Math: Update comments for CORDIC trig functions

The SOF code documentation syntax comments are added to header
trig.h. Some comments in trig.c are trimmed due to placing
more detailed documentation into the header.

Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>

Author: singalsu

src/include/sof/math/trig.h

@@ -39,14 +39,49 @@ struct cordic_cmpx {
 	int32_t im;
 };
 
+/**
+ * cordic_approx() - CORDIC-based approximation of sine and cosine
+ * @th_rad_fxp: Input angle in radian Q4.28 format
+ * @a_idx: Used LUT size
+ * @sign: Output pointer to sine/cosine sign
+ * @b_yn: Output pointer to sine value in Q2.30 format
+ * @xn: Output pointer to cosine value in Q2.30 format
+ * @th_cdc_fxp: Output pointer to the residual angle in Q2.30 format
+ */
 void cordic_approx(int32_t th_rad_fxp, int32_t a_idx, int32_t *sign, int32_t *b_yn, int32_t *xn,
 		   int32_t *th_cdc_fxp);
+
+/**
+ * is_scalar_cordic_acos() - CORDIC-based approximation for inverse cosine
+ * @realvalue: Input cosine value in Q2.30 format
+ * @numiters_minus_one: Number of iterations minus one
+ * Return: Inverse cosine angle in Q3.29 format
+ */
 int32_t is_scalar_cordic_acos(int32_t realvalue, int numiters_minus_one);
+
+/**
+ * is_scalar_cordic_asin() - CORDIC-based approximation for inverse sine
+ * @realvalue: Input sine value in Q2.30 format
+ * @numiters_minus_one: Number of iterations minus one
+ * Return: Inverse sine angle in Q2.30 format
+ */
 int32_t is_scalar_cordic_asin(int32_t realvalue, int numiters_minus_one);
 
+/**
+ * cmpx_cexp() - CORDIC-based approximation of complex exponential e^(j*THETA)
+ * @sign: Sine sign
+ * @b_yn: Sine value in Q2.30 format
+ * @xn: Cosine value in Q2.30 format
+ * @type: CORDIC type
+ * @cexp: Output pointer to complex result in struct cordic_cmpx
+ */
 void cmpx_cexp(int32_t sign, int32_t b_yn, int32_t xn, cordic_cfg type, struct cordic_cmpx *cexp);
-/* Input is Q4.28, output is Q1.31 */
+
 /**
+ * sin_fixed_32b() - Sine function using CORDIC algorithm
+ * @th_rad_fxp: Input angle in radian Q4.28 format
+ * Return: Sine value in Q1.31 format
+ *
  * Compute fixed point cordicsine with table lookup and interpolation
  * The cordic sine algorithm converges, when the angle is in the range
  * [-pi/2, pi/2).If an angle is outside of this range, then a multiple of
@@ -75,6 +110,10 @@ static inline int32_t sin_fixed_32b(int32_t th_rad_fxp)
 }
 
 /**
+ * cos_fixed_32b() - Cosine function using CORDIC algorithm
+ * @th_rad_fxp: Input angle in radian Q4.28 format
+ * Return: Cosine value in Q1.31 format
+ *
  * Compute fixed point cordicsine with table lookup and interpolation
  * The cordic cosine algorithm converges, when the angle is in the range
  * [-pi/2, pi/2).If an angle is outside of this range, then a multiple of
@@ -102,8 +141,11 @@ static inline int32_t cos_fixed_32b(int32_t th_rad_fxp)
 	return sat_int32(Q_SHIFT_LEFT((int64_t)th_cdc_fxp, 30, 31));
 }
 
-/* Input is Q4.28, output is Q1.15 */
 /**
+ * sin_fixed_16b() - Sine function using CORDIC algorithm
+ * @th_rad_fxp: Input angle in radian Q4.28 format
+ * Return: Sine value in Q1.15 format
+ *
  * Compute fixed point cordic sine with table lookup and interpolation
  * The cordic sine algorithm converges, when the angle is in the range
  * [-pi/2, pi/2).If an angle is outside of this range, then a multiple of
@@ -133,6 +175,10 @@ static inline int16_t sin_fixed_16b(int32_t th_rad_fxp)
 }
 
 /**
+ * cos_fixed_16b() - Cosine function using CORDIC algorithm
+ * @th_rad_fxp: Input angle in radian Q4.28 format
+ * Return: Cosine value in Q1.15 format
+ *
  * Compute fixed point cordic cosine with table lookup and interpolation
  * The cordic cos algorithm converges, when the angle is in the range
  * [-pi/2, pi/2).If an angle is outside of this range, then a multiple of
@@ -162,7 +208,10 @@ static inline int16_t cos_fixed_16b(int32_t th_rad_fxp)
 }
 
