/*************************************************************************** * __________ __ ___. * Open \______ \ ____ ____ | | _\_ |__ _______ ___ * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ * \/ \/ \/ \/ \/ * $Id$ * * Copyright (C) 2006 Thom Johansen * Portions Copyright (C) 2007 Michael Sevakis * * 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. * ****************************************************************************/ /**************************************************************************** * void dsp_apply_gain(int count, struct dsp_data *data, int32_t *buf[]) */ .section .text .align 2 .global dsp_apply_gain dsp_apply_gain: lea.l -20(%sp), %sp | save registers movem.l %d2-%d4/%a2-%a3, (%sp) | movem.l 28(%sp), %a0-%a1 | %a0 = data, | %a1 = buf move.l 4(%a0), %d1 | %d1 = data->num_channels move.l 32(%a0), %a0 | %a0 = data->gain (in s8.23) 10: | channel loop | move.l 24(%sp), %d0 | %d0 = count move.l -4(%a1, %d1.l*4), %a2 | %a2 = s = buf[ch-1] move.l %a2, %a3 | %a3 = d = s move.l (%a2)+, %d2 | %d2 = *s++, mac.l %a0, %d2, (%a2)+, %d2, %acc0 | %acc0 = S(n)*gain, load S(n+1) subq.l #1, %d0 | --count > 0 ? : effectively n++ ble.b 30f | loop done | no? finish up 20: | loop | move.l %accext01, %d4 | fetch S(n-1)[7:0] movclr.l %acc0, %d3 | fetch S(n-1)[40:8] in %d5[31:0] asl.l #8, %d3 | *s++ = (S(n-1)[40:8] << 8) | S(n-1)[7:0] mac.l %a0, %d2, (%a2)+, %d2, %acc0 | %acc0 = S(n)*gain, load S(n+1) move.b %d4, %d3 | move.l %d3, (%a3)+ | subq.l #1, %d0 | --count > 0 ? : effectively n++ bgt.b 20b | loop | yes? do more samples 30: | loop done | move.l %accext01, %d4 | fetch S(n-1)[7:0] movclr.l %acc0, %d3 | fetch S(n-1)[40:8] in %d5[31:0] asl.l #8, %d3 | *s = (S(n-1)[40:8] << 8) | S(n-1)[7:0] move.b %d4, %d3 | move.l %d3, (%a3) | subq.l #1, %d1 | next channel bgt.b 10b | channel loop | movem.l (%sp), %d2-%d4/%a2-%a3 | restore registers lea.l 20(%sp), %sp | cleanup stack rts | .size dsp_apply_gain,.-dsp_apply_gain /**************************************************************************** * void apply_crossfeed(int count, int32_t *buf[]) */ .section .text .align 2 .global apply_crossfeed apply_crossfeed: lea.l -44(%sp), %sp | movem.l %d2-%d7/%a2-%a6, (%sp) | save all regs movem.l 48(%sp), %d7/%a4 | %d7 = count, %a4 = src movem.l (%a4), %a4-%a5 | %a4 = src[0], %a5 = src[1] lea.l crossfeed_data, %a1 | %a1 = &crossfeed_data move.l (%a1)+, %d6 | %d6 = direct gain movem.l 12(%a1), %d0-%d3 | fetch filter history samples move.l 132(%a1), %a0 | fetch delay line address movem.l (%a1), %a1-%a3 | load filter coefs lea.l crossfeed_data+136, %a6 | %a6 = delay line wrap limit bra.b 20f | loop start | go to loop start point /* Register usage in loop: * %a0 = delay_p, %a1..%a3 = b0, b1, a1 (filter coefs), * %a4 = buf[0], %a5 = buf[1], * %a6 = delay line pointer wrap limit, * %d0..%d3 = history * %d4..%d5 = temp. * %d6 = direct gain, * %d7 = count */ 10: | loop | movclr.l %acc0, %d4 | write outputs move.l %d4, (%a4)+ | . movclr.l %acc1, %d5 | . move.l %d5, (%a5)+ | . 