Apple-2-SW/prog8
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prog8/examples/cx16/pcmaudio/stream-wav.p8
Irmen de Jong 6bc079c7b7 more asm symbol prefixing: variables with p8v_, subroutines with p8s_ etc 
labels with p8l_ . All this to avoid symbol clashes in the generated assembly code.
Everything got its own distinguishing prefix so we're done with it once and for all and have only 1 breaking change moment.
2023-12-20 22:20:59 +01:00

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;
; This program can stream a regular .wav file from the sdcard.
; It can be uncompressed or IMA-adpcm compressed (factor 4 lossy compression).
; See the "adpcm" module source for tips how to create those files.
;
; Note that 8 bit wav files are *unsigned* values whereas Vera wants *signed* values
; so these have to be converted on the fly. 16 bit wav files are signed already.
;
; The playback is done via AFLOW irq handler that fills the audio fifo buffer
; with around 1 Kb of new audio data. (copies raw pcm data or decodes adpcm block)
; In the meantime the main program loop reads new data blocks from the wav file
; as it is being played.
;
; NOTE: stripping the wav header and just having the raw pcm data in the file
; is slightly more efficient because the data blocks are then sector-aligned on the disk
;
%import diskio
%import floats
%import adpcm
%import wavfile
%import textio
%option no_sysinit
main {
str MUSIC_FILENAME = "?"*32
uword vera_rate_hz
ubyte vera_rate
sub start() {
txt.print("name of .wav file to play on drive 8: ")
while 0==txt.input_chars(MUSIC_FILENAME) {
; until user types a name...
}
prepare_music()
txt.print("\ngood file! playback starts! ")
cx16.rombank(0) ; activate kernal bank for faster calls
interrupts.wait()
interrupts.set_handler()
play_stuff()
txt.print("done!\n")
repeat { }
}
sub error(str msg) {
txt.print(msg)
repeat { }
}
sub prepare_music() {
txt.print("\nchecking ")
txt.print(MUSIC_FILENAME)
txt.nl()
bool wav_ok = false
if diskio.f_open(MUSIC_FILENAME) {
void diskio.f_read(music.buffer, 128)
wav_ok = wavfile.parse_header(music.buffer)
diskio.f_close()
}
if not wav_ok
error("no good wav file!")
calculate_vera_rate()
txt.print("wav format: ")
txt.print_ub(wavfile.wavefmt)
txt.print("\nchannels: ")
txt.print_ub(wavfile.nchannels)
txt.print("\nsample rate: ")
txt.print_uw(wavfile.sample_rate)
txt.print("\nbits per sample: ")
txt.print_uw(wavfile.bits_per_sample)
txt.print("\ndata size: ")
txt.print_uwhex(wavfile.data_size_hi, true)
txt.print_uwhex(wavfile.data_size_lo, false)
txt.print("\nvera rate: ")
txt.print_ub(vera_rate)
txt.print(" = ")
txt.print_uw(vera_rate_hz)
txt.print(" hz\n")
if wavfile.wavefmt==wavfile.WAVE_FORMAT_DVI_ADPCM {
txt.print("adpcm block size: ")
txt.print_uw(wavfile.block_align)
txt.nl()
}
if wavfile.nchannels>2 or
(wavfile.wavefmt!=wavfile.WAVE_FORMAT_DVI_ADPCM and wavfile.wavefmt!=wavfile.WAVE_FORMAT_PCM) or
wavfile.sample_rate > 48828 or
wavfile.bits_per_sample>16
error("unsupported format!")
if wavfile.wavefmt==wavfile.WAVE_FORMAT_DVI_ADPCM {
if(wavfile.block_align!=256) {
error("unsupported block alignment!")