 /**
- * CORDIC-based approximation of complex exponential e^(j*THETA).
+ * cmpx_exp_32b() - CORDIC-based approximation of complex exponential e^(j*THETA).
+ * @th_rad_fxp: Input angle in radian Q4.28 format
+ * @cexp: Output pointer to complex result in struct cordic_cmpx in Q2.30 format
+ *
  * computes COS(THETA) + j*SIN(THETA) using CORDIC algorithm
  * approximation and returns the complex result.
  * THETA values must be in the range [-2*pi, 2*pi). The cordic
@@ -194,7 +243,10 @@ static inline void cmpx_exp_32b(int32_t th_rad_fxp, struct cordic_cmpx *cexp)
 }
 
 /**
- * CORDIC-based approximation of complex exponential e^(j*THETA).
+ * cmpx_exp_16b() - CORDIC-based approximation of complex exponential e^(j*THETA).
+ * @th_rad_fxp: Input angle in radian Q4.28 format
+ * @cexp: Output pointer to complex result in struct cordic_cmpx in Q1.15 format
+ *
  * computes COS(THETA) + j*SIN(THETA) using CORDIC algorithm
  * approximation and returns the complex result.
  * THETA values must be in the range [-2*pi, 2*pi). The cordic
@@ -227,7 +279,10 @@ static inline void cmpx_exp_16b(int32_t th_rad_fxp, struct cordic_cmpx *cexp)
 }
 
 /**
- * CORDIC-based approximation of inverse sine
+ * asin_fixed_32b() - CORDIC-based approximation of inverse sine
+ * @cdc_asin_th: Input value in Q2.30 format
+ * Return: Inverse sine angle in Q2.30 format
+ *
  * inverse sine of cdc_asin_theta based on a CORDIC approximation.
  * asin(cdc_asin_th) inverse sine angle values in radian produces using the DCORDIC
  * (Double CORDIC) algorithm.
@@ -250,7 +305,10 @@ static inline int32_t asin_fixed_32b(int32_t cdc_asin_th)
 }
 
 /**
- * CORDIC-based approximation of inverse cosine
+ * acos_fixed_32b() - CORDIC-based approximation of inverse cosine
+ * @cdc_acos_th: Input value in Q2.30 format
+ * Return: Inverse cosine angle in Q3.29 format
+ *
  * inverse cosine of cdc_acos_theta based on a CORDIC approximation
  * acos(cdc_acos_th) inverse cosine angle values in radian produces using the DCORDIC
  * (Double CORDIC) algorithm.
@@ -273,7 +331,10 @@ static inline int32_t acos_fixed_32b(int32_t cdc_acos_th)
 }
 
 /**
- * CORDIC-based approximation of inverse sine
+ * asin_fixed_16b() - CORDIC-based approximation of inverse sine
+ * @cdc_asin_th: Input value in Q2.30 format
+ * Return: Inverse sine angle in Q2.14 format
+ *
  * inverse sine of cdc_asin_theta based on a CORDIC approximation.
  * asin(cdc_asin_th) inverse sine angle values in radian produces using the DCORDIC
  * (Double CORDIC) algorithm.
@@ -297,7 +358,10 @@ static inline int16_t asin_fixed_16b(int32_t cdc_asin_th)
 }
 
 /**
- * CORDIC-based approximation of inverse cosine
+ * acos_fixed_16b() - CORDIC-based approximation of inverse cosine
+ * @cdc_acos_th: Input value in Q2.30 format
+ * Return: Inverse cosine angle in Q3.13 format
+ *
  * inverse cosine of cdc_acos_theta based on a CORDIC approximation
  * acos(cdc_acos_th) inverse cosine angle values in radian produces using the DCORDIC
  * (Double CORDIC) algorithm.

src/math/trig.c

@@ -95,9 +95,7 @@ EXPORT_SYMBOL(cordic_approx);
 
 /**
  * CORDIC-based approximation for inverse cosine
- * Arguments	: int32_t cosvalue
- *		  int16_t numiters
- * Return Type	: int32_t
+ * cosvalue is Q2.30, return value is angle in Q3.29 format
  */
 int32_t is_scalar_cordic_acos(int32_t cosvalue, int numiters_minus_one)
 {
@@ -166,9 +164,7 @@ int32_t is_scalar_cordic_acos(int32_t cosvalue, int numiters_minus_one)
 
 /**
  * CORDIC-based approximation for inverse sine
- * Arguments	: int32_t sinvalue
- *		  int16_t numiters
- * Return Type	: int32_t
+ * sinvalue is Q2.30, return value is angle in Q2.30 format
  */
 int32_t is_scalar_cordic_asin(int32_t sinvalue, int numiters_minus_one)
 {
@@ -237,13 +233,9 @@ int32_t is_scalar_cordic_asin(int32_t sinvalue, int numiters_minus_one)
 }
 
 /**
- * approximated complex result
- * Arguments	: int32_t sign
- *		  int32_t b_yn
- *		  int32_t xn
- *		  enum    type
- *		  struct  cordic_cmpx
- * Return Type	: none
+ * cmpx_cexp() - CORDIC-based approximation of complex exponential e^(j*THETA)
+ *
+ * The sine and cosine values are in Q2.30 format from cordic_approx()function.
  */
 void cmpx_cexp(int32_t sign, int32_t b_yn, int32_t xn, cordic_cfg type, struct cordic_cmpx *cexp)
 {