/* ======================================================================== */
/* TEXAS INSTRUMENTS, INC. */
/* */
/* DSPLIB DSP Signal Processing Library */
/* */
/* Release: Version 1.02 */
/* CVS Revision: 1.5 Fri Mar 22 02:07:52 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_sym: Symmetric FIR Filter */
/* */
/* USAGE */
/* This routine is C-callable and can be called as: */
/* */
/* void DSP_fir_sym */
/* ( */
/* short *restrict x, */
/* short *restrict h, */
/* short *restrict r, */
/* int nh, */
/* int nr, */
/* int s */
/* ); */
/* */
/* x[nr+2*nh] : Pointer to input array of size nr + 2*nh */
/* h[nh+1] : Pointer to coefficient array of size nh + 1 */
/* Must be word aligned. */
/* r[nr] : Pointer to output array of size nr */
/* nh : Number of coefficients. */
/* Must be multiple of 8. */
/* nr : Number of output samples. */
/* Must be multiple of 2. */
/* s : Number of insignificant digits to truncate */
/* */
/* DESCRIPTION */
/* This symmetric FIR filter assumes the number of filter */
/* coefficients is 2*nh + 1. It operates on 16-bit data with a 40-bit */
/* accumulation. The filter computes nr output samples. */
/* */
/* C CODE */
/* void DSP_fir_sym */
/* ( */
/* short *restrict x, */
/* short *restrict h, */
/* short *restrict r, */
/* int nh, */
/* int nr, */
/* int s */
/* ) */
/* { */
/* int i, j; */
/* long y0; */
/* long round = (long) 1 << (s - 1); */
/* */
/* for (j = 0; j < nr; j++) */
/* { */
/* y0 = round; */
/* */
/* for (i = 0; i < nh; i++) */
/* y0 += (short) (x[j + i] + x[j + 2 * nh - i]) * h[i]; */
/* */
/* y0 += x[j + nh] * h[nh]; */
/* r[j] = (int) (y0 >> s); */
/* } */
/* } */
/* */
/* TECHNIQUES */
/* Load word instruction is used to simultaneously load two */
/* values from h[] in a single clock cycle. */
/* The inner loop is unrolled eight times. */
/* The outer loop is unrolled eight times. */
/* Both the inner and outer loops are software pipelined. */
/* */
/* ASSUMPTIONS */
/* This code is Little Endian. */
/* nh must be a multiple of 8 and >= 8. */
/* nr must be a multiple of 2. */
/* h[] must be word-aligned. */
/* */
/* MEMORY NOTE */
/* No memory bank hits under any conditions. */
/* */
/* CYCLES */
/* (3 * nh/2 + 10) * nr/2 + 20 */
/* For nh=24, nr=42: 986 cycles */
/* */
/* CODESIZE */
/* 416 bytes */
/* */
/* ------------------------------------------------------------------------ */
/* Copyright (c) 2002 Texas Instruments, Incorporated. */
/* All Rights Reserved. */
/* ======================================================================== */
#ifndef DSP_FIR_SYM_H_
#define DSP_FIR_SYM_H_ 1
void DSP_fir_sym
(
short *restrict x,
short *restrict h,
short *restrict r,
int nh,
int nr,
int s
);
#endif
/* ======================================================================== */
/* End of file: dsp_fir_sym.h */
/* ------------------------------------------------------------------------ */
/* Copyright (c) 2002 Texas Instruments, Incorporated. */
/* All Rights Reserved. */
/* ======================================================================== */