475 lines
17 KiB
ArmAsm
475 lines
17 KiB
ArmAsm
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2006 by David Bryant
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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/* This is an assembly optimized version of the following WavPack function:
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*
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* void decorr_stereo_pass_cont_arm (struct decorr_pass *dpp,
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* long *buffer, long sample_count);
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*
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* It performs a single pass of stereo decorrelation on the provided buffer.
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* Note that this version of the function requires that the 8 previous stereo
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* samples are visible and correct. In other words, it ignores the "samples_*"
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* fields in the decorr_pass structure and gets the history data directly
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* from the buffer. It does, however, return the appropriate history samples
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* to the decorr_pass structure before returning.
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*
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* This is written to work on a ARM7TDMI processor. This version only uses the
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* 32-bit multiply-accumulate instruction and so will overflow with 24-bit
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* WavPack files.
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*/
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.text
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.align
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.global decorr_stereo_pass_cont_arm
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/*
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* on entry:
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*
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* r0 = struct decorr_pass *dpp
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* r1 = long *buffer
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* r2 = long sample_count
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*/
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decorr_stereo_pass_cont_arm:
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stmfd sp!, {r4 - r8, r10, r11, lr}
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mov r5, r0 @ r5 = dpp
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mov r11, #512 @ r11 = 512 for rounding
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ldrsh r6, [r0, #2] @ r6 = dpp->delta
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ldrsh r4, [r0, #4] @ r4 = dpp->weight_A
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ldrsh r0, [r0, #6] @ r0 = dpp->weight_B
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cmp r2, #0 @ exit if no samples to process
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beq common_exit
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add r7, r1, r2, asl #3 @ r7 = buffer ending position
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ldrsh r2, [r5, #0] @ r2 = dpp->term
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cmp r2, #0
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bmi minus_term
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ldr lr, [r1, #-16] @ load 2 sample history from buffer
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ldr r10, [r1, #-12] @ for terms 2, 17, and 18
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ldr r8, [r1, #-8]
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ldr r3, [r1, #-4]
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cmp r2, #17
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beq term_17_loop
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cmp r2, #18
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beq term_18_loop
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cmp r2, #2
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beq term_2_loop
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b term_default_loop @ else handle default (1-8, except 2)
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minus_term:
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mov r10, #1024 @ r10 = -1024 for weight clipping
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rsb r10, r10, #0 @ (only used for negative terms)
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cmn r2, #1
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beq term_minus_1
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cmn r2, #2
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beq term_minus_2
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cmn r2, #3
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beq term_minus_3
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b common_exit
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/*
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******************************************************************************
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* Loop to handle term = 17 condition
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*
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* r0 = dpp->weight_B r8 = previous left sample
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* r1 = bptr r9 =
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* r2 = current sample r10 = second previous left sample
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* r3 = previous right sample r11 = 512 (for rounding)
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* r4 = dpp->weight_A ip = current decorrelation value
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* r5 = dpp sp =
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* r6 = dpp->delta lr = second previous right sample
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* r7 = eptr pc =
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*******************************************************************************
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*/
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term_17_loop:
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rsbs ip, lr, r8, asl #1 @ decorr value = (2 * prev) - 2nd prev
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mov lr, r8 @ previous becomes 2nd previous
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ldr r2, [r1], #4 @ get sample & update pointer
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mla r8, ip, r4, r11 @ mult decorr value by weight, round,
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add r8, r2, r8, asr #10 @ shift, and add to new sample
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strne r8, [r1, #-4] @ if change possible, store sample back
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cmpne r2, #0
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beq .L325
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teq ip, r2 @ update weight based on signs
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submi r4, r4, r6
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addpl r4, r4, r6
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.L325: rsbs ip, r10, r3, asl #1 @ do same thing for right channel
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mov r10, r3
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ldr r2, [r1], #4
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mla r3, ip, r0, r11
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add r3, r2, r3, asr #10
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strne r3, [r1, #-4]
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cmpne r2, #0
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beq .L329
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teq ip, r2
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submi r0, r0, r6
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addpl r0, r0, r6
