dsp_fir_cplx.h64

来自「dm642函数库」· H64 代码 · 共 133 行

;* ======================================================================== *;
;*  TEXAS INSTRUMENTS, INC.                                                 *;
;*                                                                          *;
;*  DSPLIB  DSP Signal Processing Library                                   *;
;*                                                                          *;
;*      Release:        Revision 1.04b                                      *;
;*      CVS Revision:   1.11    Sun Sep 29 03:32:21 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.                                    *;
;* ======================================================================== *;
* ========================================================================= *
*   NAME                                                                    *
*       DSP_fir_cplx -- Hand-Coded Assembly code for                        *
*       Complex Filter.                                                     *
*                                                                           *
*   REVISION DATE                                                           *
*       06-Aug-2001                                                         *
*                                                                           *
*   USAGE                                                                   *
*       This routine is C-callable and can be called as:                    *
*                                                                           *
*       void DSP_fir_cplx                                                   *
*       (                                                                   *
*           const short *restrict x,                                        *
*           const short *restrict h,                                        *
*           short       *restrict r,                                        *
*           short                 nh,                                       *
*           short                 nr                                        *
*      )                                                                    *
*                                                                           *
*      x[2*(nr+nh-1)] : Complex input data. x must point to x[2*(nh-1)].    *
*      h[2*nh]        : Complex coefficients (in normal order).             *
*      r[2*nr]        : Complex output data.                                *
*      nh             : Number of complex coefficients.                     *
*                       Must be multiple of 2.                              *
*      nr             : Number of complex output samples.                   *
*                       Must be multiple of 4.                              *
*                                                                           *
*   DESCRIPTION                                                             *
*       This complex FIR computes nr complex output samples using nh        *
*       complex coefficients. It operates on 16-bit data with a 32-bit      *
*       accumulate. Each array consists of an even and odd term with even   *
*       terms representing the real part of the element and the odd terms   *
*       the imaginary part. The pointer to input array x must point to the  *
*       (nh)th complex sample, i.e. element 2*(nh-1), upon entry to the     *
*       function. The coefficients are expected in normal order.            *
*                                                                           *
*   C CODE                                                                  *
*       void DSP_fir_cplx                                                   *
*       (                                                                   *
*           const short *restrict x,                                        *
*           const short *restrict h,                                        *
*           short *restrict r,                                              *
*           short nh,                                                       *
*           short nr                                                        *
*       )                                                                   *
*       {                                                                   *
*           short i,j;                                                      *
*           int imag, real;                                                 *
*                                                                           *
*           for (i = 0; i < 2*nr; i += 2)                                   *
*           {                                                               *
*               imag = 0;                                                   *
*               real = 0;                                                   *
*               for (j = 0; j < 2*nh; j += 2)                               *
*               {                                                           *
*                   real += h[j] * x[i-j]   - h[j+1] * x[i+1-j];            *
*                   imag += h[j] * x[i+1-j] + h[j+1] * x[i-j];              *
*               }                                                           *
*               r[i]   = (real >> 15);                                      *
*               r[i+1] = (imag >> 15);                                      *
*           }                                                               *
*       }                                                                   *
*                                                                           *
*   TECHNIQUES                                                              *
*       Outer loop is unrolled 4 times while inner loop is not unrolled.    *
*       Both inner and outer loops are collapsed into one loop.             *
*       ADDAH and SUBAH are used alongwith PACKH2 to perform accumulation,  *
*       shift and data packing.                                             *
*       Collpsed one stage of epilog and prolog each.                       *
*                                                                           *
*   ASSUMPTIONS                                                             *
*       nr must be a multiple of 4 and >= 4.                                *
*       nh must be a multiple of 2 and >= 2.                                *
*                                                                           *
*   MEMORY NOTE                                                             *
*       No memory bank hits under any conditions.                           *
*                                                                           *
*   NOTE                                                                    *
*       This function is little Endian.                                     *
*       This function is interrupt-tolerant but not interruptible.          *
*                                                                           *
*   CYCLES                                                                  *
*       nh * nr + 24                                                        *
*                                                                           *
*       For nh = 24, nr = 40, 984 cycles                                    *
*                                                                           *
*   CODESIZE                                                                *
*      432 bytes                                                            *
*                                                                           *
* ------------------------------------------------------------------------- *
*             Copyright (c) 2003 Texas Instruments, Incorporated.           *
*                            All Rights Reserved.                           *
* ========================================================================= *

        .global _DSP_fir_cplx

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