
+	for (iter = 0; iter < CORDIC_NUM_ITER; iter++) {
+		if (theta > angle) {
+			valtmp = coord.i - (coord.q >> iter);
+			coord.q += (coord.i >> iter);
+			angle += arctan_table[iter];
+		} else {
+			valtmp = coord.i + (coord.q >> iter);
+			coord.q -= (coord.i >> iter);
+			angle -= arctan_table[iter];
+		}
+		coord.i = valtmp;
+	}
+
+	coord.i *= signx;
+	coord.q *= signx;
+	return coord;
+}
+EXPORT_SYMBOL(cordic_calc_iq);
+
+MODULE_DESCRIPTION("CORDIC algorithm");
+MODULE_AUTHOR("Broadcom Corporation");
+MODULE_LICENSE("Dual BSD/GPL");