sound: fix ym2612 forgetting lfo state when dac is on

for less bad audio in OD2
notaz · Jun 16, 2023 · 76e87f9 · 76e87f9
1 parent 8013663
commit 76e87f9
Showing 1 changed file with 8 additions and 6 deletions.
diff --git a/pico/sound/ym2612.c b/pico/sound/ym2612.c
@@ -892,7 +892,8 @@ typedef struct
 	UINT16 vol_out2;
 	UINT16 vol_out3;
 	UINT16 vol_out4;
-	UINT32 pad[2];
+	UINT32 lfo_init_sft16;
+	UINT32 pad;
 	UINT32 phase1;   /* 10 */
 	UINT32 phase2;
 	UINT32 phase3;
@@ -1225,18 +1226,18 @@ static chan_rend_context crct;
 static void chan_render_prep(void)
 {
 	crct.eg_timer_add = ym2612.OPN.eg_timer_add;
+	crct.lfo_init_sft16 = g_lfo_ampm << 16;
 	crct.lfo_inc = ym2612.OPN.lfo_inc;
 }
 
-static void chan_render_finish(s32 *buffer, unsigned short length, int active_chans)
+static void chan_render_finish(s32 *buffer, int length, int active_chans)
 {
 	ym2612.OPN.eg_cnt = crct.eg_cnt;
 	ym2612.OPN.eg_timer = crct.eg_timer;
-	g_lfo_ampm = crct.pack >> 16; // need_save
-	ym2612.OPN.lfo_cnt = crct.lfo_cnt;
+	ym2612.OPN.lfo_cnt += ym2612.OPN.lfo_inc * length;
 }
 
-static UINT32 update_lfo_phase(FM_SLOT *SLOT, UINT32 block_fnum)
+static UINT32 update_lfo_phase(const FM_SLOT *SLOT, UINT32 block_fnum)
 {
 	UINT32 fnum_lfo;
 	INT32  lfo_fn_table_index_offset;
@@ -1273,7 +1274,7 @@ static int chan_render(s32 *buffer, int length, int c, UINT32 flags) // flags: s
 
 	if (crct.lfo_inc) {
 		flags |= 8;
-		flags |= g_lfo_ampm << 16;
+		flags |= crct.lfo_init_sft16;
 		flags |= crct.CH->AMmasks << 8;
 		if (crct.CH->ams == 8) // no ams
 		     flags &= ~0xf00;
@@ -1809,6 +1810,7 @@ int YM2612UpdateOne_(s32 *buffer, int length, int stereo, int is_buf_empty)
 	if (ym2612.slot_mask & 0x00f000) active_chs |= chan_render(buffer, length, 3, flags|((pan&0x0c0)>>2)) << 3;
 	BIT_IF(flags, 1, (ym2612.ssg_mask & 0x0f0000) && (ym2612.OPN.ST.flags & 1));
 	if (ym2612.slot_mask & 0x0f0000) active_chs |= chan_render(buffer, length, 4, flags|((pan&0x300)>>4)) << 4;
+	g_lfo_ampm = crct.pack >> 16; // need_save; now because ch5 might skip updating it
 	BIT_IF(flags, 1, (ym2612.ssg_mask & 0xf00000) && (ym2612.OPN.ST.flags & 1));
 	if (ym2612.slot_mask & 0xf00000) active_chs |= chan_render(buffer, length, 5, flags|((pan&0xc00)>>6)|(!!ym2612.dacen<<2)) << 5;
 #undef	BIT_IF