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