;* ======================================================================== *;
;*  TEXAS INSTRUMENTS, INC.                                                 *;
;*                                                                          *;
;*  DSPLIB  DSP Signal Processing Library                                   *;
;*                                                                          *;
;*      Release:        Version 1.02                                        *;
;*      CVS Revision:   1.4     Fri Mar 22 01:51:54 2002 (UTC)              *;
;*      Snapshot date:  18-Apr-2002                                         *;
;*                                                                          *;
;*  This library contains proprietary intellectual property of Texas        *;
;*  Instruments, Inc.  The library and its source code are protected by     *;
;*  various copyrights, and portions may also be protected by patents or    *;
;*  other legal protections.                                                *;
;*                                                                          *;
;*  This software is licensed for use with Texas Instruments TMS320         *;
;*  family DSPs.  This license was provided to you prior to installing      *;
;*  the software.  You may review this license by consulting the file       *;
;*  TI_license.PDF which accompanies the files in this library.             *;
;* ------------------------------------------------------------------------ *;
;*          Copyright (C) 2002 Texas Instruments, Incorporated.             *;
;*                          All Rights Reserved.                            *;
;* ======================================================================== *;
* ========================================================================= *
*   TEXAS INSTRUMENTS, INC.                                                 *
*                                                                           *
*   NAME                                                                    *
*       DSP_fir_r4                                                          *
*                                                                           *
*   REVISION DATE                                                           *
*       25-Feb-2002                                                         *
*                                                                           *
*   USAGE                                                                   *
*       This routine is C-callable and can be called as:                    *
*                                                                           *
*       void DSP_fir_r4                                                     *
*       (                                                                   *
*           const short *x,                                                 *
*           const short *h,                                                 *
*           short       *r,                                                 *
*           int nh,                                                         *
*           int nr                                                          *
*       );                                                                  *
*                                                                           *
*       x[nr+nh-1]: Input samples.                                          *
*       h[nh]     : Filter coefficients. Must be in reverse order.          *
*       r[nr]     : Output samples.                                         *
*       nh        : Number of filter coefficients.                          *
*                   Must be multiple of 4 and >= 8.                         *
*       nr        : Number of output samples.                               *
*                   Must be multiple of 2.                                  *
*                                                                           *
*   DESCRIPTION                                                             *
*       Computes a real FIR filter (direct-form) using coefficients stored  *
*       in vector h.  The real data input is stored in vector x. The        *
*       filter output is stored in vector r. The filter computes nr output  *
*       samples and nh coefficients. It operates on 16-bit data with a      *
*       32-bit accumulate.                                                  *
*                                                                           *
*   C CODE                                                                  *
*       void DSP_fir_r4                                                     *
*       (                                                                   *
*           const short *x,                                                 *
*           const short *h,                                                 *
*           short       *r,                                                 *
*           int nh,                                                         *
*           int nr                                                          *
*       )                                                                   *
*       {                                                                   *
*          int i, j, sum;                                                   *
*                                                                           *
*          for (j = 0; j < nr; j++)                                         *
*          {                                                                *
*             sum = 0;                                                      *
*             for (i = 0; i < nh; i++)                                      *
*               sum += x[i + j] * h[i];                                     *
*             r[j] = sum >> 15;                                             *
*          }                                                                *
*       }                                                                   *
*                                                                           *
*                                                                           *
*   ASSUMPTIONS                                                             *
*       nh must be a multiple of 4 and >= 8.                                *
*       nr must be a multiple of 2 and >= 2.                                *
*                                                                           *
*   MEMORY NOTE                                                             *
*       No memory bank hits under any conditions.                           *
*       This code is Endian neutral.                                        *
*                                                                           *
*   TECHNIQUES                                                              *
*       The assembly routine performs 2 output samples at a time.           *
*       The inner loop is unrolled four times.  The outer loop is unrolled  *
*       twice. Both the inner and outer loops are software pipelined.       *
*                                                                           *
*   CYCLES                                                                  *
*       (8 + nh) * nr/2 + 14                                                *
*                                                                           *
*   CODESIZE                                                                *
*       544 bytes                                                           *
*                                                                           *
*                                                                           *
* ------------------------------------------------------------------------- *
*             Copyright (c) 2002 Texas Instruments, Incorporated.           *
*                            All Rights Reserved.                           *
* ========================================================================= *

        .global _DSP_fir_r4

* ========================================================================= *
*   End of file:  dsp_fir_r4.h62                                            *
* ------------------------------------------------------------------------- *
*             Copyright (c) 2002 Texas Instruments, Incorporated.           *
*                            All Rights Reserved.                           *
* ========================================================================= *