20: | loop start | mac.l %a2, %d0, (%a0)+, %d0, %acc0 | %acc0 = b1*dl[n - 1], %d0 = dl[n] mac.l %a1, %d0 , %acc0 | %acc0 += b0*dl[n] mac.l %a3, %d1, (%a5), %d5, %acc0 | %acc0 += a1*y_r[n - 1], load R mac.l %a2, %d2, (%a0)+, %d2, %acc1 | %acc1 = b1*dr[n - 1], %d2 = dr[n] mac.l %a1, %d2 , %acc1 | %acc1 += b0*dr[n] mac.l %a3, %d3, (%a4), %d4, %acc1 | %acc1 += a1*y_l[n - 1], load L movem.l %d4-%d5, -8(%a0) | save left & right inputs to delay line move.l %acc0, %d3 | get filtered delayed left sample (y_l[n]) move.l %acc1, %d1 | get filtered delayed right sample (y_r[n]) mac.l %d6, %d4, %acc0 | %acc0 += gain*x_l[n] mac.l %d6, %d5, %acc1 | %acc1 += gain*x_r[n] cmp.l %a6, %a0 | wrap %a0 if passed end bhs.b 30f | wrap buffer | .word 0x51fb | tpf.l | trap the buffer wrap 30: | wrap buffer | ...fwd taken branches more costly lea.l -104(%a0), %a0 | wrap it up subq.l #1, %d7 | --count > 0 ? bgt.b 10b | loop | yes? do more movclr.l %acc0, %d4 | write last outputs move.l %d4, (%a4) | . movclr.l %acc1, %d5 | . move.l %d5, (%a5) | . lea.l crossfeed_data+16, %a1 | save data back to struct movem.l %d0-%d3, (%a1) | ...history move.l %a0, 120(%a1) | ...delay_p movem.l (%sp), %d2-%d7/%a2-%a6 | restore all regs lea.l 44(%sp), %sp | rts | .size apply_crossfeed,.-apply_crossfeed /**************************************************************************** * int dsp_downsample(int count, struct dsp_data *data, * in32_t *src[], int32_t *dst[]) */ .section .text .align 2 .global dsp_downsample dsp_downsample: lea.l -40(%sp), %sp | save non-clobberables movem.l %d2-%d7/%a2-%a5, (%sp) | movem.l 44(%sp), %d2/%a0-%a2 | %d2 = count | %a0 = data | %a1 = src | %a2 = dst movem.l 4(%a0), %d3-%d4 | %d3 = ch = data->num_channels | %d4 = delta = data->resample_data.delta moveq.l #16, %d7 | %d7 = shift 10: | channel loop | move.l 12(%a0), %d5 | %d5 = phase = data->resample_data.phase move.l -4(%a1, %d3.l*4), %a3 | %a3 = s = src[ch-1] move.l -4(%a2, %d3.l*4), %a4 | %a4 = d = dst[ch-1] lea.l 12(%a0, %d3.l*4), %a5 | %a5 = &data->resample_data.ast_sample[ch-1] move.l (%a5), %d0 | %d0 = last = data->resample_data.last_sample[ch-1] move.l -4(%a3, %d2.l*4), (%a5) | data->resample_data.last_sample[ch-1] = s[count-1] move.l %d5, %d6 | %d6 = pos = phase >> 16 lsr.l %d7, %d6 | cmp.l %d2, %d6 | past end of samples? bge.b 40f | skip resample loop| yes? skip loop tst.l %d6 | need last sample of prev. frame? bne.b 20f | resample loop | no? start main loop move.l (%a3, %d6.l*4), %d1 | %d1 = s[pos] bra.b 30f | resample start last | start with last (last in %d0) 20: | resample loop | lea.l -4(%a3, %d6.l*4), %a5 | load s[pos-1] and s[pos] movem.l (%a5), %d0-%d1 | 30: | resample start last | sub.l %d0, %d1 | %d1 = diff = s[pos] - s[pos-1] move.l %d0, %acc0 | %acc0 = previous sample move.l %d5, %d0 | frac = (phase << 16) >> 1 lsl.l %d7, %d0 | lsr.l #1, %d0 | mac.l %d0, %d1, %acc0 | %acc0 += frac * diff