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.L329: cmp r7, r1 @ loop back if more samples to do
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bhi term_17_loop
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b store_1718 @ common exit for terms 17 & 18
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/*
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******************************************************************************
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* Loop to handle term = 18 condition
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*
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* r0 = dpp->weight_B r8 = previous left sample
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* r1 = bptr r9 =
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* r2 = current sample r10 = second previous left sample
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* r3 = previous right sample r11 = 512 (for rounding)
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* r4 = dpp->weight_A ip = decorrelation value
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* r5 = dpp sp =
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* r6 = dpp->delta lr = second previous right sample
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* r7 = eptr pc =
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*******************************************************************************
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*/
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term_18_loop:
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sub ip, r8, lr @ decorr value =
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mov lr, r8 @ ((3 * prev) - 2nd prev) >> 1
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adds ip, r8, ip, asr #1
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ldr r2, [r1], #4 @ get sample & update pointer
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mla r8, ip, r4, r11 @ mult decorr value by weight, round,
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add r8, r2, r8, asr #10 @ shift, and add to new sample
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strne r8, [r1, #-4] @ if change possible, store sample back
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cmpne r2, #0
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beq .L337
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teq ip, r2 @ update weight based on signs
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submi r4, r4, r6
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addpl r4, r4, r6
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.L337: sub ip, r3, r10 @ do same thing for right channel
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mov r10, r3
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adds ip, r3, ip, asr #1
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ldr r2, [r1], #4
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mla r3, ip, r0, r11
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add r3, r2, r3, asr #10
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strne r3, [r1, #-4]
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cmpne r2, #0
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beq .L341
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teq ip, r2
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submi r0, r0, r6
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addpl r0, r0, r6
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.L341: cmp r7, r1 @ loop back if more samples to do
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bhi term_18_loop
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/* common exit for terms 17 & 18 */
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store_1718:
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str r3, [r5, #40] @ store sample history into struct
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str r8, [r5, #8]
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str r10, [r5, #44]
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str lr, [r5, #12]
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b common_exit @ and return
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/*
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******************************************************************************
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* Loop to handle term = 2 condition
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* (note that this case can be handled by the default term handler (1-8), but
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* this special case is faster because it doesn't have to read memory twice)
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*
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* r0 = dpp->weight_B r8 = previous left sample
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* r1 = bptr r9 =
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* r2 = current sample r10 = second previous left sample
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* r3 = previous right sample r11 = 512 (for rounding)
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* r4 = dpp->weight_A ip = decorrelation value
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* r5 = dpp sp =
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* r6 = dpp->delta lr = second previous right sample
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* r7 = eptr pc =
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*******************************************************************************
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*/
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term_2_loop:
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movs ip, lr @ get decorrelation value & test
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mov lr, r8 @ previous becomes 2nd previous
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ldr r2, [r1], #4 @ get sample & update pointer
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mla r8, ip, r4, r11 @ mult decorr value by weight, round,
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add r8, r2, r8, asr #10 @ shift, and add to new sample
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strne r8, [r1, #-4] @ if change possible, store sample back
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cmpne r2, #0
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beq .L225
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teq ip, r2 @ update weight based on signs
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submi r4, r4, r6
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addpl r4, r4, r6
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.L225: movs ip, r10 @ do same thing for right channel
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mov r10, r3
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ldr r2, [r1], #4
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mla r3, ip, r0, r11
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add r3, r2, r3, asr #10
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strne r3, [r1, #-4]
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cmpne r2, #0
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beq .L229
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teq ip, r2
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submi r0, r0, r6
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addpl r0, r0, r6
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.L229: cmp r7, r1 @ loop back if more samples to do
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bhi term_2_loop
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b default_term_exit @ this exit updates all dpp->samples
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/*
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******************************************************************************
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* Loop to handle default term condition
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*
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* r0 = dpp->weight_B r8 = result accumulator
