dsp_fir_r4.h64

来自「dm642函数库」· H64 代码 · 共 126 行

;* ======================================================================== *;
;*  TEXAS INSTRUMENTS, INC.                                                 *;
;*                                                                          *;
;*  DSPLIB  DSP Signal Processing Library                                   *;
;*                                                                          *;
;*      Release:        Revision 1.04b                                      *;
;*      CVS Revision:   1.7     Sun Sep 29 03:32:22 2002 (UTC)              *;
;*      Snapshot date:  23-Oct-2003                                         *;
;*                                                                          *;
;*  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) 2003 Texas Instruments, Incorporated.             *;
;*                          All Rights Reserved.                            *;
;* ======================================================================== *;
;* ======================================================================== *;
;*  Assembler compatibility shim for assembling 4.30 and later code on      *;
;*  tools prior to 4.30.                                                    *;
;* ======================================================================== *;
;* ======================================================================== *;
;*  End of assembler compatibility shim.                                    *;
;* ======================================================================== *;
* ========================================================================= *
*   TEXAS INSTRUMENTS, INC.                                                 *
*                                                                           *
*   NAME                                                                    *
*       DSP_fir_r4: FIR Filter (radix 4)                                    *
*                                                                           *
*                                                                           *
*   REVISION DATE                                                           *
*       10-Aug-2001                                                         *
*                                                                           *
*   USAGE                                                                   *
*       This routine is C-callable and can be called as:                    *
*                                                                           *
*       void DSP_fir_r4                                                     *
*       (                                                                   *
*           const short *restrict x,  /* Input array [nr+nh-1 elements] */  *
*           const short *restrict h,  /* Coeff array [nh elements]      */  *
*           short       *restrict r,  /* Output array [nr elements]     */  *
*           int nh,                   /* Number of coefficients.        */  *
*           int nr                    /* Number of output samples.      */  *
*       )                                                                   *
*                                                                           *
*   ARGUMENTS PASSED                                                        *
*       *x    ->      A4                                                    *
*       *h    ->      B4                                                    *
*       *r    ->      A6                                                    *
*       nh    ->      B6                                                    *
*       nr    ->      A8                                                    *
*                                                                           *
*   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 result is stored in vector r.  Input data and     *
*       filter taps are 16-bit, with intermediate values kept at 32-bit     *
*       precision.  Filter taps are expected in Q15 format.                 *
*                                                                           *
*       The following is a natural C implementation with no restrictions.   *
*       This version has restrictions as noted in the ASSUMPTIONS below.    *
*                                                                           *
*       void DSP_fir_r4                                                     *
*       (                                                                   *
*           const short *restrict x,                                        *
*           const short *restrict h,                                        *
*           short       *restrict 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                                                             *
*       Number of taps:    'nh' >= 8, multiple of 4                         *
*       Number of samples: 'nr' >= 4, multiple of 4                         *
*                                                                           *
*   NOTES                                                                   *
*       This function blocks interrupts for its entire duration.  It is     *
*       interrupt tolerant, but not interruptible.                          *
*                                                                           *
*   MEMORY NOTE                                                             *
*       No memory bank hits under any conditions.                           *
*       This code is a LITTLE ENDIAN implementation                         *
*                                                                           *
*   TECHNIQUES                                                              *
*       1.  Load double word instruction is used to simultaneously          *
*           load four values in a single clock cycle.                       *
*       2.  The inner loop is unrolled four times                           *
*                                                                           *
*   CYCLES                                                                  *
*       (8 + nh) * nr/4 + 9                                                 *
*                                                                           *
*       For nh = 12 and nr = 12, cycles = 69                                *
*                                                                           *
*   CODESIZE                                                                *
*       308 bytes.                                                          *
* ------------------------------------------------------------------------- *
*             Copyright (c) 2003 Texas Instruments, Incorporated.           *
*                            All Rights Reserved.                           *
* ========================================================================= *

        .global _DSP_fir_r4

* ========================================================================= *
*   End of file:  dsp_fir_r4.h64                                            *
* ------------------------------------------------------------------------- *
*             Copyright (c) 2003 Texas Instruments, Incorporated.           *
*                            All Rights Reserved.                           *
* ========================================================================= *