add.l %d4, %d5 | phase += delta move.l %d5, %d6 | pos = phase >> 16 lsr.l %d7, %d6 | movclr.l %acc0, %d0 | move.l %d0, (%a4)+ | *d++ = %d0 cmp.l %d2, %d6 | pos < count? blt.b 20b | resample loop | yes? continue resampling 40: | skip resample loop | subq.l #1, %d3 | ch > 0? bgt.b 10b | channel loop | yes? process next channel lsl.l %d7, %d2 | wrap phase to start of next frame sub.l %d2, %d5 | data->resample_data.phase = move.l %d5, 12(%a0) | ... phase - (count << 16) move.l %a4, %d0 | return d - d[0] sub.l (%a2), %d0 | asr.l #2, %d0 | convert bytes->samples movem.l (%sp), %d2-%d7/%a2-%a5 | restore non-clobberables lea.l 40(%sp), %sp | cleanup stack rts | buh-bye .size dsp_downsample,.-dsp_downsample /**************************************************************************** * int dsp_upsample(int count, struct dsp_data *dsp, * int32_t *src[], int32_t *dst[]) */ .section .text .align 2 .global dsp_upsample dsp_upsample: lea.l -40(%sp), %sp | save non-clobberables movem.l %d2-%d7/%a2-%a5, (%sp) | movem.l 44(%sp), %d2/%a0-%a2 | %d2 = count | %a0 = data | %a1 = src | %a2 = dst movem.l 4(%a0), %d3-%d4 | %d3 = ch = channels | %d4 = delta = data->resample_data.delta swap %d4 | swap delta to high word to use... | ...carries to increment position 10: | channel loop | move.l 12(%a0), %d5 | %d5 = phase = data->resample_data.phase move.l -4(%a1, %d3.l*4), %a3 | %a3 = s = src[ch-1] lea.l 12(%a0, %d3.l*4), %a4 | %a4 = &data->resample_data.last_sample[ch-1] lea.l -4(%a3, %d2.l*4), %a5 | %a5 = src_end = &src[count-1] move.l (%a4), %d0 | %d0 = last = data->resample_data.last_sample[ch-1] move.l (%a5), (%a4) | data->resample_data.last_sample[ch-1] = s[count-1] move.l -4(%a2, %d3.l*4), %a4 | %a4 = d = dst[ch-1] move.l (%a3)+, %d1 | fetch first sample - might throw this... | ...away later but we'll be preincremented move.l %d1, %d6 | save sample value sub.l %d0, %d1 | %d1 = diff = s[0] - last swap %d5 | swap phase to high word to use | carries to increment position move.l %d5, %d7 | %d7 = pos = phase >> 16 clr.w %d5 | eor.l %d5, %d7 | pos == 0? beq.b 40f | loop start | yes? start loop cmp.l %d2, %d7 | past end of samples? bge.b 50f | skip resample loop| yes? go to next channel and collect info lea.l (%a3, %d7.l*4), %a3 | %a3 = s = &s[pos+1] movem.l -8(%a3), %d0-%d1 | %d0 = s[pos-1], %d1 = s[pos] move.l %d1, %d6 | save sample value sub.l %d0, %d1 | %d1 = diff = s[pos] - s[pos-1] bra.b 40f | loop start | 20: | next sample loop | move.l %d6, %d0 | move previous sample to %d0 move.l (%a3)+, %d1 | fetch next sample move.l %d1, %d6 | save sample value sub.l %d0, %d1 | %d1 = diff = s[pos] - s[pos-1] 30: | same sample loop | movclr.l %acc0, %d7 | %d7 = result move.l %d7, (%a4)+ | *d++ = %d7 40: | loop start | lsr.l #1, %d5 | make phase into frac move.l %d0, %acc0 | %acc0 = s[pos-1] mac.l %d1, %d5, %acc0 | %acc0 = diff * frac lsl.l #1, %d5 | restore frac to phase add.l %d4, %d5 | phase += delta bcc.b 30b | same sample loop | load