aica/tima: slow TIMA interrupt from once every 1 counts to once every 3 counts

Makefile

@@ -1,6 +1,6 @@
 all: xm_player.elf
 
-OPT = -O2
+OPT = -O1
 
 MAKEFILE_PATH := $(patsubst %/,%,$(dir $(abspath $(firstword $(MAKEFILE_LIST)))))
 LIB ?= $(MAKEFILE_PATH)/dreamcast

src/interpreter.cpp

@@ -249,10 +249,12 @@ void interrupt()
       break;
     }
     */
-    if (state.channel[ch].keyon == 255) {
+    if (state.channel[ch].keyon > 128) {
-      wait(); aica_sound.channel[ch].KYONB(1);
       state.channel[ch].keyon -= 1;
     }
+    if (state.channel[ch].keyon == 128) {
+      wait(); aica_sound.channel[ch].KYONB(1);
+    }
   }
   wait(); aica_sound.channel[0].KYONEX(1);
 
@@ -261,7 +263,7 @@ void interrupt()
   }
   for (int ch = 0; ch < 64; ch++) {
     int keyon = state.channel[ch].keyon;
-    if (keyon != 255 && keyon != 0) {
+    if (keyon < 128 && keyon != 0) {
       state.channel[ch].keyon -= 1;
     }
   }
@@ -366,12 +368,12 @@ const int sample_data_length = (sizeof (sample_data));
 
 void deferred_load(int buf)
 {
-  state.deferred_load_tick = 44100 / 2;
+  const float aica_clock_multiplier = 44.1 / 3;
+
+  state.deferred_load_tick = aica_clock_multiplier * 1000 / 2;
 
   stop_sound();
 
-  const float aica_clock_multiplier = 44.1;
-
   state.sample_data_ix = xm_init(&interpreter::state.xm,
                                  buf,
                                  sample_data,

src/main.cpp

@@ -44,7 +44,7 @@ void vbr600()
     wait(); aica_sound.common.mcire = (1 << 6); // interrupt timer A
     wait(); aica_sound.common.tactl_tima =
         aica::tactl_tima::TACTL(0)  // increment once every sample
-      | aica::tactl_tima::TIMA(0xffff) // interrupt after 1 counts
+      | aica::tactl_tima::TIMA(0xfffd) // interrupt after 3 counts
       ;
 
     //scene::logo::sound::interrupt();
@@ -108,6 +108,7 @@ void main()
 
   system.IML6NRM = istnrm::end_of_render_tsp
                  | istnrm::v_blank_in
+                 | istnrm::end_of_transferring_punch_through_list
                  | istnrm::end_of_transferring_opaque_list;
 
   system.IML4EXT = istext::aica;

src/sound.cpp

@@ -131,7 +131,7 @@ void init()
 
   wait(); aica_sound.common.tactl_tima =
       aica::tactl_tima::TACTL(0)  // increment once every sample
-    | aica::tactl_tima::TIMA(0xffff) // interrupt after 1 counts
+    | aica::tactl_tima::TIMA(0xfffd) // interrupt after 3 counts
     ;
 
   wait(); aica_sound.common.mcieb = (1 << 6); // interrupt timer A