/*************************************************************************** * __________ __ ___. * Open \______ \ ____ ____ | | _\_ |__ _______ ___ * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ * \/ \/ \/ \/ \/ * $Id$ * * Copyright (C) 2005 by 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. * ****************************************************************************/ /* The following is an assembler optimised version of the LPC filtering routines needed for FLAC decoding. It is optimised for use with the MCF5249 processor, or any other similar ColdFire core with the EMAC unit. All LPC filtering up to order 8 is done in specially optimised unrolled loops, while every order above this is handled by a slower default routine. */ .section .icode,"ax",@progbits .global lpc_decode_emac .align 2 lpc_decode_emac: lea.l (-40, %sp), %sp movem.l %d2-%d7/%a2-%a5, (%sp) movem.l (40+4, %sp), %d0-%d2/%a0-%a1 /* d0 = blocksize, d1 = qlevel, d2 = pred_order a0 = data, a1 = coeffs */ /* the data pointer always lags behind history pointer by 'pred_order' samples. since we have one loop for each order, we can hard code this and free a register by not saving data pointer. */ move.l %d2, %d3 neg.l %d3 lea.l (%a0, %d3.l*4), %a0 | history clr.l %d3 move.l %d3, %macsr | we'll need integer mode for this tst.l %d0 jeq .exit | zero samples to process, exit moveq.l #8, %d3 cmp.l %d3, %d2 jgt .default | order is over 8, jump to default case jmp.l (2, %pc, %d2.l*4) | jump to loop corresponding to pred_order .jumptable: bra.w .exit | zero order filter isn't possible, exit function bra.w .order1 bra.w .order2 bra.w .order3 bra.w .order4 bra.w .order5 bra.w .order6 bra.w .order7 | last jump table entry coincides with target, so leave it out .order8: movem.l (%a1), %d3-%d7/%a2-%a4 | load lpc coefs move.l (%a0)+, %a5 | load first history sample .loop8: mac.l %a5, %a4, (%a0)+, %a5, %acc0 mac.l %a5, %a3, (%a0)+, %a5, %acc0 mac.l %a5, %a2, (%a0)+, %a5, %acc0 mac.l %a5, %d7, (%a0)+, %a5, %acc0 mac.l %a5, %d6, (%a0)+, %a5, %acc0 mac.l %a5, %d5, (%a0)+, %a5, %acc0 mac.l %a5, %d4, (%a0)+, %a5, %acc0 mac.l %a5, %d3, (-7*4, %a0), %a5, %acc0 | load for the next iteration movclr.l %acc0, %d2 | get sum asr.l %d1, %d2 | shift sum by lp_quantization bits add.l %d2, (%a0) | add residual and save lea.l (-6*4, %a0), %a0 | point history back at second element subq.l #1, %d0 | decrement counter jne .loop8 | are we done? jra .exit .order7: movem.l (%a1), %d3-%d7/%a2-%a3 move.l (%a0)+, %a5 .loop7: mac.l %a5, %a3, (%a0)+, %a5, %acc0 mac.l %a5, %a2, (%a0)+, %a5, %acc0 mac.l %a5, %d7, (%a0)+, %a5, %acc0 mac.l %a5, %d6, (%a0)+, %a5, %acc0 mac.l %a5, %d5, (%a0)+, %a5, %acc0 mac.l %a5, %d4, (%a0)+, %a5, %acc0 mac.l %a5, %d3, (-6*4, %a0), %a5, %acc0 movclr.l %acc0, %d2 asr.l %d1, %d2 add.l %d2, (%a0) lea.l (-5*4, %a0), %a0 subq.l #1, %d0 jne .loop7 jra .exit .order6: movem.l (%a1), %d3-%d7/%a2 move.l (%a0)+, %a5 .loop6: mac.l %a5, %a2, (%a0)+, %a5, %acc0 mac.l %a5, %d7, (%a0)+, %a5, %acc0 mac.l %a5, %d6, (%a0)+, %a5, %acc0 mac.l %a5, %d5, (%a0)+, %a5, %acc0 mac.l %a5, %d4, (%a0)+, %a5, %acc0 mac.l %a5, %d3, (-5*4, %a0), %a5, %acc0 movclr.l %acc0, %d2 asr.l %d1, %d2 add.l %d2, (%a0) lea.l (-4*4, %a0), %a0 subq.l #1, %d0 jne .loop6 jra .exit .order5: movem.l (%a1), %d3-%d7 move.l (%a0)+, %a5 .loop5: mac.l %a5, %d7, (%a0)+, %a5, %acc0 mac.l %a5, %d6, (%a0)+, %a5, %acc0 mac.l %a5, %d5, (%a0)+, %a5, %acc0 mac.l %a5, %d4, (%a0)+, %a5, %acc0 mac.l %a5, %d3, (-4*4, %a0), %a5, %acc0 movclr.l %acc0, %d2 asr.l %d1, %d2 add.l %d2, (%a0) lea.l (-3*4, %a0), %a0 subq.l #1, %d0 jne .loop5 jra .exit .order4: movem.l (%a1), %d3-%d6 move.l (%a0)+, %a5 .loop4: mac.l %a5, %d6, (%a0)+, %a5, %acc0 mac.l %a5, %d5, (%a0)+, %a5, %acc0 mac.l %a5, %d4, (%a0)+, %a5, %acc0 mac.l %a5, %d3, (-3*4, %a0), %a5, %acc0 movclr.l %acc0, %d2 asr.l %d1, %d2 add.l %d2, (%a0) subq.l #8, %a0 subq.l #1, %d0 jne .loop4 jra .exit .order3: movem.l (%a1), %d3-%d5 move.l (%a0)+, %a5 .loop3: mac.l %a5, %d5, (%a0)+, %a5, %acc0 mac.l %a5, %d4, (%a0)+, %a5, %acc0 mac.l %a5, %d3, (-2*4, %a0), %a5, %acc0 movclr.l %acc0, %d2 asr.l %d1, %d2 add.l %d2, (%a0) subq.l #4, %a0 subq.l #1, %d0 jne .loop3 jra .exit .order2: movem.l (%a1), %d3-%d4 move.l (%a0)+, %a5 .loop2: mac.l %a5, %d4, (%a0)+, %a5, %acc0 mac.l %a5, %d3, %acc0 | data for next iteration is already loaded movclr.l %acc0, %d2 asr.l %d1, %d2 add.l %d2, (%a0) subq.l #1, %d0 jne .loop2 jra .exit .order1: | no point in using mac here move.l (%a1), %d3 .loop1: move.l %d3, %d2 muls.l (%a0)+, %d2 asr.l %d1, %d2 add.l %d2, (%a0) subq.l #1, %d0 jne .loop1 jra .exit .default: /* we do the filtering in an unrolled by 4 loop as far as we can, and then do the rest in an ordinary one by one sample loop. */ lea.l (%a1, %d2.l*4), %a2 | need to start in the other end of coefs move.l %a0, %a3 | working copy of history pointer move.l %d2, %d3 lsr.l #2, %d3 | coefs/4, num of iterations needed in next loop move.l (%a3)+, %a5 | preload data for loop .dloop1: lea.l (-4*4, %a2), %a2 | move lpc coef pointer four samples backwards movem.l (%a2), %d4-%d7 | load four coefs mac.l %a5, %d7, (%a3)+, %a5, %acc0 mac.l %a5, %d6, (%a3)+, %a5, %acc0 mac.l %a5, %d5, (%a3)+, %a5, %acc0 mac.l %a5, %d4, (%a3)+, %a5, %acc0 subq.l #1, %d3 | any more unrolled loop operations left? jne .dloop1 move.l %d2, %d3 moveq.l #3, %d4 | mask 0x00000003 and.l %d4, %d3 | get the remaining samples to be filtered jeq .dsave | no remaining samples .dloop2: move.l -(%a2), %d4 | get lpc coef mac.l %a5, %d4, (%a3)+, %a5, %acc0 subq.l #1, %d3 | any more iterations left? jne .dloop2 .dsave: movclr.l %acc0, %d3 | get result asr.l %d1, %d3 | shift lp_quantization bits right subq.l #4, %a3 | we're one past the save location add.l %d3, (%a3) | add residual and save addq.l #4, %a0 | increment history pointer subq.l #1, %d0 | decrement data_len jne .default | are we done? | if so, fall through to exit .exit: movem.l (%sp), %d2-%d7/%a2-%a5 lea.l (40, %sp), %sp rts