MATHLIB_exp10_scalar.h

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#ifndef MATHLIB_EXP10_SCALAR_H_
#define MATHLIB_EXP10_SCALAR_H_
 
/******************************************************************************/
/*                                                                            */
/* Includes                                                                   */
/*                                                                            */
/******************************************************************************/
 
#include "../common/MATHLIB_scalarTables.h"
#include "../common/MATHLIB_types.h"
#include "c6x_migration.h"
 
/******************************************************************************/
/*                                                                            */
/* Scalar/C6x implementation of exp                                                  */
/*                                                                            */
/******************************************************************************/
#ifndef __cplusplus /* FOR PROTECTION PURPOSE - C++ NOT SUPPORTED. */
#pragma CODE_SECTION(MATHLIB_exp10_scalar_ci, ".text:optci");
#endif
 
inline float MATHLIB_exp10_scalar_ci(float a)
{
   float        log2_base_x16 = 16.0f * 3.321928095f;
   float        Halfe         = 0.5f;
   float        LnMine        = -87.33654475f;
   float        LnMaxe        = 88.72283905f;
   float        Maxe          = 3.402823466E+38f;
   float        c0            = 0.1667361910f;
   float        c1            = 0.4999999651f;
   float        c2            = 0.9999998881f;
   float        P1            = 0.04331970214844f;
   float        P2            = 1.99663646e-6f;
   float        k10e          = 2.302585093f;
   float        pol, r, r2, r3, res, Ye;
   unsigned int Ttemp, J, K;
   float        Nf;
   int          N;
   double       dT;
 
   Ye = k10e * a;
 
   /* Get N such that |N - x*16/ln(2)| is minimized */
   Nf = (a * log2_base_x16) + Halfe;
   N  = (int) Nf; /* Cast from intermediate variable to appease MISRA */
 
   if ((a * log2_base_x16) < -Halfe) {
      N--;
   }
 
   /* Argument reduction, r, and polynomial approximation pol(r) */
   r  = (Ye - (P1 * (float) N)) - (P2 * (float) N);
   r2 = r * r;
   r3 = r * r2;
 
   pol = (r * c2) + ((r3 * c0) + (r2 * c1));
 
   /* Get index for ktable and jtable */
   K  = _extu((unsigned int) N, 28u, 30u);
   J  = (unsigned int) N & 0x3u;
   dT = MATHLIB_kTable[K] * MATHLIB_jTable[J];
 
   /* Scale exponent to adjust for 2^M */
   Ttemp = _hi(dT) + (((unsigned int) N >> 4) << 20);
   dT    = _itod(Ttemp, _lo(dT));
 
   res = (float) (dT * (1.0 + (double) pol));
 
   /* Early exit for small a */
   if (_extu(_ftoi(Ye), 1u, 24u) < 114u) {
      res = 1.0f + Ye;
   }
 
   /* < LnMin returns 0 */
   if (Ye < LnMine) {
      res = 0.0f;
   }
 
   /* > LnMax returns MAX */
   if (Ye > LnMaxe) {
      res = Maxe;
   }
 
   return (res);
}
 
#endif // MATHLIB_EXP10_SCALAR_H_