197 lines
8.2 KiB
NASM
197 lines
8.2 KiB
NASM
;;#############################################################################
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;;! \file source/fir32.asm
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;;!
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;;! \brief 32-bit FIR filter
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;;!
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;;! \date Jan 11, 2011
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;;!
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;;
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;;#############################################################################
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;;!
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;;! Copyright: Copyright (C) 2023 Texas Instruments Incorporated -
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;;! All rights reserved not granted herein.
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;;! Limited License.
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;;!
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;;! Texas Instruments Incorporated grants a world-wide, royalty-free,
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;;! non-exclusive license under copyrights and patents it now or hereafter
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;;! owns or controls to make, have made, use, import, offer to sell and sell
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;;! ("Utilize") this software subject to the terms herein. With respect to the
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;;! foregoing patent license, such license is granted solely to the extent that
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;;! any such patent is necessary to Utilize the software alone. The patent
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;;! license shall not apply to any combinations which include this software,
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;;! other than combinations with devices manufactured by or for TI
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;;! ("TI Devices").
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;;! No hardware patent is licensed hereunder.
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;;!
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;;! Redistributions must preserve existing copyright notices and reproduce this
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;;! license (including the above copyright notice and the disclaimer and
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;;! (if applicable) source code license limitations below) in the documentation
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;;! and/or other materials provided with the distribution.
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;;!
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;;! Redistribution and use in binary form, without modification, are permitted
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;;! provided that the following conditions are met:
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;;!
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;;! * No reverse engineering, decompilation, or disassembly of this software is
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;;! permitted with respect to any software provided in binary form.
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;;! * Any redistribution and use are licensed by TI for use only
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;;! with TI Devices.
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;;! * Nothing shall obligate TI to provide you with source code for the
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;;! software licensed and provided to you in object code.
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;;!
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;;! If software source code is provided to you, modification and redistribution
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;;! of the source code are permitted provided that the following conditions
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;;! are met:
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;;!
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;;! * any redistribution and use of the source code, including any resulting
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;;! derivative works, are licensed by TI for use only with TI Devices.
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;;! * any redistribution and use of any object code compiled from the source
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;;! code and any resulting derivative works, are licensed by TI for use
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;;! only with TI Devices.
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;;!
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;;! Neither the name of Texas Instruments Incorporated nor the names of its
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;;! suppliers may be used to endorse or promote products derived from this
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;;! software without specific prior written permission.
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;;#############################################################################
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;;
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;;*****************************************************************************
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;; includes
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;;*****************************************************************************
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;;
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;;*****************************************************************************
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;; globals
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;;*****************************************************************************
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; Module definition for external reference
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.if __TI_EABI__
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.asg FIR32_init, _FIR32_init
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.asg FIR32_calc, _FIR32_calc
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.endif
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.def _FIR32_init
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.def _FIR32_calc
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;;
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;;=============================================================================
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;; Routine Type : C Callable
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;; Description :
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;; void FIR16_calc(FIR16_handle)
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;;
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;; This routine implements the non-recursive difference equation of an
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;; all-zero filter(FIR), of order N. All the coefficients of all-zero
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;; filter are assumed to be less than 1 in magnitude.
