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-rw-r--r--include/linux/cordic.h48
-rw-r--r--lib/Kconfig7
-rw-r--r--lib/Makefile2
-rw-r--r--lib/cordic.c101
4 files changed, 158 insertions, 0 deletions
diff --git a/include/linux/cordic.h b/include/linux/cordic.h
new file mode 100644
index 00000000000..f932093e20c
--- /dev/null
+++ b/include/linux/cordic.h
@@ -0,0 +1,48 @@
+/*
+ * 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_ */
diff --git a/lib/Kconfig b/lib/Kconfig
index ff9e5a34be7..5c702047c57 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -279,4 +279,11 @@ config AVERAGE
If unsure, say N.
+config CORDIC
+ tristate "Cordic function"
+ help
+ The option provides arithmetic function using cordic algorithm
+ so its calculations are in fixed point. Modules can select this
+ when they require this function. Module will be called cordic.
+
endmenu
diff --git a/lib/Makefile b/lib/Makefile
index 704959d2018..9e3c1b0652d 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -117,6 +117,8 @@ obj-$(CONFIG_AVERAGE) += average.o
obj-$(CONFIG_CPU_RMAP) += cpu_rmap.o
+obj-$(CONFIG_CORDIC) += cordic.o
+
hostprogs-y := gen_crc32table
clean-files := crc32table.h
diff --git a/lib/cordic.c b/lib/cordic.c
new file mode 100644
index 00000000000..aa27a88d7e0
--- /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 functions");
+MODULE_AUTHOR("Broadcom Corporation");
+MODULE_LICENSE("Dual BSD/GPL");