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* r1 = bptr r9 =
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* r2 = dpp->term r10 =
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* r3 = decorrelation value r11 = 512 (for rounding)
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* r4 = dpp->weight_A ip = current sample
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* r5 = dpp sp =
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* r6 = dpp->delta lr =
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* r7 = eptr pc =
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*******************************************************************************
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*/
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term_default_loop:
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ldr ip, [r1] @ get original sample
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ldr r3, [r1, -r2, asl #3] @ get decorrelation value based on term
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mla r8, r3, r4, r11 @ mult decorr value by weight, round,
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add r8, ip, r8, asr #10 @ shift and add to new sample
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str r8, [r1], #4 @ store update sample
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cmp r3, #0
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cmpne ip, #0
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beq .L350
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teq ip, r3 @ update weight based on signs
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submi r4, r4, r6
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addpl r4, r4, r6
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.L350: ldr ip, [r1] @ do the same thing for right channel
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ldr r3, [r1, -r2, asl #3]
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mla r8, r3, r0, r11
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add r8, ip, r8, asr #10
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str r8, [r1], #4
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cmp r3, #0
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cmpne ip, #0
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beq .L354
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teq ip, r3
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submi r0, r0, r6
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addpl r0, r0, r6
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.L354: cmp r7, r1 @ loop back if more samples to do
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bhi term_default_loop
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/*
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* This exit is used by terms 1-8 to store the previous 8 samples into the decorr
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* structure (even if they are not all used for the given term)
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*/
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default_term_exit:
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ldrsh r3, [r5, #0]
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sub ip, r3, #1
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mov lr, #7
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.L358: and r3, ip, #7
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add r3, r5, r3, asl #2
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ldr r2, [r1, #-4]
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str r2, [r3, #40]
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ldr r2, [r1, #-8]!
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str r2, [r3, #8]
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sub ip, ip, #1
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sub lr, lr, #1
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cmn lr, #1
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bne .L358
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b common_exit
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/*
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******************************************************************************
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* Loop to handle term = -1 condition
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*
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* r0 = dpp->weight_B r8 =
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* r1 = bptr r9 =
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* r2 = intermediate result r10 = -1024 (for clipping)
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* r3 = previous right sample r11 = 512 (for rounding)
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* r4 = dpp->weight_A ip = current sample
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* r5 = dpp sp =
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* r6 = dpp->delta lr = updated left sample
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* r7 = eptr pc =
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*******************************************************************************
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*/
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term_minus_1:
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ldr r3, [r1, #-4]
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term_minus_1_loop:
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ldr ip, [r1] @ for left channel the decorrelation value
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mla r2, r3, r4, r11 @ is the previous right sample (in r3)
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add lr, ip, r2, asr #10
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str lr, [r1], #8
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cmp r3, #0
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cmpne ip, #0
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beq .L361
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teq ip, r3 @ update weight based on signs
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submi r4, r4, r6
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addpl r4, r4, r6
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cmp r4, #1024
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movgt r4, #1024
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cmp r4, r10
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movlt r4, r10
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.L361: ldr r2, [r1, #-4] @ for right channel the decorrelation value
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mla r3, lr, r0, r11 @ is the just updated right sample (in lr)
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add r3, r2, r3, asr #10
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str r3, [r1, #-4]
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cmp lr, #0
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cmpne r2, #0
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beq .L369
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teq r2, lr
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submi r0, r0, r6
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addpl r0, r0, r6
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cmp r0, #1024 @ then clip weight to +/-1024
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movgt r0, #1024
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cmp r0, r10
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movlt r0, r10
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.L369: cmp r7, r1 @ loop back if more samples to do
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bhi term_minus_1_loop
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str r3, [r5, #8] @ else store right sample and exit
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b common_exit
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/*
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******************************************************************************
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* Loop to handle term = -2 condition
