music fw

2026-07-14 08:51:00 +02:00
parent 545e9153f2
commit 3714247dc2
3 changed files with 118 additions and 0 deletions
@@ -0,0 +1,83 @@
+; -----------------------------------------------------------
+; music.asm - SID music driver skeleton
+;   called once per frame from wait_frame
+;   music_init: clear SID registers
+;   music_play: placeholder (currently silent)
+;   music_mute / music_unmute: volume control
+;
+;   To add music: replace music_play with a real SID player
+;   routine (e.g. GoatTracker export), or write patterns into
+;   this file using the SID register definitions below.
+; -----------------------------------------------------------
+
+; ---- SID registers ----
+SID_BASE = $d400
+
+SID_V1_FL = SID_BASE+0          ; voice 1 frequency low
+SID_V1_FH = SID_BASE+1          ; voice 1 frequency high
+SID_V1_PL = SID_BASE+2          ; voice 1 pulse width low
+SID_V1_PH = SID_BASE+3          ; voice 1 pulse width high
+SID_V1_CR = SID_BASE+4          ; voice 1 control (gate, waveform)
+SID_V1_AD = SID_BASE+5          ; voice 1 attack/decay
+SID_V1_SR = SID_BASE+6          ; voice 1 sustain/release
+
+SID_V2_FL = SID_BASE+7          ; voice 2 frequency low
+SID_V2_FH = SID_BASE+8          ; voice 2 frequency high
+SID_V2_PL = SID_BASE+9          ; voice 2 pulse width low
+SID_V2_PH = SID_BASE+10         ; voice 2 pulse width high
+SID_V2_CR = SID_BASE+11         ; voice 2 control
+SID_V2_AD = SID_BASE+12         ; voice 2 attack/decay
+SID_V2_SR = SID_BASE+13         ; voice 2 sustain/release
+
+SID_V3_FL = SID_BASE+14         ; voice 3 frequency low
+SID_V3_FH = SID_BASE+15         ; voice 3 frequency high
+SID_V3_PL = SID_BASE+16         ; voice 3 pulse width low
+SID_V3_PH = SID_BASE+17         ; voice 3 pulse width high
+SID_V3_CR = SID_BASE+18         ; voice 3 control
+SID_V3_AD = SID_BASE+19         ; voice 3 attack/decay
+SID_V3_SR = SID_BASE+20         ; voice 3 sustain/release
+
+SID_FC_LO = SID_BASE+21         ; filter cutoff low (bits 0-2)
+SID_FC_HI = SID_BASE+22         ; filter cutoff high
+SID_FCTL  = SID_BASE+23         ; filter resonance + voice routing
+SID_VOL   = SID_BASE+24         ; filter mode (hi nibble) + master volume (lo nibble)
+
+; ---- initialize SID ----
+music_init:
+    ldx #24
+    lda #0
+mi_clr:
+    sta SID_BASE,x
+    dex
+    bpl mi_clr
+
+    lda #$0f                    ; master volume = 15
+    sta SID_VOL
+
+    lda #0
+    sta mus_muted
+    rts
+
+; ---- play one tick: called once per frame ----
+; Replace this with a real music player routine.
+music_play:
+    lda mus_muted
+    bne mp_silent
+    ; --- insert SID player call here ---
+mp_silent:
+    rts
+
+; ---- mute: silence SID ----
+music_mute:
+    lda #$00
+    sta SID_VOL
+    rts
+
+; ---- unmute: restore volume ----
+music_unmute:
+    lda #$0f
+    sta SID_VOL
+    rts
+
+; ---- state ----
+mus_muted:     !byte 0          ; 1 = muted