impostor music

defs.asm

@@ -52,7 +52,7 @@ RAS_BARTOP  = 16                 ; first raster line of the bar area (slide 3):
 BAR_STEPS   = 57                 ; 57 steps * 4 lines = up to line 244
 
 NUM_SLIDES  = 5
-SLIDE_TIME  = 300                ; 6 seconds per slide (PAL, 50 frames/s)
+SLIDE_TIME  = 400                ; 8 seconds per slide (PAL, 50 frames/s)
 S5_TIME     = 450                ; slide 5 is longer: the typewriter needs time
 FADE_STEPS  = 5                  ; fade steps (longest fadetbl chain is 4)
 FADE_SPEED  = 4                  ; frames between two fade steps

main.asm

@@ -51,6 +51,8 @@ start:
 ; ============================================================
 main:
     jsr call_update
+    jsr music_play       ; slide updates end at RAS_BOTTOM, so this
+                         ;   ticks the music once per frame
 
     ; 'p' toggles pause - edge detected, so holding the key
     ; does not keep flipping the state

music.asm

@@ -1,13 +1,18 @@
 ; -----------------------------------------------------------
-; music.asm - SID music driver skeleton
+; music.asm - SID music driver
 ;   called once per frame from wait_frame
-;   music_init: clear SID registers
+;   music_init: clear SID, set instruments, restart the song
-;   music_play: placeholder (currently silent)
+;   music_play: pattern player tick (once per frame)
 ;   music_mute / music_unmute: volume control
 ;
-;   To add music: replace music_play with a real SID player
+;   The tune is track 0 ("room work") of the Impostor TIC-80
-;   routine (e.g. GoatTracker export), or write patterns into
+;   cart, converted from inc/meta/meta.assets.lua:
-;   this file using the SID register definitions below.
+;     voice 1: bass line (sfx 59, soft sine -> SID triangle)
+;     voice 2: drums (sfx 61, TIC-80 noise -> SID noise,
+;              C-1 = kick, C-4 = snare)
+;   Original timing: tempo 150, speed 5 = 12 rows/s at 60 Hz.
+;   On PAL (50 Hz) that is 25 frames per 6 rows, so every
+;   sixth row lasts 5 frames instead of 4 (see spd_tbl).
 ; -----------------------------------------------------------
 
 ; ---- SID registers ----
@@ -42,7 +47,15 @@ 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 ----
+; ---- waveform control values ----
+BASS_ON   = $11                 ; triangle + gate
+BASS_OFF  = $10
+DRUM_ON   = $81                 ; noise + gate
+DRUM_OFF  = $80
+
+SONG_LEN  = 128                 ; 2 frames x 64 rows
+
+; ---- initialize SID and restart the song ----
 music_init:
     ldx #24
     lda #0
@@ -51,20 +64,97 @@ mi_clr:
     dex
     bpl mi_clr
 
+    lda #$00                    ; bass: instant attack, full sustain
+    sta SID_V1_AD
+    lda #$f4
+    sta SID_V1_SR
+    lda #$05                    ; drums: instant attack, ~170 ms decay
+    sta SID_V2_AD
+    lda #$00
+    sta SID_V2_SR
+
     lda #$0f                    ; master volume = 15
     sta SID_VOL
 
     lda #0
     sta mus_muted
+    sta mus_row
+    sta mus_spd_ix
+    lda #1                      ; first music_play tick starts row 0
+    sta mus_tick
     rts
 
