From 3714247dc29ced8a50a5561f164c935a3634855b Mon Sep 17 00:00:00 2001
From: Zsolt Tasnadi <zsolt.tasnadi@zenheads.hu>
Date: Tue, 14 Jul 2026 08:51:00 +0200
Subject: [PATCH] music fw

---
 main.asm        | 34 ++++++++++++++++++++
 music.asm       | 83 +++++++++++++++++++++++++++++++++++++++++++++++++
 transitions.asm |  1 +
 3 files changed, 118 insertions(+)
 create mode 100644 music.asm

diff --git a/main.asm b/main.asm
index 8fc306a..3b120fe 100644
--- a/main.asm
+++ b/main.asm
@@ -38,6 +38,8 @@
 start:
     sei                  ; no KERNAL IRQ - raster polling must not jitter
 
+    jsr music_init       ; set up SID and start the music
+
     lda #0
     sta framectr
     sta slide
@@ -73,6 +75,19 @@ p_done:
     sta COLRAM+39
 no_pdraw:
 
+    jsr scan_m           ; 'm' toggles mute - edge detected
+    bne m_up
+    lda mheld
+    bne m_done
+    lda #1
+    sta mheld
+    jsr toggle_mute
+    jmp m_done
+m_up:
+    lda #0
+    sta mheld
+m_done:
+
     jsr scan_del         ; backspace: one slide back
     beq go_back
 
@@ -157,6 +172,23 @@ scan_del:                ; inst/del: column 0, row 0
     ldy #$01
     jmp scan_key
 
+scan_m:                  ; 'm': column 4, row 4
+    lda #$ef
+    ldy #$10
+    jmp scan_key
+
+; ---- flip the mute state ----
+toggle_mute:
+    lda mus_muted
+    eor #1
+    sta mus_muted
+    bne tm_off
+    jsr music_unmute     ; was muted, now unmute
+    rts
+tm_off:
+    jsr music_mute       ; was playing, now mute
+    rts
+
 call_update:
     jmp (updvec)         ; each update runs exactly one frame, ends with rts
 
@@ -191,6 +223,7 @@ slide_setup:
 !src "slide3.asm"
 !src "slide4.asm"
 !src "slide5.asm"
+!src "music.asm"
 
 ; ---- slide table: init vector, update vector, duration ----
 slide_init_lo:
@@ -218,3 +251,4 @@ durlo:     !byte 0       ; frames left on this slide (16 bit)
 durhi:     !byte 0
 paused:    !byte 0       ; 1 = slide countdown frozen
 pheld:     !byte 0       ; 'p' key edge detection state
+mheld:     !byte 0       ; 'm' key edge detection state
diff --git a/music.asm b/music.asm
new file mode 100644
index 0000000..d82a1b6
--- /dev/null
+++ b/music.asm
@@ -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
diff --git a/transitions.asm b/transitions.asm
index e6d7bf1..f9cb758 100644
--- a/transitions.asm
+++ b/transitions.asm
@@ -334,6 +334,7 @@ wf_reach:
     lda RASTER
     cmp #RAS_BOTTOM
     bne wf_reach
+    jsr music_play       ; advance the music once per frame
     rts
 
 ; ---- copy color RAM to FADEBUF, then blacken color RAM ----