Diff: cmsis_dsp/FastMathFunctions/arm_cos_q15.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/FastMathFunctions/arm_cos_q15.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,205 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010 ARM Limited. All rights reserved.    
+*    
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*    
+* Project:         CMSIS DSP Library    
+* Title:        arm_cos_q15.c    
+*    
+* Description:    Fast cosine calculation for Q15 values.   
+*    
+* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
+*  
+* Version 1.1.0 2012/02/15 
+*    Updated with more optimizations, bug fixes and minor API changes.  
+*   
+* Version 1.0.10 2011/7/15  
+*    Big Endian support added and Merged M0 and M3/M4 Source code.   
+*    
+* Version 1.0.3 2010/11/29   
+*    Re-organized the CMSIS folders and updated documentation.    
+*     
+* Version 1.0.2 2010/11/11    
+*    Documentation updated.     
+*    
+* Version 1.0.1 2010/10/05     
+*    Production release and review comments incorporated.    
+*    
+* Version 1.0.0 2010/09/20     
+*    Production release and review comments incorporated.    
+* -------------------------------------------------------------------- */
+
+#include "arm_math.h"
+
+/**    
+ * @ingroup groupFastMath    
+ */
+
+ /**    
+ * @addtogroup cos    
+ * @{    
+ */
+
+/**   
+* \par    
+* Table Values are in Q15(1.15 Fixed point format) and generation is done in three steps    
+* \par    
+* First Generate cos values in floating point:    
+* tableSize = 256;     
+* <pre>for(n = -1; n < (tableSize + 1); n++)    
+* {    
+*    cosTable[n+1]= cos(2*pi*n/tableSize);    
+* }</pre>   
+* where pi value is  3.14159265358979    
+* \par    
+* Secondly Convert Floating point to Q15(Fixed point):    
+*    (cosTable[i] * pow(2, 15))    
+* \par    
+* Finally Rounding to nearest integer is done    
+*     cosTable[i] += (cosTable[i] > 0 ? 0.5 :-0.5);    
+*/
+
+static const q15_t cosTableQ15[259] = {
+  0x7ff6, 0x7fff, 0x7ff6, 0x7fd9, 0x7fa7, 0x7f62, 0x7f0a, 0x7e9d,
+  0x7e1e, 0x7d8a, 0x7ce4, 0x7c2a, 0x7b5d, 0x7a7d, 0x798a, 0x7885,
+  0x776c, 0x7642, 0x7505, 0x73b6, 0x7255, 0x70e3, 0x6f5f, 0x6dca,
+  0x6c24, 0x6a6e, 0x68a7, 0x66d0, 0x64e9, 0x62f2, 0x60ec, 0x5ed7,
+  0x5cb4, 0x5a82, 0x5843, 0x55f6, 0x539b, 0x5134, 0x4ec0, 0x4c40,
+  0x49b4, 0x471d, 0x447b, 0x41ce, 0x3f17, 0x3c57, 0x398d, 0x36ba,
+  0x33df, 0x30fc, 0x2e11, 0x2b1f, 0x2827, 0x2528, 0x2224, 0x1f1a,
+  0x1c0c, 0x18f9, 0x15e2, 0x12c8, 0xfab, 0xc8c, 0x96b, 0x648,
+  0x324, 0x0, 0xfcdc, 0xf9b8, 0xf695, 0xf374, 0xf055, 0xed38,
+  0xea1e, 0xe707, 0xe3f4, 0xe0e6, 0xdddc, 0xdad8, 0xd7d9, 0xd4e1,
+  0xd1ef, 0xcf04, 0xcc21, 0xc946, 0xc673, 0xc3a9, 0xc0e9, 0xbe32,
+  0xbb85, 0xb8e3, 0xb64c, 0xb3c0, 0xb140, 0xaecc, 0xac65, 0xaa0a,
+  0xa7bd, 0xa57e, 0xa34c, 0xa129, 0x9f14, 0x9d0e, 0x9b17, 0x9930,
+  0x9759, 0x9592, 0x93dc, 0x9236, 0x90a1, 0x8f1d, 0x8dab, 0x8c4a,
+  0x8afb, 0x89be, 0x8894, 0x877b, 0x8676, 0x8583, 0x84a3, 0x83d6,
+  0x831c, 0x8276, 0x81e2, 0x8163, 0x80f6, 0x809e, 0x8059, 0x8027,
+  0x800a, 0x8000, 0x800a, 0x8027, 0x8059, 0x809e, 0x80f6, 0x8163,
+  0x81e2, 0x8276, 0x831c, 0x83d6, 0x84a3, 0x8583, 0x8676, 0x877b,
+  0x8894, 0x89be, 0x8afb, 0x8c4a, 0x8dab, 0x8f1d, 0x90a1, 0x9236,
+  0x93dc, 0x9592, 0x9759, 0x9930, 0x9b17, 0x9d0e, 0x9f14, 0xa129,
+  0xa34c, 0xa57e, 0xa7bd, 0xaa0a, 0xac65, 0xaecc, 0xb140, 0xb3c0,
+  0xb64c, 0xb8e3, 0xbb85, 0xbe32, 0xc0e9, 0xc3a9, 0xc673, 0xc946,
+  0xcc21, 0xcf04, 0xd1ef, 0xd4e1, 0xd7d9, 0xdad8, 0xdddc, 0xe0e6,
+  0xe3f4, 0xe707, 0xea1e, 0xed38, 0xf055, 0xf374, 0xf695, 0xf9b8,
+  0xfcdc, 0x0, 0x324, 0x648, 0x96b, 0xc8c, 0xfab, 0x12c8,
+  0x15e2, 0x18f9, 0x1c0c, 0x1f1a, 0x2224, 0x2528, 0x2827, 0x2b1f,
+  0x2e11, 0x30fc, 0x33df, 0x36ba, 0x398d, 0x3c57, 0x3f17, 0x41ce,
+  0x447b, 0x471d, 0x49b4, 0x4c40, 0x4ec0, 0x5134, 0x539b, 0x55f6,
+  0x5843, 0x5a82, 0x5cb4, 0x5ed7, 0x60ec, 0x62f2, 0x64e9, 0x66d0,
+  0x68a7, 0x6a6e, 0x6c24, 0x6dca, 0x6f5f, 0x70e3, 0x7255, 0x73b6,
+  0x7505, 0x7642, 0x776c, 0x7885, 0x798a, 0x7a7d, 0x7b5d, 0x7c2a,
+  0x7ce4, 0x7d8a, 0x7e1e, 0x7e9d, 0x7f0a, 0x7f62, 0x7fa7, 0x7fd9,
+  0x7ff6, 0x7fff, 0x7ff6
+};
+
+
+/**   
+ * @brief Fast approximation to the trigonometric cosine function for Q15 data.   