}
}
cx16.VERA_AUDIO_RATE = 0 ; halt playback
cx16.VERA_AUDIO_CTRL = %10101011 ; mono 16 bit, volume 11
if wavfile.nchannels==2
cx16.VERA_AUDIO_CTRL = %10111011 ; stereo 16 bit, volume 11
if(wavfile.bits_per_sample==8)
cx16.VERA_AUDIO_CTRL &= %11011111 ; set to 8 bit instead
repeat 1024
cx16.VERA_AUDIO_DATA = 0 ; fill buffer with short silence
}
sub calculate_vera_rate() {
const float vera_freq_factor = 25e6 / 65536.0
vera_rate = (wavfile.sample_rate as float / vera_freq_factor) + 1.0 as ubyte
vera_rate_hz = (vera_rate as float) * vera_freq_factor as uword
}
sub play_stuff() {
if diskio.f_open(MUSIC_FILENAME) {
uword block_size = 1024
if wavfile.wavefmt==wavfile.WAVE_FORMAT_DVI_ADPCM
block_size = wavfile.block_align * 2 ; read 2 adpcm blocks at a time (512 bytes)
void diskio.f_read(music.buffer, wavfile.data_offset) ; skip to actual sample data start
music.pre_buffer(block_size)
cx16.VERA_AUDIO_RATE = vera_rate ; start audio playback
str progress_chars = "-\\|/-\\|/"
ubyte progress = 0
repeat {
interrupts.wait()
if interrupts.vsync {
interrupts.vsync=false
; ...do something triggered by vsync irq...
}
if interrupts.aflow {
interrupts.aflow=false
if not music.load_next_block(block_size)
break
; Note: copying the samples into the fifo buffer is done by the aflow interrupt handler itself.
txt.chrout(progress_chars[progress/2 & 7])
txt.chrout($9d) ; cursor left
progress++
}
}
diskio.f_close()
} else {
error("load error")
}
cx16.VERA_AUDIO_RATE = 0 ; halt playback
}
}
interrupts {
sub set_handler() {
sys.set_irqd()
cx16.CINV = &handler ; handles both AFLOW and VSYNC
cx16.VERA_IEN = %00001001 ; enable AFLOW + VSYNC
sys.clear_irqd()
}
bool aflow
bool vsync
asmsub wait() {
%asm {{
wai
}}
}
sub handler() {
if cx16.VERA_ISR & %00001000 {
; Filling the fifo is the only way to clear the Aflow irq.
; So we do this here, otherwise the aflow irq will keep triggering.
; Note that filling the buffer with fresh audio samples is NOT done here,
; but instead in the main program code that triggers on the 'aflow' being true!
cx16.save_virtual_registers()
music.aflow_play_block()
cx16.restore_virtual_registers()
aflow = true
}
if cx16.VERA_ISR & %00000001 {
cx16.VERA_ISR = %00000001
vsync = true
}
%asm {{
ply
plx
pla
rti
}}
}
}
music {
uword @requirezp nibblesptr
uword buffer = memory("buffer", 1024, 256)
sub pre_buffer(uword block_size) {
; pre-buffer first block
void diskio.f_read(buffer, block_size)
}
sub aflow_play_block() {
; play block that is currently in the buffer
if wavfile.wavefmt==wavfile.WAVE_FORMAT_DVI_ADPCM {
nibblesptr = buffer
if wavfile.nchannels==2 {
adpcm_block_stereo()
adpcm_block_stereo()
}
else {
adpcm_block_mono()
adpcm_block_mono()
}
}
else if wavfile.bits_per_sample==16
uncompressed_block_16()
else
uncompressed_block_8()
}
sub load_next_block(uword block_size) -> bool {
; read next block from disk into the buffer, for next time the irq triggers
return diskio.f_read(buffer, block_size) == block_size
}
asmsub uncompressed_block_8() {
; optimized loop to put 1024 bytes of data into the fifo as fast as possible
; converting unsigned wav 8 bit samples to signed 8 bit on the fly
%asm {{
lda p8v_buffer
sta cx16.r0L
lda p8v_buffer+1
sta cx16.r0H
ldx #4
- ldy #0
- lda (cx16.r0),y
eor #$80 ; convert to signed 8-bit
sta cx16.VERA_AUDIO_DATA
iny
bne -
inc cx16.r0H
dex
bne --
rts
}}
; original prog8 code:
; uword @requirezp ptr = main.start.buffer
