/* ======================================================================== */
/* TEXAS INSTRUMENTS, INC. */
/* */
/* DSPLIB DSP Signal Processing Library */
/* */
/* Release: Version 1.02 */
/* CVS Revision: 1.5 Fri Mar 29 15:47:22 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 */
/* iir */
/* */
/* */
/* REVISION DATE */
/* 11-Feb-2002 */
/* */
/* USAGE */
/* This routine is C callable and can be called as: */
/* */
/* void DSP_iir */
/* ( */
/* short *restrict r1, // Output array (used) // */
/* const short *x, // Input array // */
/* short *restrict r2, // Output array (stored) // */
/* const short *h2, // Filter Coeffs. AR part // */
/* const short *h1, // Filter Coeffs. FIR part // */
/* int nr // Number of output samples // */
/* ) */
/* */
/* DESCRIPTION */
/* The IIR performs an auto-regressive moving-average (ARMA) filter */
/* with 4 auto-regressive filter coefficients and 5 moving-average */
/* filter coefficients for nr output samples. The output vector is */
/* stored in two locations. This routine is used as a high pass */
/* filter in the VSELP vocoder. */
/* */
/* C CODE */
/* void DSP_iir */
/* ( */
/* short *restrict r1, // Output array (used) // */
/* const short *x, // Input array // */
/* short *restrict r2, // Output array (stored) // */
/* const short *h2, // Filter Coeffs. AR part // */
/* const short *h1, // Filter Coeffs. FIR part // */
/* int nr // Number of output samples // */
/* ) */
/* { */
/* int j, i; */
/* int sum; */
/* */
/* for (i = 0; i < nr; i++) */
/* { */
/* sum = h2[0] * x[4+i]; */
/* */
/* for (j = 1; j <= 4; j++) */
/* sum += h2[j] * x[4+i-j] - h1[j] * r1[4+i-j]; */
/* */
/* r1[4+i] = (sum >> 15); */
/* r2[ i] = r1[4+i]; */
/* } */
/* } */
/* */
/* TECHNIQUES */
/* The inner loop is completely unrolled and software pipelined */
/* (i.e. each time the 5 cycle loop "LOOP" is executed the inner */
/* loop of the C code is executed.) */
/* */
/* MEMORY NOTE */
/* This code is ENDIAN NEUTRAL. */
/* This code is interrupt-tolerant but not interruptible. */
/* */
/* MEMORY NOTE */
/* To avoid memory hits r1[] and r2[] must be aligned on the next word */
/* boundary following the alignment of x[], e.g.: */
/* #pragma DATA_MEM_BANK(x, 0); */
/* #pragma DATA_MEM_BANK(r1, 2); */
/* #pragma DATA_MEM_BANK(r2, 2); */
/* */
/* CYCLES */
/* 5 * nr + 30 */
/* */
/* For nr = 40: 230 cycles */
/* */
/* CODESIZE */
/* 384 bytes */
/* */
/* ------------------------------------------------------------------------ */
/* Copyright (c) 2002 Texas Instruments, Incorporated. */
/* All Rights Reserved. */
/* ======================================================================== */
#ifndef DSP_IIR_H_
#define DSP_IIR_H_ 1
void DSP_iir
(
short *restrict r1, /* Output array (used); */
const short *x, /* Input array */
short *restrict r2, /* Output array (stored); */
const short *h2, /* Filter Coeffs. AR part */
const short *h1, /* Filter Coeffs. FIR part */
int nr /* Number of output samples */
);
#endif
/* ======================================================================== */
/* End of file: dsp_iir.h */
/* ------------------------------------------------------------------------ */
/* Copyright (c) 2002 Texas Instruments, Incorporated. */
/* All Rights Reserved. */
/* ======================================================================== */