dspf_sp_vecrecip.h

来自「详细的OFDM设计过程」· C头文件 代码 · 共 51 行

/* ======================================================================== */
/*  TEXAS INSTRUMENTS, INC.                                                 */
/*                                                                          */
/*  NAME                                                                    */
/*      DSPF_sp_vecrecip -- Single Precision vector reciprocal              */
/*                                                                          */
/*  USAGE                                                                   */
/*                                                                          */
/*      This routine is C callable, and has the following C prototype:      */
/*                                                                          */
/*      void  DSPF_sp_vecrecip(const float *x,                              */
/*                        float * restrict r,                               */
/*                        int n                                             */
/*                       )                                                  */
/*                                                                          */
/*             x        :  Pointer to input array                           */
/*             r        :  Pointer to output array                          */
/*             n        :  Number of elements in array                      */
/*                                                                          */
/*  DESCRIPTION                                                             */
/*                                                                          */
/*  The DSPF_sp_vecrecip module calculates the reciprocal of each element   */
/*  in the array x and returns the output in array r. It uses 2             */
/*  iterations of the Newton-Raphson method to improve the accuracy         */
/*  of the output generated by the RCPSP instruction of the C67x.           */
/*  Each iteration doubles the accuracy. The initial output generated       */
/*  by RCPSP is 8 bits.So after the first iteration it is 16 bits and       */
/*  after the second it is the full 23 bits. The formula used is:           */
/*                                                                          */
/*               r[n+1] = r[n](2 - v*r[n])                                  */
/*                                                                          */
/*      where v = the number whose reciprocal is to be found.               */
/*      x[0], the seed value for the algorithm, is given by RCPSP.          */
/*                                                                          */
/* ------------------------------------------------------------------------ */
/*            Copyright (c) 2003 Texas Instruments, Incorporated.           */
/*                           All Rights Reserved.                           */
/* ======================================================================== */
#ifndef DSPF_SP_VECRECIP_
#define DSPF_SP_VECRECIP_ 1

void DSPF_sp_vecrecip(const float * x, float * restrict r, int n);

#endif
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/*  End of file: dspf_sp_vecrecip.h                                         */
/* ------------------------------------------------------------------------ */
/*          Copyright (C) 2003 Texas Instruments, Incorporated.             */
/*                          All Rights Reserved.                            */
/* ======================================================================== */