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authorArend van Spriel <arend@broadcom.com>2011-05-31 13:22:16 +0400
committerJohn W. Linville <linville@tuxdriver.com>2011-06-03 23:01:07 +0400
commit10f8113ecb76eea72f96c7cfb72d7fed7c282565 (patch)
tree85dd734aeee52e3f21851f11436f4dabaf130033 /include/linux/cordic.h
parent7150962d637cf38617924f7f72ea00612283eb89 (diff)
downloadlinux-10f8113ecb76eea72f96c7cfb72d7fed7c282565.tar.xz
lib: cordic: add library module providing cordic angle calculation
The brcm80211 driver in the staging tree has a cordic function to determine cosine and sine for a given angle. Feedback received from John Linville suggested that these kind of functions should be made available to others as a library function in the kernel tree. The b43 driver also has a cordic angle calculation implemented. Cc: linux-kernel@vger.kernel.org Cc: linux-wireless@vger.kernel.org Cc: "John W. Linville" <linville@tuxdriver.com> Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Dan Carpenter <error27@gmail.com> Cc: Randy Dunlap <rdunlap@xenotime.net> Cc: Larry Finger <Larry.Finger@lwfinger.net> Reviewed-by: Roland Vossen <rvossen@broadcom.com> Reviewed-by: Henry Ptasinski <henryp@broadcom.com> Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com> Signed-off-by: Arend van Spriel <arend@broadcom.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'include/linux/cordic.h')
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diff --git a/include/linux/cordic.h b/include/linux/cordic.h
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+/*
+ * 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.
+ */
+#ifndef __CORDIC_H_
+#define __CORDIC_H_
+
+#include <linux/types.h>
+
+/**
+ * struct cordic_iq - i/q coordinate.
+ *
+ * @i: real part of coordinate (in phase).
+ * @q: imaginary part of coordinate (quadrature).
+ */
+struct cordic_iq {
+ s32 i;
+ s32 q;
+};
+
+/**
+ * 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.
+ *
+ * The function calculates the i/q coordinate for a given angle using
+ * cordic algorithm. The coordinate consists of a real (i) and an
+ * imaginary (q) part. The real part is essentially the cosine of the
+ * angle and the imaginary part is the sine of the angle. The returned
+ * values are scaled by 2^16 for precision. The range for theta is
+ * for -180 degrees to +180 degrees. Passed values outside this range are
+ * converted before doing the actual calculation.
+ */
+struct cordic_iq cordic_calc_iq(s32 theta);
+
+#endif /* __CORDIC_H_ */