ti/dsplib/src/DSP_fir_cplx/c64P/DSP_fir_cplx_cn.c

   1 /* ======================================================================= */
   2 /* DSP_fir_cplx_cn.c -- Complex FIR Filter                                 */
   3 /*                      Natural C Implementation                           */
   4 /*                                                                         */
   5 /* Rev 0.0.1                                                               */
   6 /*                                                                         */
   7 /*  Usage                                                                  */
   8 /*     This routine is C-callable and can be called as:                    */
   9 /*                                                                         */
  10 /*     void DSP_fir_cplx_cn (                                              */
  11 /*         const short *restrict x,                                        */
  12 /*         const short *restrict h,                                        */
  13 /*         short *restrict r,                                              */
  14 /*         int nh,                                                         */
  15 /*         int nr,                                                         */
  16 /*     )                                                                   */
  17 /*                                                                         */
  18 /*     x[2*(nr+nh-1)] : Complex input data. x must point to x[2*(nh-1)].   */
  19 /*     h[2*nh]        : Complex coefficients (in normal order).            */
  20 /*     r[2*nr]        : Complex output data.                               */
  21 /*     nh             : Number of complex coefficients.                    */
  22 /*     nr             : Number of complex output samples.                  */
  23 /*                                                                         */
  24 /*  Description                                                            */
  25 /*      This complex FIR computes nr complex output samples using nh       */
  26 /*      complex coefficients. It operates on 16-bit data with a 32-bit     */
  27 /*      accumulate. Each array consists of an even and odd term with even  */
  28 /*      terms representing the real part of the element and the odd terms  */
  29 /*      the imaginary part. The pointer to input array x must point to the */
  30 /*      (nh)th complex sample, i.e. element 2*(nh-1), upon entry to the    */
  31 /*      function. The coefficients are expected in normal order.           */
  32 /*                                                                         */
  33 /*  Assumptions                                                            */
  34 /*     Arrays x, h, and r do not overlap                                   */
  35 /*                                                                         */
  36 /* Copyright (C) 2011 Texas Instruments Incorporated - http://www.ti.com/  */
  37 /*                                                                         */
  38 /*                                                                         */
  39 /*  Redistribution and use in source and binary forms, with or without     */
  40 /*  modification, are permitted provided that the following conditions     */
  41 /*  are met:                                                               */
  42 /*                                                                         */
  43 /*    Redistributions of source code must retain the above copyright       */
  44 /*    notice, this list of conditions and the following disclaimer.        */
  45 /*                                                                         */
  46 /*    Redistributions in binary form must reproduce the above copyright    */
  47 /*    notice, this list of conditions and the following disclaimer in the  */
  48 /*    documentation and/or other materials provided with the               */
  49 /*    distribution.                                                        */
  50 /*                                                                         */
  51 /*    Neither the name of Texas Instruments Incorporated nor the names of  */
  52 /*    its contributors may be used to endorse or promote products derived  */
  53 /*    from this software without specific prior written permission.        */
  54 /*                                                                         */
  55 /*  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS    */
  56 /*  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT      */
  57 /*  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR  */
  58 /*  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT   */
  59 /*  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,  */
  60 /*  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT       */
  61 /*  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,  */
  62 /*  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY  */
  63 /*  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT    */
  64 /*  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE  */
  65 /*  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.   */
  66 /*                                                                         */
  67 /* ======================================================================= */
  68
  69 #pragma CODE_SECTION(DSP_fir_cplx_cn, ".text:ansi");
  70
  71 #include "DSP_fir_cplx_cn.h"
  72
  73 void DSP_fir_cplx_cn (
  74     const short *restrict x,
  75     const short *restrict h,
  76     short       *restrict r,
  77     int nh,
  78     int nr
  79 )
  80 {
  81     int i, j;
  82     int imag, real;
  83
  84 #ifndef NOASSUME
  85     _nassert((int) nh % 2 == 0);
  86     _nassert((int) nh >= 2);
  87     _nassert((int) nr % 4 == 0);
  88     _nassert((int) nr >= 4);
  89 #endif
  90
  91     for (i = 0; i < 2*nr; i += 2) {
  92         imag = 0;
  93         real = 0;
  94         for (j = 0; j < 2*nh; j += 2) {
  95             real += h[j+0] * x[i-j+0] - h[j+1] * x[i-j+1];
  96             imag += h[j+1] * x[i-j+0] + h[j+0] * x[i-j+1];
  97         }
  98         r[i] = (real >> 15);
  99         r[i+1] = (imag >> 15);
 100     }
 101 }
 102
 103 /* ======================================================================= */
 104 /*  End of file:  DSP_fir_cplx_cn.c                                        */
 105 /* ----------------------------------------------------------------------- */
 106 /*            Copyright (c) 2011 Texas Instruments, Incorporated.          */
 107 /*                           All Rights Reserved.                          */
 108 /* ======================================================================= */
 109