next values? cmp.l %a5, %a3 | src <= src_end? bls.b 20b | next sample loop | yes? continue resampling movclr.l %acc0, %d7 | %d7 = result move.l %d7, (%a4)+ | *d++ = %d7 50: | skip resample loop | subq.l #1, %d3 | ch > 0? bgt.b 10b | channel loop | yes? process next channel swap %d5 | wrap phase to start of next frame move.l %d5, 12(%a0) | ...and save in data->resample_data.phase move.l %a4, %d0 | return d - d[0] sub.l (%a2), %d0 | movem.l (%sp), %d2-%d7/%a2-%a5 | restore non-clobberables asr.l #2, %d0 | convert bytes->samples lea.l 40(%sp), %sp | cleanup stack rts | buh-bye .size dsp_upsample,.-dsp_upsample /**************************************************************************** * void channels_process_sound_chan_mono(int count, int32_t *buf[]) * * Mix left and right channels 50/50 into a center channel. */ .section .text .align 2 .global channels_process_sound_chan_mono channels_process_sound_chan_mono: movem.l 4(%sp), %d0/%a0 | %d0 = count, %a0 = buf lea.l -20(%sp), %sp | save registers movem.l %d2-%d4/%a2-%a3, (%sp) | movem.l (%a0), %a0-%a1 | get channel pointers move.l %a0, %a2 | use separate dst pointers since read move.l %a1, %a3 | pointers run one ahead of write move.l #0x40000000, %d3 | %d3 = 0.5 move.l (%a0)+, %d1 | prime the input registers move.l (%a1)+, %d2 | mac.l %d1, %d3, (%a0)+, %d1, %acc0 | mac.l %d2, %d3, (%a1)+, %d2, %acc0 | subq.l #1, %d0 | ble.s 20f | loop done | 10: | loop | movclr.l %acc0, %d4 | L = R = l/2 + r/2 mac.l %d1, %d3, (%a0)+, %d1, %acc0 | mac.l %d2, %d3, (%a1)+, %d2, %acc0 | move.l %d4, (%a2)+ | output to original buffer move.l %d4, (%a3)+ | subq.l #1, %d0 | bgt.s 10b | loop | 20: | loop done | movclr.l %acc0, %d4 | output last sample move.l %d4, (%a2) | move.l %d4, (%a3) | movem.l (%sp), %d2-%d4/%a2-%a3 | restore registers lea.l 20(%sp), %sp | cleanup rts | .size channels_process_sound_chan_mono, \ .-channels_process_sound_chan_mono /**************************************************************************** * void channels_process_sound_chan_custom(int count, int32_t *buf[]) * * Apply stereo width (narrowing/expanding) effect. */ .section .text .align 2 .global channels_process_sound_chan_custom channels_process_sound_chan_custom: movem.l 4(%sp), %d0/%a0 | %d0 = count, %a0 = buf lea.l -28(%sp), %sp | save registers movem.l %d2-%d6/%a2-%a3, (%sp) | movem.l (%a0), %a0-%a1 | get channel pointers move.l %a0, %a2 | use separate dst pointers since read move.l %a1, %a3 | pointers run one ahead of write move.l dsp_sw_gain, %d3 | load straight (mid) gain move.l dsp_sw_cross, %d4 | load cross (side) gain move.l (%a0)+, %d1 | prime the input registers move.l (%a1)+, %d2 | mac.l %d1, %d3 , %acc0 | L = l*gain + r*cross mac.l %d1, %d4, (%a0)+, %d1, %acc1 | R = r*gain + l*cross mac.l %d2, %d4 , %acc0 | mac.l %d2, %d3, (%a1)+, %d2, %acc1 | subq.l #1, %d0 | ble.b 20f | loop done | 10: | loop | movclr.l %acc0, %d5 | movclr.l %acc1, %d6 | mac.l %d1, %d3 , %acc0 | L = l*gain + r*cross mac.l %d1, %d4, (%a0)+, %d1, %acc1 | R = r*gain + l*cross mac.l %d2, %d4 , %acc0 | mac.l %d2, %d3, (%a1)+, %d2, %acc1 | move.l %d5, (%a2)+ | move.l %d6, (%a3)+ | subq.l #1, %d0 | bgt.s 10b | loop | 20: | loop done | movclr.l %acc0, %d5 | output last sample movclr.l %acc1, %d6 | move.l %d5, (%a2) | move.l %d6, (%a3) | movem.l (%sp), %d2-%d6/%a2-%a3 | restore registers lea.l 28(%sp), %sp | cleanup rts | .size channels_process_sound_chan_custom, \ .-channels_process_sound_chan_custom /**************************************************************************** * void channels_process_sound_chan_karaoke(int count, int32_t *buf[]) * * Separate channels into side channels. */ .section .text .align 2 .global channels_process_sound_chan_karaoke channels_process_sound_chan_karaoke: movem.l 4(%sp), %d0/%a0 | %d0 = count, %a0 = buf lea.l -20(%sp), %sp | save registers movem.l %d2-%d4/%a2-%a3, (%sp) | movem.l (%a0), %a0-%a1 | get channel src pointers move.l %a0, %a2 | use separate dst pointers since read move.l %a1, %a3 | pointers run one ahead of write move.l #0x40000000, %d3 | %d3 = 0.5 move.l (%a0)+, %d1 | prime the input registers move.l (%a1)+, %d2 | mac.l %d1, %d3, (%a0)+, %d1, %acc0 | L = l/2 - r/2 msac.l %d2, %d3, (%a1)+, %d2, %acc0 | subq.l #1, %d0 | ble.b 20f | loop done | 10: | loop | movclr.l %acc0, %d4 | mac.l %d1, %d3, (%a0)+, %d1, %acc0 | L = l/2 - r/2 msac.l %d2, %d3, (%a1)+, %d2, %acc0 | move.l %d4, (%a2)+ | neg.l %d4 | R = -L = -(l/2 - r/2) = r/2 - l/2 move.l %d4, (%a3)+ | subq.l #1, %d0 | bgt.s 10b | loop | 20: | loop done | movclr.l %acc0, %d4 | output last sample move.l %d4, (%a2) | neg.l %d4 | R = -L = -(l/2 - r/2) = r/2 - l/2 move.l %d4, (%a3) | movem.l (%sp), %d2-%d4/%a2-%a3 | restore registers lea.l 20(%sp), %sp | cleanup rts | .size channels_process_sound_chan_karaoke, \ .-channels_process_sound_chan_karaoke /**************************************************************************** * void sample_output_stereo(int count, struct dsp_data *data, * int32_t *src[], int16_t *dst) * * Framework based on the ubiquitous Rockbox line transfer logic for * Coldfire CPUs. * * Does emac clamping and scaling (which proved faster than the usual * checks and branches - even single test clamping) and writes using * line burst transfers. Also better than writing a single L-R pair per * loop but a good deal more code. * * Attemping bursting during reads is rather futile since the source and * destination alignments rarely agree and too much complication will * slow us up. The parallel loads seem to do a bit better at least until * a pcm buffer can always give line aligned chunk and then aligning the * dest can then imply the source is aligned if the source buffers are. * For now longword alignment is assumed of both the source and dest. * */ .section .text .align 2 .global sample_output_stereo sample_output_stereo: lea.l -48(%sp), %sp | save registers move.l %macsr, %d1 | do it now as at many lines