+ * @param[in] x Scaled input value in radians.   
+ * @return  cos(x).   
+ *   
+ * The Q15 input value is in the range [0 +0.9999] and is mapped to a radian value in the range [0 2*pi), Here range excludes 2*pi.   
+ */
+
+q15_t arm_cos_q15(
+  q15_t x)
+{
+  q31_t cosVal;                                  /* Temporary variable for output */
+  q15_t *tablePtr;                               /* Pointer to table */
+  q15_t in, in2;                                 /* Temporary variables for input */
+  q31_t wa, wb, wc, wd;                          /* Cubic interpolation coefficients */
+  q15_t a, b, c, d;                              /* Four nearest output values */
+  q15_t fract, fractCube, fractSquare;           /* Variables for fractional value */
+  q15_t oneBy6 = 0x1555;                         /* Fixed point value of 1/6 */
+  q15_t tableSpacing = TABLE_SPACING_Q15;        /* Table spacing */
+  int32_t index;                                 /* Index variable */
+
+  in = x;
+
+  /* Calculate the nearest index */
+  index = (int32_t) in / tableSpacing;
+
+  /* Calculate the nearest value of input */
+  in2 = (q15_t) index *tableSpacing;
+
+  /* Calculation of fractional value */
+  fract = (in - in2) << 8;
+
+  /* fractSquare = fract * fract */
+  fractSquare = (q15_t) ((fract * fract) >> 15);
+
+  /* fractCube = fract * fract * fract */
+  fractCube = (q15_t) ((fractSquare * fract) >> 15);
+
+  /* Checking min and max index of table */
+  if(index < 0)
+  {
+    index = 0;
+  }
+  else if(index > 256)
+  {
+    index = 256;
+  }
+
+  /* Initialise table pointer */
+  tablePtr = (q15_t *) & cosTableQ15[index];
+
+  /* Cubic interpolation process */
+  /* Calculation of wa */
+  /* wa = -(oneBy6)*fractCube + (fractSquare >> 1u) - (0x2AAA)*fract; */
+  wa = (q31_t) oneBy6 *fractCube;
+  wa += (q31_t) 0x2AAA *fract;
+  wa = -(wa >> 15);
+  wa += (fractSquare >> 1u);
+
+  /* Read first nearest value of output from the cos table */
+  a = *tablePtr++;
+
+  /* cosVal = a * wa */
+  cosVal = a * wa;
+
+  /* Calculation of wb */
+  wb = (((fractCube >> 1u) - fractSquare) - (fract >> 1u)) + 0x7FFF;
+
+  /* Read second nearest value of output from the cos table */
+  b = *tablePtr++;
+
+  /*      cosVal += b*wb */
+  cosVal += b * wb;
+
+  /* Calculation of wc */
+  wc = -(q31_t) fractCube + fractSquare;
+  wc = (wc >> 1u) + fract;
+
+  /* Read third nearest value of output from the cos table */
+  c = *tablePtr++;
+
+  /* cosVal += c*wc */
+  cosVal += c * wc;
+
+  /* Calculation of wd */
+  /* wd = (oneBy6)*fractCube - (oneBy6)*fract; */
+  fractCube = fractCube - fract;
+  wd = ((q15_t) (((q31_t) oneBy6 * fractCube) >> 15));
+
+  /* Read fourth nearest value of output from the cos table */
+  d = *tablePtr++;
+
+  /* cosVal += d*wd; */
+  cosVal += d * wd;
+
+  /* Convert output value in 1.15(q15) format and saturate */
+  cosVal = __SSAT((cosVal >> 15), 16);
+
+  /* Return the output value in 1.15(q15) format */
+  return ((q15_t) cosVal);
+
+}
+
+/**    
+ * @} end of cos group    
+ */