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kernel/linux-rt-4.4.41/include/linux/cordic.h 1.75 KB
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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 the
   * 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_ */