arm_cos_f32.c

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/* ----------------------------------------------------------------------      
* Copyright (C) 2011 ARM Limited. All rights reserved. 
*      
* $Date:        15. December 2011   
* $Revision:    V2.0.0  
*      
* Project:      Cortex-R DSP Library 
* Title:        arm_cos_f32.c      
*      
* Description:  Fast cosine calculation for floating-point values.     
*      
* Target Processor:          Cortex-R4/R5
*
* Version 1.0.0 2011/03/08
*     Alpha release.
*
* Version 1.0.1 2011/09/30
*     Beta release.
*
* Version 2.0.0 2011/12/15
*     Final release. 
* 
* -------------------------------------------------------------------- */     
#include "arm_math.h"     
static const float32_t cosTable[259] = {     
  0.999698817729949950f, 1.000000000000000000f, 0.999698817729949950f,     
  0.998795449733734130f, 0.997290432453155520f, 0.995184719562530520f,     
  0.992479562759399410f, 0.989176511764526370f,     
  0.985277652740478520f, 0.980785250663757320f, 0.975702106952667240f,     
  0.970031261444091800f, 0.963776051998138430f, 0.956940352916717530f,     
  0.949528157711029050f, 0.941544055938720700f,     
  0.932992815971374510f, 0.923879504203796390f, 0.914209783077239990f,     
  0.903989315032958980f, 0.893224298954010010f, 0.881921291351318360f,     
  0.870086967945098880f, 0.857728600502014160f,     
  0.844853579998016360f, 0.831469595432281490f, 0.817584812641143800f,     
  0.803207516670227050f, 0.788346409797668460f, 0.773010432720184330f,     
  0.757208824157714840f, 0.740951120853424070f,     
  0.724247097969055180f, 0.707106769084930420f, 0.689540565013885500f,     
  0.671558976173400880f, 0.653172850608825680f, 0.634393274784088130f,     
  0.615231573581695560f, 0.595699310302734380f,     
  0.575808167457580570f, 0.555570244789123540f, 0.534997642040252690f,     
  0.514102756977081300f, 0.492898195981979370f, 0.471396744251251220f,     
  0.449611335992813110f, 0.427555084228515630f,     
  0.405241310596466060f, 0.382683426141738890f, 0.359895050525665280f,     
  0.336889863014221190f, 0.313681751489639280f, 0.290284663438797000f,     
  0.266712754964828490f, 0.242980182170867920f,     
  0.219101235270500180f, 0.195090323686599730f, 0.170961886644363400f,     
  0.146730467677116390f, 0.122410677373409270f, 0.098017141222953796f,     
  0.073564566671848297f, 0.049067676067352295f,     
  0.024541229009628296f, 0.000000000000000061f, -0.024541229009628296f,     
  -0.049067676067352295f, -0.073564566671848297f, -0.098017141222953796f,     
  -0.122410677373409270f, -0.146730467677116390f,     
  -0.170961886644363400f, -0.195090323686599730f, -0.219101235270500180f,     
  -0.242980182170867920f, -0.266712754964828490f, -0.290284663438797000f,     
  -0.313681751489639280f, -0.336889863014221190f,     
  -0.359895050525665280f, -0.382683426141738890f, -0.405241310596466060f,     
  -0.427555084228515630f, -0.449611335992813110f, -0.471396744251251220f,     
  -0.492898195981979370f, -0.514102756977081300f,     
  -0.534997642040252690f, -0.555570244789123540f, -0.575808167457580570f,     
  -0.595699310302734380f, -0.615231573581695560f, -0.634393274784088130f,     
  -0.653172850608825680f, -0.671558976173400880f,     
  -0.689540565013885500f, -0.707106769084930420f, -0.724247097969055180f,     
  -0.740951120853424070f, -0.757208824157714840f, -0.773010432720184330f,     
  -0.788346409797668460f, -0.803207516670227050f,     
  -0.817584812641143800f, -0.831469595432281490f, -0.844853579998016360f,     
  -0.857728600502014160f, -0.870086967945098880f, -0.881921291351318360f,     
  -0.893224298954010010f, -0.903989315032958980f,     
  -0.914209783077239990f, -0.923879504203796390f, -0.932992815971374510f,     
  -0.941544055938720700f, -0.949528157711029050f, -0.956940352916717530f,     
  -0.963776051998138430f, -0.970031261444091800f,     
  -0.975702106952667240f, -0.980785250663757320f, -0.985277652740478520f,     
  -0.989176511764526370f, -0.992479562759399410f, -0.995184719562530520f,     
  -0.997290432453155520f, -0.998795449733734130f,     
  -0.999698817729949950f, -1.000000000000000000f, -0.999698817729949950f,     
  -0.998795449733734130f, -0.997290432453155520f, -0.995184719562530520f,     
  -0.992479562759399410f, -0.989176511764526370f,     
  -0.985277652740478520f, -0.980785250663757320f, -0.975702106952667240f,     
  -0.970031261444091800f, -0.963776051998138430f, -0.956940352916717530f,     
  -0.949528157711029050f, -0.941544055938720700f,     
  -0.932992815971374510f, -0.923879504203796390f, -0.914209783077239990f,     
  -0.903989315032958980f, -0.893224298954010010f, -0.881921291351318360f,     
  -0.870086967945098880f, -0.857728600502014160f,     
  -0.844853579998016360f, -0.831469595432281490f, -0.817584812641143800f,     
  -0.803207516670227050f, -0.788346409797668460f, -0.773010432720184330f,     
  -0.757208824157714840f, -0.740951120853424070f,     
  -0.724247097969055180f, -0.707106769084930420f, -0.689540565013885500f,     
  -0.671558976173400880f, -0.653172850608825680f, -0.634393274784088130f,     
  -0.615231573581695560f, -0.595699310302734380f,     
  -0.575808167457580570f, -0.555570244789123540f, -0.534997642040252690f,     
  -0.514102756977081300f, -0.492898195981979370f, -0.471396744251251220f,     
  -0.449611335992813110f, -0.427555084228515630f,     
  -0.405241310596466060f, -0.382683426141738890f, -0.359895050525665280f,     
  -0.336889863014221190f, -0.313681751489639280f, -0.290284663438797000f,     
  -0.266712754964828490f, -0.242980182170867920f,     
  -0.219101235270500180f, -0.195090323686599730f, -0.170961886644363400f,     
  -0.146730467677116390f, -0.122410677373409270f, -0.098017141222953796f,     
  -0.073564566671848297f, -0.049067676067352295f,     
  -0.024541229009628296f, -0.000000000000000184f, 0.024541229009628296f,     
  0.049067676067352295f, 0.073564566671848297f, 0.098017141222953796f,     
  0.122410677373409270f, 0.146730467677116390f,     
  0.170961886644363400f, 0.195090323686599730f, 0.219101235270500180f,     
  0.242980182170867920f, 0.266712754964828490f, 0.290284663438797000f,     
  0.313681751489639280f, 0.336889863014221190f,     
  0.359895050525665280f, 0.382683426141738890f, 0.405241310596466060f,     
  0.427555084228515630f, 0.449611335992813110f, 0.471396744251251220f,     
  0.492898195981979370f, 0.514102756977081300f,     
  0.534997642040252690f, 0.555570244789123540f, 0.575808167457580570f,     
  0.595699310302734380f, 0.615231573581695560f, 0.634393274784088130f,     
  0.653172850608825680f, 0.671558976173400880f,     
  0.689540565013885500f, 0.707106769084930420f, 0.724247097969055180f,     
  0.740951120853424070f, 0.757208824157714840f, 0.773010432720184330f,     
  0.788346409797668460f, 0.803207516670227050f,     
  0.817584812641143800f, 0.831469595432281490f, 0.844853579998016360f,     
  0.857728600502014160f, 0.870086967945098880f, 0.881921291351318360f,     
  0.893224298954010010f, 0.903989315032958980f,     
  0.914209783077239990f, 0.923879504203796390f, 0.932992815971374510f,     
  0.941544055938720700f, 0.949528157711029050f, 0.956940352916717530f,     
  0.963776051998138430f, 0.970031261444091800f,     
  0.975702106952667240f, 0.980785250663757320f, 0.985277652740478520f,     
  0.989176511764526370f, 0.992479562759399410f, 0.995184719562530520f,     
  0.997290432453155520f, 0.998795449733734130f,     
  0.999698817729949950f, 1.000000000000000000f, 0.999698817729949950f     
};     
     