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* (note that the channels are processed in the reverse order here)
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*
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* r0 = dpp->weight_B r8 =
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* r1 = bptr r9 =
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* r2 = intermediate result r10 = -1024 (for clipping)
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* r3 = previous left sample r11 = 512 (for rounding)
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* r4 = dpp->weight_A ip = current sample
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* r5 = dpp sp =
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* r6 = dpp->delta lr = updated right sample
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* r7 = eptr pc =
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*******************************************************************************
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*/
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term_minus_2:
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ldr r3, [r1, #-8]
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term_minus_2_loop:
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ldr ip, [r1, #4] @ for right channel the decorrelation value
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mla r2, r3, r0, r11 @ is the previous left sample (in r3)
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add lr, ip, r2, asr #10
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str lr, [r1, #4]
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cmp r3, #0
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cmpne ip, #0
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beq .L380
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teq ip, r3 @ update weight based on signs
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submi r0, r0, r6
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addpl r0, r0, r6
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cmp r0, #1024 @ then clip weight to +/-1024
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movgt r0, #1024
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cmp r0, r10
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movlt r0, r10
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.L380: ldr r2, [r1, #0] @ for left channel the decorrelation value
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mla r3, lr, r4, r11 @ is the just updated left sample (in lr)
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add r3, r2, r3, asr #10
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str r3, [r1], #8
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cmp lr, #0
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cmpne r2, #0
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beq .L388
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teq r2, lr
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submi r4, r4, r6
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addpl r4, r4, r6
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cmp r4, #1024
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movgt r4, #1024
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cmp r4, r10
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movlt r4, r10
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.L388: cmp r7, r1 @ loop back if more samples to do
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bhi term_minus_2_loop
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str r3, [r5, #40] @ else store left channel and exit
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b common_exit
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/*
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******************************************************************************
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* Loop to handle term = -3 condition
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*
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* r0 = dpp->weight_B r8 = previous left sample
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* r1 = bptr r9 =
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* r2 = current left sample r10 = -1024 (for clipping)
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* r3 = previous right sample r11 = 512 (for rounding)
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* r4 = dpp->weight_A ip = intermediate result
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* r5 = dpp sp =
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* r6 = dpp->delta lr =
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* r7 = eptr pc =
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*******************************************************************************
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*/
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term_minus_3:
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ldr r3, [r1, #-4] @ load previous samples
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ldr r8, [r1, #-8]
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term_minus_3_loop:
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ldr ip, [r1]
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mla r2, r3, r4, r11
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add r2, ip, r2, asr #10
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str r2, [r1], #4
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cmp r3, #0
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cmpne ip, #0
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beq .L399
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teq ip, r3 @ update weight based on signs
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submi r4, r4, r6
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addpl r4, r4, r6
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cmp r4, #1024 @ then clip weight to +/-1024
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movgt r4, #1024
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cmp r4, r10
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movlt r4, r10
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.L399: movs ip, r8 @ ip = previous left we use now
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mov r8, r2 @ r8 = current left we use next time
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ldr r2, [r1], #4
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mla r3, ip, r0, r11
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add r3, r2, r3, asr #10
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strne r3, [r1, #-4]
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cmpne r2, #0
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beq .L407
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teq ip, r2
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submi r0, r0, r6
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addpl r0, r0, r6
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cmp r0, #1024
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movgt r0, #1024
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cmp r0, r10
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movlt r0, r10
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.L407: cmp r7, r1 @ loop back if more samples to do
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bhi term_minus_3_loop
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str r3, [r5, #8] @ else store previous samples & exit
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str r8, [r5, #40]
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/*
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* Before finally exiting we must store weights back for next time
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*/
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common_exit:
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strh r4, [r5, #4]
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strh r0, [r5, #6]
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ldmfd sp!, {r4 - r8, r10, r11, pc}
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