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;;=============================================================================
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;;
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;; Difference Equation :
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;;
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;; y(n)=H(0)*x(n)+H(1)*x(n-1)+H(2)*x(n-2)+....+H(N)*x(n-N)
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;;
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;; where
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;; y(n)=output sample of the filter at index n
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;; x(n)=input sample of the filter at index n
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;;
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;; Transfer Function :
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;;
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;; Y(z) -1 -2 -N+1 -N
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;; ----- = h(0) + h(1) z + h(2) z + ... +h(N-1) z + h(N) z
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;; X(z)
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;;
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;; Network Diagram :
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;
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;; dbuffer[0] dbuffer[1] dbuffer[2] dbuffer[N}
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;; Input -1 x(n-1) -1 x(n-2) x(n-N)
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;; x(n) >------o----z---->-o----z---->-o--- - ->- - o
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;; | | | |
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;; | | | |
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;; | | | |
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;; v H(0) v H(1) v H(2) v H(N)
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;; | | | |
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;; | | | | output
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;; |---->-----(+)---->----(+)-- - -> - (+)-----> y(n)
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;;
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;; Symbols Used :
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;; H(0),H(1),H(2),...,H(N) : filter coefficients
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;; x(n-1),x(n-2),...,x(n-N) : filter states
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;; x(n) : filter input
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;; y(n) : filter output
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;;=============================================================================
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;; Function Input: This function accepts the handle of the below structure
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;;
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;; typedef struct { <------------ XAR4
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;; int32_t *coeff_ptr; /* +0 Pointer to Filter coefficient */
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;; int32_t * dbuffer_ptr; /* +2 Delay buffer ptr */
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;; int16_t cbindex; /* +4 Circular Buffer Index */
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;; int16_t order; /* +5 Order of the Filter */
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;; int16_t input; /* +6 Latest Input sample */
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;; int16_t output; /* +7 Filter Output */
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;; void (*init)(void *); /* +8 Ptr to Init funtion */
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;; void (*calc)(void *); /* +10 Ptr to calc fn */
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;; }FIR32;
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;;
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_FIR32_init:
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ADDB XAR4,#2
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MOV *+XAR4[4],#0 ; XAR4->ouput, input=0
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MOV *+XAR4[6],#0 ; output=0
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MOVL XAR6,*XAR4 ; XAR6=dbuffer_ptr
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MOV ACC,*+XAR4[3] << 1 ; AL=2*order
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MOV AH,AL ; AH=2*order
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ADDB AL,#1 ; AL=2*order+1
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MOV *+XAR4[2],AH ; cbindex = 2*order (will wrap around if offset > 2*order)
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RPT AL
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|| MOV *XAR6++,#0
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LRETR
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ConstTable:
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PosSatVal: .long 0x00FFFFFF ; Corresponds to >> 6
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NegSatVal: .long 0xFF000000 ; Corresponds to >> 6
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FILTER_SIZE .set 44
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_FIR32_calc:
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PUSH XAR1 ; Context Save
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SETC SXM,OVM ; AR4=FIR16_handle->coeff_ptr
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SPM 0 ; Create guard band of >> 6
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MOVL XAR7,*XAR4 ; XAR4->coeff_ptr, XAR7=coeff_ptr
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MOVZ AR1,*+XAR4[4] ; XAR4->coeff_ptr, AR1=cbindex
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MOVL XAR6,*+XAR4[2] ; XAR4->coeff_ptr, XAR6=dbuffer_ptr
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MOVL ACC,*+XAR4[6] ; ACC = X:Input
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MOVL *XAR6%++,ACC ; Store in data array and inc circ address
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MOVL *+XAR4[2],XAR6 ; XAR4->coeff_ptr, update the dbuffer pointer
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MOV ACC,*+XAR4[5] ; AR0=order
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MOVZ AR0,AL ; AR0=order
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ZAPA ; Zero the ACC, P registers and OVC counter
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;; <<VC140828 - debug only
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;;.asg 0, N
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;;.loop
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;;QMACL P,*+XAR6[AR1%++],*XAR7++ ; ACC = ACC + P << PM = ACC + P << 0
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;; ; P = (signed[*+XAR6[AR1%++]] * signed[*XAR7++]) >> 32
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;;.eval N + 1, N ; increment N
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;;.break N = FILTER_SIZE
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;;.endloop
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;; VC140828>>
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RPT AR0
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|| QMACL P,*XAR6%++,*XAR7++
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ADDL ACC,P ; Add the two sums with shift
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ADDB XAR4,#1
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MOVL *+XAR4[7],ACC ; Store saturated result (Q30)
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SPM 0
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POP XAR1
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CLRC OVM
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LRETR
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;;#############################################################################
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;; End of File
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;;#############################################################################
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