 ; ---- play one tick: called once per frame ----
-; Replace this with a real music player routine.
 music_play:
     lda mus_muted
-    bne mp_silent
+    bne mp_done                 ; muted: song position frozen too
-    ; --- insert SID player call here ---
+    dec mus_tick
-mp_silent:
+    beq mp_row
+mp_done:
+    rts
+
+mp_row:
+    ldx mus_spd_ix              ; reload row length (4,4,4,4,4,5 frames)
+    lda spd_tbl,x
+    sta mus_tick
+    inx
+    cpx #6
+    bne mp_spd_ok
+    ldx #0
+mp_spd_ok:
+    stx mus_spd_ix
+
+    ldx mus_row
+
+    ; ---- voice 1: bass ----
+    lda bass_pat,x
+    beq mp_drums                ; 0 = no event
+    cmp #1
+    bne mp_bass_note
+    lda #BASS_OFF               ; 1 = key off
+    sta SID_V1_CR
+    jmp mp_drums
+mp_bass_note:
+    and #$7f                    ; $80|n = trigger note n
+    tay
+    lda bass_flo,y
+    sta SID_V1_FL
+    lda bass_fhi,y
+    sta SID_V1_FH
+    lda #BASS_OFF               ; gate off + on restarts the envelope
+    sta SID_V1_CR
+    lda #BASS_ON
+    sta SID_V1_CR
+
+    ; ---- voice 2: drums ----
+mp_drums:
+    lda drum_pat,x
+    beq mp_next
+    cmp #1
+    bne mp_drum_note
+    lda #DRUM_OFF
+    sta SID_V2_CR
+    jmp mp_next
+mp_drum_note:
+    and #$7f
+    tay
+    lda drum_flo,y
+    sta SID_V2_FL
+    lda drum_fhi,y
+    sta SID_V2_FH
+    lda #DRUM_OFF
+    sta SID_V2_CR
+    lda #DRUM_ON
+    sta SID_V2_CR
+
+mp_next:
+    inx
+    cpx #SONG_LEN
+    bne mp_store
+    ldx #0                      ; loop the song
+    stx mus_spd_ix              ; restart the 4,4,4,4,4,5 cycle with it
+mp_store:
+    stx mus_row
     rts
 
 ; ---- mute: silence SID ----
@@ -81,3 +171,38 @@ music_unmute:
 
 ; ---- state ----
 mus_muted:     !byte 0          ; 1 = muted
+mus_row:       !byte 0          ; song position (0..SONG_LEN-1)
+mus_tick:      !byte 1          ; frames left of the current row
+mus_spd_ix:    !byte 0          ; index into spd_tbl
+
+spd_tbl:       !byte 4,4,4,4,4,5    ; 25 frames / 6 rows = 12 rows/s
+
+; ---- note tables (PAL SID: reg = Hz * 16777216 / 985248) ----
+; bass: 0 = C-2, 1 = A#1, 2 = D#2, 3 = F-2
+bass_flo: !byte $5a,$e0,$2d,$cf
+bass_fhi: !byte $04,$03,$05,$05
+; drums: noise pitch from the TIC-80 note (x32 waveform steps)
+;        0 = C-1 kick (low rumble), 1 = C-4 snare (bright)
+drum_flo: !byte $9c,$ff
+drum_fhi: !byte $45,$ff
+
+; ---- pattern data: one byte per row per voice ----
+;   $00 = nothing, $01 = key off, $80|n = play note n
+bass_pat:
+    !byte $80,$00,$00,$00,$01,$00,$80,$00,$01,$00,$00,$00,$81,$00,$80,$00
+    !byte $01,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
+    !byte $80,$00,$00,$00,$01,$00,$80,$00,$01,$00,$00,$00,$81,$00,$80,$00
+    !byte $01,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
+    !byte $80,$00,$00,$00,$01,$00,$80,$00,$01,$00,$00,$00,$81,$00,$80,$00
+    !byte $01,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
+    !byte $82,$00,$82,$00,$01,$00,$82,$00,$01,$00,$00,$00,$82,$00,$83,$00
+    !byte $01,$00,$83,$00,$01,$00,$83,$00,$83,$00,$01,$00,$83,$00,$01,$00
+drum_pat:
+    !byte $80,$00,$00,$00,$00,$00,$00,$00,$81,$00,$00,$00,$00,$00,$00,$00
+    !byte $80,$00,$00,$00,$00,$00,$80,$00,$81,$00,$00,$00,$00,$00,$00,$00
+    !byte $80,$00,$00,$00,$00,$00,$00,$00,$81,$00,$00,$00,$00,$00,$00,$00
+    !byte $80,$00,$00,$00,$00,$00,$80,$00,$81,$00,$00,$00,$00,$00,$00,$00
+    !byte $80,$00,$00,$00,$00,$00,$00,$00,$81,$00,$00,$00,$00,$00,$00,$00
+    !byte $80,$00,$00,$00,$00,$00,$80,$00,$81,$00,$00,$00,$00,$00,$00,$00
+    !byte $80,$00,$00,$00,$00,$00,$00,$00,$81,$00,$00,$00,$00,$00,$00,$00
+    !byte $80,$00,$00,$00,$00,$00,$80,$00,$81,$00,$00,$00,$00,$00,$00,$00