float32_t arm_cos_f32(     
  float32_t x)     
{     
  float32_t cosVal, fract, in;     
  uint32_t index;     
  uint32_t tableSize = (uint32_t) TABLE_SIZE;     
  float32_t wa, wb, wc, wd;     
  float32_t a, b, c, d;     
  float32_t *tablePtr;     
  int32_t n;    
  float32_t fractsq, fractby2, fractby6, fractby3, fractsqby2;  
  float32_t oneminusfractby2;  
  float32_t frby2xfrsq, frby6xfrsq;  
  
  /* 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 = n - 1;     
  }     
     
  /* Map input value to [0 1] */     
  in = in - (float32_t) n;     
     
  /* Calculation of index of the table */     
  index = (uint32_t) (tableSize * in);     
     
  /* fractional value calculation */     
  fract = ((float32_t) tableSize * in) - (float32_t) index;     
     
  /* Initialise table pointer */     
  tablePtr = (float32_t *) & cosTable[index];     
     
  /* Read four nearest values of input value from the cos table */     
  a = tablePtr[0];     
  b = tablePtr[1];     
  c = tablePtr[2];     
  d = tablePtr[3];  
  
  /* Cubic interpolation process */     
  fractsq = fract * fract;  
  fractby2 = fract * 0.5f;  
  fractby6 = fract * 0.166666667f;  
  fractby3 = fract * 0.3333333333333f;  
  fractsqby2 = fractsq * 0.5f;  
  frby2xfrsq = (fractby2) * fractsq;  
  frby6xfrsq = (fractby6) * fractsq;  
  oneminusfractby2 = 1.0f - fractby2;  
  wb = fractsqby2 - fractby3;  
  wc = (fractsqby2 + fract);  
  wa = wb - frby6xfrsq;     
  wb = frby2xfrsq - fractsq;  
  cosVal = wa * a;     
  wc = wc - frby2xfrsq;     
  wd = (frby6xfrsq) - fractby6;    
  wb = wb + oneminusfractby2;  
     
  /* Calculate cos value */     
  cosVal = (cosVal + (b * wb)) + ((c * wc) + (d * wd));     
    
  /* Return the output value */     
  return (cosVal);     
     
}