; ubyte @requirezp sample
; repeat 1024 {
; sample = @(ptr) - 128
; cx16.VERA_AUDIO_DATA = sample
; ptr++
; }
}
asmsub uncompressed_block_16() {
; optimized loop to put 1024 bytes of data into the fifo as fast as possible
%asm {{
lda p8v_buffer
sta cx16.r0L
lda p8v_buffer+1
sta cx16.r0H
ldx #4
- ldy #0
- lda (cx16.r0),y
sta cx16.VERA_AUDIO_DATA
iny
bne -
inc cx16.r0H
dex
bne --
rts
}}
; original prog8 code:
; uword @requirezp ptr = main.start.buffer
; repeat 1024 {
; cx16.VERA_AUDIO_DATA = @(ptr)
; ptr++
; }
}
sub adpcm_block_mono() {
; refill the fifo buffer with one decoded adpcm block (1010 bytes of pcm data)
adpcm.init(peekw(nibblesptr), @(nibblesptr+2))
cx16.VERA_AUDIO_DATA = lsb(adpcm.predict)
cx16.VERA_AUDIO_DATA = msb(adpcm.predict)
nibblesptr += 4
ubyte @zp nibble
repeat 252/2 {
unroll 2 {
nibble = @(nibblesptr)
adpcm.decode_nibble(nibble & 15) ; first word
cx16.VERA_AUDIO_DATA = lsb(adpcm.predict)
cx16.VERA_AUDIO_DATA = msb(adpcm.predict)
adpcm.decode_nibble(nibble>>4) ; second word
cx16.VERA_AUDIO_DATA = lsb(adpcm.predict)
cx16.VERA_AUDIO_DATA = msb(adpcm.predict)
nibblesptr++
}
}
}
sub adpcm_block_stereo() {
; refill the fifo buffer with one decoded adpcm block (1010 bytes of pcm data)
adpcm.init(peekw(nibblesptr), @(nibblesptr+2)) ; left channel
cx16.VERA_AUDIO_DATA = lsb(adpcm.predict)
cx16.VERA_AUDIO_DATA = msb(adpcm.predict)
adpcm.init_second(peekw(nibblesptr+4), @(nibblesptr+6)) ; right channel
cx16.VERA_AUDIO_DATA = lsb(adpcm.predict_2)
cx16.VERA_AUDIO_DATA = msb(adpcm.predict_2)
nibblesptr += 8
repeat 248/8
decode_nibbles_unrolled()
}
sub decode_nibbles_unrolled() {
; decode 4 left channel nibbles
uword[8] left
uword[8] right
ubyte @requirezp nibble = @(nibblesptr)
adpcm.decode_nibble(nibble & 15) ; first word
left[0] = adpcm.predict
adpcm.decode_nibble(nibble>>4) ; second word
left[1] = adpcm.predict
nibble = @(nibblesptr+1)
adpcm.decode_nibble(nibble & 15) ; first word
left[2] = adpcm.predict
adpcm.decode_nibble(nibble>>4) ; second word
left[3] = adpcm.predict
nibble = @(nibblesptr+2)
adpcm.decode_nibble(nibble & 15) ; first word
left[4] = adpcm.predict
adpcm.decode_nibble(nibble>>4) ; second word
left[5] = adpcm.predict
nibble = @(nibblesptr+3)
adpcm.decode_nibble(nibble & 15) ; first word
left[6] = adpcm.predict
adpcm.decode_nibble(nibble>>4) ; second word
left[7] = adpcm.predict
; decode 4 right channel nibbles
nibble = @(nibblesptr+4)
adpcm.decode_nibble_second(nibble & 15) ; first word
right[0] = adpcm.predict_2
adpcm.decode_nibble_second(nibble>>4) ; second word
right[1] = adpcm.predict_2
nibble = @(nibblesptr+5)
adpcm.decode_nibble_second(nibble & 15) ; first word
right[2] = adpcm.predict_2
adpcm.decode_nibble_second(nibble>>4) ; second word
right[3] = adpcm.predict_2
nibble = @(nibblesptr+6)
adpcm.decode_nibble_second(nibble & 15) ; first word
right[4] = adpcm.predict_2
adpcm.decode_nibble_second(nibble>>4) ; second word
right[5] = adpcm.predict_2
nibble = @(nibblesptr+7)
adpcm.decode_nibble_second(nibble & 15) ; first word
right[6] = adpcm.predict_2
adpcm.decode_nibble_second(nibble>>4) ; second word
right[7] = adpcm.predict_2
nibblesptr += 8
%asm {{
; copy to vera PSG fifo buffer
ldy #0
- lda p8v_left,y
sta cx16.VERA_AUDIO_DATA
lda p8v_left+1,y
sta cx16.VERA_AUDIO_DATA
lda p8v_right,y
sta cx16.VERA_AUDIO_DATA
lda p8v_right+1,y
sta cx16.VERA_AUDIO_DATA
iny
iny
cpy #16
bne -
}}
}
}
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