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135 lines
9.8 KiB
135 lines
9.8 KiB
/* ======================================================================== */
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/* TEXAS INSTRUMENTS, INC. */
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/* */
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/* DSPLIB DSP Signal Processing Library */
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/* */
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/* Release: Revision 1.04b */
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/* CVS Revision: 1.7 Sun Sep 29 03:32:22 2002 (UTC) */
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/* Snapshot date: 23-Oct-2003 */
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/* */
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/* This library contains proprietary intellectual property of Texas */
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/* Instruments, Inc. The library and its source code are protected by */
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/* various copyrights, and portions may also be protected by patents or */
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/* other legal protections. */
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/* */
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/* This software is licensed for use with Texas Instruments TMS320 */
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/* family DSPs. This license was provided to you prior to installing */
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/* the software. You may review this license by consulting the file */
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/* TI_license.PDF which accompanies the files in this library. */
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/* ------------------------------------------------------------------------ */
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/* Copyright (C) 2003 Texas Instruments, Incorporated. */
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/* All Rights Reserved. */
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/* ======================================================================== */
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/* ======================================================================== */
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/* Assembler compatibility shim for assembling 4.30 and later code on */
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/* tools prior to 4.30. */
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/* ======================================================================== */
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/* ======================================================================== */
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/* End of assembler compatibility shim. */
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/* ======================================================================== */
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/* ======================================================================== */
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/* TEXAS INSTRUMENTS, INC. */
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/* */
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/* NAME */
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/* DSP_fir_r4: FIR Filter (radix 4) */
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/* */
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/* */
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/* REVISION DATE */
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/* 10-Aug-2001 */
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/* */
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/* USAGE */
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/* This routine is C-callable and can be called as: */
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/* */
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/* void DSP_fir_r4 */
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/* ( */
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/* const short *restrict x, // Input array [nr+nh-1 elements] // */
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/* const short *restrict h, // Coeff array [nh elements] // */
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/* short *restrict r, // Output array [nr elements] // */
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/* int nh, // Number of coefficients. // */
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/* int nr // Number of output samples. // */
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/* ) */
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/* */
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/* ARGUMENTS PASSED */
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/* *x -> A4 */
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/* *h -> B4 */
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/* *r -> A6 */
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/* nh -> B6 */
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/* nr -> A8 */
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/* */
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/* DESCRIPTION */
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/* Computes a real FIR filter (direct-form) using coefficients */
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/* stored in vector h. The real data input is stored in vector x. */
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/* The filter output result is stored in vector r. Input data and */
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/* filter taps are 16-bit, with intermediate values kept at 32-bit */
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/* precision. Filter taps are expected in Q15 format. */
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/* */
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/* The following is a natural C implementation with no restrictions. */
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/* This version has restrictions as noted in the ASSUMPTIONS below. */
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/* */
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/* void DSP_fir_r4 */
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/* ( */
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/* const short *restrict x, */
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/* const short *restrict h, */
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/* short *restrict r, */
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/* int nh, */
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/* int nr */
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/* ) */
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/* { */
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/* int i, j, sum; */
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/* */
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/* for (j = 0; j < nr; j++) */
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/* { */
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/* sum = 0; */
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/* for (i = 0; i < nh; i++) */
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/* sum += x[i + j] * h[i]; */
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/* r[j] = sum >> 15; */
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/* } */
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/* } */
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/* */
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/* ASSUMPTIONS */
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/* Number of taps: 'nh' >= 8, multiple of 4 */
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/* Number of samples: 'nr' >= 4, multiple of 4 */
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/* */
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/* NOTES */
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/* This function blocks interrupts for its entire duration. It is */
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/* interrupt tolerant, but not interruptible. */
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/* */
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/* MEMORY NOTE */
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/* No memory bank hits under any conditions. */
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/* This code is a LITTLE ENDIAN implementation */
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/* */
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/* TECHNIQUES */
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/* 1. Load double word instruction is used to simultaneously */
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/* load four values in a single clock cycle. */
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/* 2. The inner loop is unrolled four times */
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/* */
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/* CYCLES */
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/* (8 + nh) * nr/4 + 9 */
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/* */
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/* For nh = 12 and nr = 12, cycles = 69 */
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/* */
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/* CODESIZE */
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/* 308 bytes. */
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/* ------------------------------------------------------------------------ */
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/* Copyright (c) 2003 Texas Instruments, Incorporated. */
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/* All Rights Reserved. */
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/* ======================================================================== */
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#ifndef DSP_FIR_R4_H_
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#define DSP_FIR_R4_H_ 1
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void DSP_fir_r4
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(
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const short *restrict x, /* Input array [nr+nh-1 elements] */
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const short *restrict h, /* Coeff array [nh elements] */
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short *restrict r, /* Output array [nr elements] */
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int nh, /* Number of coefficients. */
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int nr /* Number of output samples. */
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);
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#endif
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/* ======================================================================== */
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/* End of file: dsp_fir_r4.h */
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/* ------------------------------------------------------------------------ */
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/* Copyright (c) 2003 Texas Instruments, Incorporated. */
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/* All Rights Reserved. */
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/* ======================================================================== */
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