will movem.l %d1-%d7/%a2-%a6, (%sp) | be the far more common condition move.l #0x80, %macsr | put emac unit in signed int mode movem.l 52(%sp), %a0-%a2/%a4 | lea.l (%a4, %a0.l*4), %a0 | %a0 = end address move.l (%a1), %d1 | %a1 = multiplier: (1 << (16 - scale)) sub.l #16, %d1 | neg.l %d1 | moveq.l #1, %d0 | asl.l %d1, %d0 | move.l %d0, %a1 | move.l #0x8000, %a6 | %a6 = rounding term movem.l (%a2), %a2-%a3 | get L/R channel pointers moveq.l #28, %d0 | %d0 = second line bound add.l %a4, %d0 | and.l #0xfffffff0, %d0 | cmp.l %a0, %d0 | at least a full line? bhi.w 40f | long loop 1 start | no? do as trailing longwords sub.l #16, %d0 | %d1 = first line bound cmp.l %a4, %d0 | any leading longwords? bls.b 20f | line loop start | no? start line loop 10: | long loop 0 | move.l (%a2)+, %d1 | read longword from L and R move.l %a6, %acc0 | move.l %acc0, %acc1 | mac.l %d1, %a1, (%a3)+, %d2, %acc0 | shift L to high word mac.l %d2, %a1, %acc1 | shift R to high word movclr.l %acc0, %d1 | get possibly saturated results movclr.l %acc1, %d2 | swap %d2 | move R to low word move.w %d2, %d1 | interleave MS 16 bits of each move.l %d1, (%a4)+ | ...and write both cmp.l %a4, %d0 | bhi.b 10b | long loop 0 | 20: | line loop start | lea.l -12(%a0), %a5 | %a5 = at or just before last line bound 30: | line loop | move.l (%a3)+, %d4 | get next 4 R samples and scale move.l %a6, %acc0 | move.l %acc0, %acc1 | move.l %acc1, %acc2 | move.l %acc2, %acc3 | mac.l %d4, %a1, (%a3)+, %d5, %acc0 | with saturation mac.l %d5, %a1, (%a3)+, %d6, %acc1 | mac.l %d6, %a1, (%a3)+, %d7, %acc2 | mac.l %d7, %a1, (%a2)+, %d0, %acc3 | lea.l 16(%a4), %a4 | increment dest here, mitigate stalls movclr.l %acc0, %d4 | obtain R results movclr.l %acc1, %d5 | movclr.l %acc2, %d6 | movclr.l %acc3, %d7 | move.l %a6, %acc0 | move.l %acc0, %acc1 | move.l %acc1, %acc2 | move.l %acc2, %acc3 | mac.l %d0, %a1, (%a2)+, %d1, %acc0 | get next 4 L samples and scale mac.l %d1, %a1, (%a2)+, %d2, %acc1 | with saturation mac.l %d2, %a1, (%a2)+, %d3, %acc2 | mac.l %d3, %a1 , %acc3 | swap %d4 | a) interleave most significant... swap %d5 | swap %d6 | swap %d7 | movclr.l %acc0, %d0 | obtain L results movclr.l %acc1, %d1 | movclr.l %acc2, %d2 | movclr.l %acc3, %d3 | move.w %d4, %d0 | a) ... 16 bits of L and R move.w %d5, %d1 | move.w %d6, %d2 | move.w %d7, %d3 | movem.l %d0-%d3, -16(%a4) | write four stereo samples cmp.l %a4, %a5 | bhi.b 30b | line loop | 40: | long loop 1 start | cmp.l %a4, %a0 | any longwords left? bls.b 60f | output end | no? stop 50: | long loop 1 | move.l (%a2)+, %d1 | handle trailing longwords move.l %a6, %acc0 | move.l %acc0, %acc1 | mac.l %d1, %a1, (%a3)+, %d2, %acc0 | the same way as leading ones mac.l %d2, %a1, %acc1 | movclr.l %acc0, %d1 | movclr.l %acc1, %d2 | swap %d2 | move.w %d2, %d1 | move.l %d1, (%a4)+ | cmp.l %a4, %a0 | bhi.b 50b | long loop 1 60: | output end | movem.l (%sp), %d1-%d7/%a2-%a6 | restore registers move.l %d1, %macsr | lea.l 48(%sp), %sp | cleanup rts | .size sample_output_stereo, .