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131 lines
9.8 KiB
131 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: 1.5 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_r8: FIR Filter (radix 8) *
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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_r8 *
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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_r8 *
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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 8 *
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* Number of samples: 'nr' >= 4, multiple of 4 *
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* Array 'r' is word aligned. *
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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 load *
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* four values in a single clock cycle. *
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* *
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* 2. The inner loop is unrolled four times and will always *
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* compute a multiple of 4 of nr. *
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* *
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* 3. The outer loop is conditionally exected in parallel with the *
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* inner loop. This allows for a zero overhead outer loop. *
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* *
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* CYCLES *
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* nh * nr/4 + 17 *
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* *
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* For nh = 32 and nr = 36, cycles = 305. *
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* *
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* CODESIZE *
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* 336 bytes. *
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* *
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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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.global _DSP_fir_r8
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* ========================================================================= *
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* End of file: dsp_fir_r8.h64 *
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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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