/*************************************************************************** * __________ __ ___. * Open \______ \ ____ ____ | | _\_ |__ _______ ___ * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ * \/ \/ \/ \/ \/ * $Id$ * * Copyright (C) 2006 Thom Johansen * * All files in this archive are subject to the GNU General Public License. * See the file COPYING in the source tree root for full license agreement. * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY * KIND, either express or implied. * ****************************************************************************/ .section .text .global apply_crossfeed apply_crossfeed: lea.l (-44, %sp), %sp movem.l %d2-%d7/%a2-%a6, (%sp) | save all regs move.l (44+4, %sp), %a4 movem.l (%a4), %a4-%a5 | a4 = src[0], a5 = src[1] move.l (44+8, %sp), %d7 | d7 = count lea.l crossfeed_data, %a1 lea.l (8*4, %a1), %a0 | a0 = &delay[0][0] move.l (%a1)+, %a6 | a6 = direct gain movem.l (3*4, %a1), %d0-%d3 | fetch filter history samples move.l (33*4, %a1), %d4 | fetch delay line index movem.l (%a1), %a1-%a3 | load filter coefs move.l %d4, %d5 lsl.l #3, %d5 add.l %d5, %a0 | point a0 to current delay position | lea.l (%d4*4, %a0), %a0 | lea.l (%d4*4, %a0), %a0 | point a0 to current delay position /* Register usage in loop: * a0 = &delay[index][0], a1..a3 = b0, b1, a1 (filter coefs), * a4 = src[0], a5 = src[1], a6 = direct gain, * d0..d3 = history * d4 = delay line index, * d5,d6 = temp. * d7 = count */ .cfloop: mac.l %a2, %d0, (4, %a0), %d0, %acc0 | acc = b1*dr[n - 1] d0 = dr[n] mac.l %a1, %d0, %acc0 | acc += b0*dr[n] mac.l %a3, %d1, (%a4), %d5, %acc0 | acc += a1*y_l[n - 1], load left input move.l %acc0, %d1 | get filtered delayed sample mac.l %a6, %d5, %acc0 | acc += gain*x_l[n] movclr.l %acc0, %d6 move.l %d6, (%a4)+ | write result mac.l %a2, %d2, (%a0), %d2, %acc0 | acc = b1*dl[n - 1], d2 = dl[n] move.l %d5, (%a0)+ | save left input to delay line mac.l %a1, %d2, %acc0 | acc += b0*dl[n] mac.l %a3, %d3, (%a5), %d5, %acc0 | acc += a1*y_r[n - 1], load right input move.l %acc0, %d3 | get filtered delayed sample mac.l %a6, %d5, %acc0 | acc += gain*x_r[n] move.l %d5, (%a0)+ | save right input to delay line movclr.l %acc0, %d6 move.l %d6, (%a5)+ | write result addq.l #1, %d4 | index++ moveq.l #13, %d6 cmp.l %d6, %d4 | wrap index to 0 if it overflows jlt .nowrap moveq.l #13*8, %d4 sub.l %d4, %a0 | wrap back delay line ptr as well clr.l %d4 .nowrap: subq.l #1, %d7 jne .cfloop | save data back to struct lea.l crossfeed_data + 4*4, %a1 movem.l %d0-%d3, (%a1) move.l %d4, (30*4, %a1) movem.l (%sp), %d2-%d7/%a2-%a6 lea.l (44, %sp), %sp rts