-sample_output_stereo /**************************************************************************** * void sample_output_mono(int count, struct dsp_data *data, * int32_t *src[], int16_t *dst) * * Same treatment as sample_output_stereo but for one channel. */ .section .text .align 2 .global sample_output_mono sample_output_mono: lea.l -32(%sp), %sp | save registers move.l %macsr, %d1 | do it now as at many lines will movem.l %d1-%d5/%a2-%a4, (%sp) | be the far more common condition move.l #0x80, %macsr | put emac unit in signed int mode movem.l 36(%sp), %a0-%a3 | lea.l (%a3, %a0.l*4), %a0 | %a0 = end address move.l (%a1), %d1 | %d5 = multiplier: (1 << (16 - scale)) sub.l #16, %d1 | neg.l %d1 | moveq.l #1, %d5 | asl.l %d1, %d5 | move.l #0x8000, %a4 | %a4 = rounding term movem.l (%a2), %a2 | get source channel pointer moveq.l #28, %d0 | %d0 = second line bound add.l %a3, %d0 | and.l #0xfffffff0, %d0 | cmp.l %a0, %d0 | at least a full line? bhi.w 40f | long loop 1 start | no? do as trailing longwords sub.l #16, %d0 | %d1 = first line bound cmp.l %a3, %d0 | any leading longwords? bls.b 20f | line loop start | no? start line loop 10: | long loop 0 | move.l (%a2)+, %d1 | read longword from L and R move.l %a4, %acc0 | mac.l %d1, %d5, %acc0 | shift L to high word movclr.l %acc0, %d1 | get possibly saturated results move.l %d1, %d2 | swap %d2 | move R to low word move.w %d2, %d1 | duplicate single channel into move.l %d1, (%a3)+ | L and R cmp.l %a3, %d0 | bhi.b 10b | long loop 0 | 20: | line loop start | lea.l -12(%a0), %a1 | %a1 = at or just before last line bound 30: | line loop | move.l (%a2)+, %d0 | get next 4 L samples and scale move.l %a4, %acc0 | move.l %acc0, %acc1 | move.l %acc1, %acc2 | move.l %acc2, %acc3 | mac.l %d0, %d5, (%a2)+, %d1, %acc0 | with saturation mac.l %d1, %d5, (%a2)+, %d2, %acc1 | mac.l %d2, %d5, (%a2)+, %d3, %acc2 | mac.l %d3, %d5 , %acc3 | lea.l 16(%a3), %a3 | increment dest here, mitigate stalls movclr.l %acc0, %d0 | obtain results movclr.l %acc1, %d1 | movclr.l %acc2, %d2 | movclr.l %acc3, %d3 | move.l %d0, %d4 | duplicate single channel swap %d4 | into L and R move.w %d4, %d0 | move.l %d1, %d4 | swap %d4 | move.w %d4, %d1 | move.l %d2, %d4 | swap %d4 | move.w %d4, %d2 | move.l %d3, %d4 | swap %d4 | move.w %d4, %d3 | movem.l %d0-%d3, -16(%a3) | write four stereo samples cmp.l %a3, %a1 | bhi.b 30b | line loop | 40: | long loop 1 start | cmp.l %a3, %a0 | any longwords left? bls.b 60f | output end | no? stop 50: | loop loop 1 | move.l (%a2)+, %d1 | handle trailing longwords move.l %a4, %acc0 | mac.l %d1, %d5, %acc0 | the same way as leading ones movclr.l %acc0, %d1 | move.l %d1, %d2 | swap %d2 | move.w %d2, %d1 | move.l %d1, (%a3)+ | cmp.l %a3, %a0 | bhi.b 50b | long loop 1 | 60: | output end | movem.l (%sp), %d1-%d5/%a2-%a4 | restore registers move.l %d1, %macsr | lea.l 32(%sp), %sp | cleanup rts | .size sample_output_mono, .-sample_output_mono