From f47de34e1618f75eeb34ab0fba6eca338b3e5d22 Mon Sep 17 00:00:00 2001
From: "Matthew D. Steele" <mdsteele@alum.mit.edu>
Date: Tue, 17 Sep 2024 10:39:37 -0400
Subject: [PATCH] Exclude eMusic::Silence from NSF file

---
 nsf/nsf.asm   | 7 +++++--
 src/audio.asm | 3 ++-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/nsf/nsf.asm b/nsf/nsf.asm
index efe45c7f..bb2280c7 100644
--- a/nsf/nsf.asm
+++ b/nsf/nsf.asm
@@ -29,7 +29,7 @@
 ;;;=========================================================================;;;
 
 kVersion       = 1      ; version number; 1 = NSF, 2 = NSF2
-kNumSongs      = eMusic::NUM_VALUES
+kNumSongs      = eMusic::NUM_VALUES - 1  ; (exclude eMusic::Silence)
 kFirstSong     = 1
 kDataLoadAddr  = $8000
 kDataInitAddr  = Func_NsfInit
@@ -89,7 +89,10 @@ kSoundChip     = 0      ; 0 = no extra sound chips
     pha  ; song number
     jsr Func_AudioReset
     pla  ; song number
-    sta Zp_Next_sAudioCtrl + sAudioCtrl::Music_eMusic
+    tay  ; song number
+    .assert eMusic::Silence = 0, error
+    iny
+    sty Zp_Next_sAudioCtrl + sAudioCtrl::Music_eMusic
     lda #$ff
     sta Zp_Next_sAudioCtrl + sAudioCtrl::Enable_bool
     sta Zp_Next_sAudioCtrl + sAudioCtrl::MasterVolume_u8
diff --git a/src/audio.asm b/src/audio.asm
index b01a422c..6ed82ad1 100644
--- a/src/audio.asm
+++ b/src/audio.asm
@@ -168,7 +168,8 @@ Ram_Sound_sChanSfx_arr: .res .sizeof(sChanSfx) * kNumApuChannels
     sta Zp_AudioEnabled_bool
     sta Zp_MusicFlag_bMusic
 _HaltMusic:
-    ldx #eMusic::Silence  ; param: eMusic to play
+    .assert eMusic::Silence = 0, error
+    tax  ; param: eMusic to play (A is zero, so this is eMusic::Silence)
     jsr Func_AudioRestartMusic
 _HaltSfx:
     lda #0