Diff: FastMathFunctions/arm_sin_f32.c

Revision:

0:3d9c67d97d6f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FastMathFunctions/arm_sin_f32.c	Mon Jul 28 15:03:15 2014 +0000
@@ -0,0 +1,139 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
+*    
+* $Date:        12. March 2014
+* $Revision: 	V1.4.3
+*    
+* Project: 	    CMSIS DSP Library    
+* Title:		arm_sin_f32.c    
+*    
+* Description:	Fast sine calculation for floating-point values.   
+*    
+* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
+*  
+* Redistribution and use in source and binary forms, with or without 
+* modification, are permitted provided that the following conditions
+* are met:
+*   - Redistributions of source code must retain the above copyright
+*     notice, this list of conditions and the following disclaimer.
+*   - Redistributions in binary form must reproduce the above copyright
+*     notice, this list of conditions and the following disclaimer in
+*     the documentation and/or other materials provided with the 
+*     distribution.
+*   - Neither the name of ARM LIMITED nor the names of its contributors
+*     may be used to endorse or promote products derived from this
+*     software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
+* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+* POSSIBILITY OF SUCH DAMAGE. 
+* -------------------------------------------------------------------- */
+
+#include "arm_math.h"
+#include "arm_common_tables.h"
+
+/**    
+ * @ingroup groupFastMath    
+ */
+
+/**    
+ * @defgroup sin Sine    
+ *    
+ * Computes the trigonometric sine function using a combination of table lookup   
+ * and cubic interpolation.  There are separate functions for   
+ * Q15, Q31, and floating-point data types.   
+ * The input to the floating-point version is in radians while the   
+ * fixed-point Q15 and Q31 have a scaled input with the range   
+ * [0 +0.9999] mapping to [0 2*pi).  The fixed-point range is chosen so that a
+ * value of 2*pi wraps around to 0.
+ *   
+ * The implementation is based on table lookup using 256 values together with cubic interpolation.   
+ * The steps used are:   
+ *  -# Calculation of the nearest integer table index   
+ *  -# Fetch the four table values a, b, c, and d     
+ *  -# Compute the fractional portion (fract) of the table index.   
+ *  -# Calculation of wa, wb, wc, wd    
+ *  -# The final result equals <code>a*wa + b*wb + c*wc + d*wd</code>   
+ *   
+ * where   
+ * <pre>    
+ *    a=Table[index-1];    
+ *    b=Table[index+0];    
+ *    c=Table[index+1];    
+ *    d=Table[index+2];    
+ * </pre>   
+ * and   
+ * <pre>    
+ *    wa=-(1/6)*fract.^3 + (1/2)*fract.^2 - (1/3)*fract;    
+ *    wb=(1/2)*fract.^3 - fract.^2 - (1/2)*fract + 1;    
+ *    wc=-(1/2)*fract.^3+(1/2)*fract.^2+fract;    
+ *    wd=(1/6)*fract.^3 - (1/6)*fract;    
+ * </pre>    
+ */
+
+/**    
+ * @addtogroup sin    
+ * @{    
+ */
+
+/**   
+ * @brief  Fast approximation to the trigonometric sine function for floating-point data.   
+ * @param[in] x input value in radians.   
+ * @return  sin(x).   
+ */
+
+float32_t arm_sin_f32(
+  float32_t x)
+{
+  float32_t sinVal, fract, in;                           /* Temporary variables for input, output */
+  uint16_t index;                                        /* Index variable */
+  float32_t a, b;                                        /* Two nearest output values */
+  int32_t n;
+  float32_t findex;
+
+  /* input x is in radians */
+  /* Scale the input to [0 1] range from [0 2*PI] , divide input by 2*pi */
+  in = x * 0.159154943092f;
+
+  /* Calculation of floor value of input */
+  n = (int32_t) in;
+
+  /* Make negative values towards -infinity */
+  if(x < 0.0f)
+  {
+    n--;
+  }
+
+  /* Map input value to [0 1] */
+  in = in - (float32_t) n;
+
+  /* Calculation of index of the table */
+  findex = (float32_t) FAST_MATH_TABLE_SIZE * in;
+  index = ((uint16_t)findex) & 0x1ff;
+
+  /* fractional value calculation */
+  fract = findex - (float32_t) index;
+
+  /* Read two nearest values of input value from the sin table */
+  a = sinTable_f32[index];
+  b = sinTable_f32[index+1];
+
+  /* Linear interpolation process */
+  sinVal = (1.0f-fract)*a + fract*b;
+
+  /* Return the output value */
+  return (sinVal);
+}
+
+/**    
+ * @} end of sin group    
+ */