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tiny psg improvement to avoid clicks more on changing freq or envelope, added cx16.vpoke_mask()

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Irmen de Jong 2023-04-26 17:22:27 +02:00
parent cd8e7f3912
commit e1b89494d0
2 changed files with 31 additions and 13 deletions
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25
compiler/res/prog8lib/cx16/psg.p8
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@ -22,6 +22,7 @@ psg {
; waveform = one of PULSE,SAWTOOTH,TRIANGLE,NOISE.
; pulsewidth = 0-63. Specifies the pulse width for waveform=PULSE.
envelope_states[voice_num] = 255
sys.set_irqd()
cx16.r0 = $f9c2 + voice_num * 4
cx16.VERA_CTRL = 0
cx16.VERA_ADDR_L = lsb(cx16.r0)
@ -32,6 +33,7 @@ psg {
cx16.VERA_DATA0 = waveform | pulsewidth
envelope_volumes[voice_num] = mkword(volume, 0)
envelope_maxvolumes[voice_num] = volume
sys.clear_irqd()
}
; sub freq_hz(ubyte voice_num, float hertz) {
@ -45,30 +47,31 @@ psg {
; -- Changes the frequency of the voice's sound.
; voice_num = 0-15, vera_freq = 0-65535 calculate this via the formula given in the Vera's PSG documentation.
; (https://github.com/x16community/x16-docs/blob/master/VERA%20Programmer's%20Reference.md)
cx16.r0 = $f9c0 + voice_num * 4
; Write freq MSB first and then LSB to reduce the chance on clicks
sys.set_irqd()
cx16.r0 = $f9c1 + voice_num * 4
cx16.VERA_CTRL = 0
cx16.VERA_ADDR_L = lsb(cx16.r0)
cx16.VERA_ADDR_M = msb(cx16.r0)
cx16.VERA_ADDR_H = 1
cx16.VERA_DATA0 = lsb(vera_freq)
cx16.VERA_ADDR_L++
cx16.VERA_DATA0 = msb(vera_freq)
cx16.VERA_ADDR_L--
cx16.VERA_DATA0 = lsb(vera_freq)
sys.clear_irqd()
}
sub volume(ubyte voice_num, ubyte vol) {
; -- Modifies the volume of this voice.
; voice_num = 0-15, vol = 0-63 where 0=silent, 63=loudest.
cx16.r0 = $f9c2 + voice_num * 4
cx16.vpoke(1, cx16.r0, cx16.vpeek(1, cx16.r0) & %11000000 | vol)
envelope_volumes[voice_num] = mkword(vol, 0)
cx16.vpoke_mask(1, $f9c2 + voice_num * 4, %11000000, vol)
envelope_maxvolumes[voice_num] = vol
}
sub pulse_width(ubyte voice_num, ubyte pw) {
; -- Modifies the pulse width of this voice (when waveform=PULSE)
; voice_num = 0-15, pw = 0-63 where 0=narrow, 63=50%cycle so square wave.
cx16.r0 = $f9c3 + voice_num * 4
cx16.vpoke(1, cx16.r0, cx16.vpeek(1, cx16.r0) & %11000000 | pw)
cx16.vpoke_mask(1, $f9c3 + voice_num * 4, %11000000, pw)
}
sub envelope(ubyte voice_num, ubyte maxvolume, ubyte attack, ubyte sustain, ubyte release) {
@ -84,11 +87,8 @@ psg {
envelope_attacks[voice_num] = attack
envelope_sustains[voice_num] = sustain
envelope_releases[voice_num] = release
if attack
attack = 0
else
attack = maxvolume ; max volume when no attack is set
envelope_volumes[voice_num] = mkword(attack, 0)
if maxvolume<envelope_volumes[voice_num]
envelope_volumes[voice_num] = maxvolume
envelope_maxvolumes[voice_num] = maxvolume
envelope_states[voice_num] = 0
}
@ -97,7 +97,6 @@ psg {
; -- Shut down all PSG voices.
for cx16.r1L in 0 to 15 {
envelope_states[cx16.r1L] = 255
envelope_volumes[cx16.r1L] = 0
volume(cx16.r1L, 0)
}
}

19
compiler/res/prog8lib/cx16/syslib.p8
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@ -604,6 +604,25 @@ asmsub vpoke_xor(ubyte bank @A, uword address @R0, ubyte value @Y) clobbers (A)
}}
}
asmsub vpoke_mask(ubyte bank @A, uword address @R0, ubyte mask @X, ubyte value @Y) clobbers (A) {
; -- bitwise or a single byte to the value already in the VERA's video memory at that location
; after applying the and-mask. Note: inefficient when writing multiple sequential bytes!
%asm {{
sty P8ZP_SCRATCH_B1
stz cx16.VERA_CTRL
and #1
sta cx16.VERA_ADDR_H
lda cx16.r0
sta cx16.VERA_ADDR_L
lda cx16.r0+1
sta cx16.VERA_ADDR_M
txa
and cx16.VERA_DATA0
ora P8ZP_SCRATCH_B1
sta cx16.VERA_DATA0
rts
}}
}
; ---- system stuff -----
asmsub init_system() {