-- 1. Read the value of 0x0051CE8C and store that on DC of Teran Marine. This DC holds the last time music is played.
for i = 30, 0, -1 do
   Trigger {
       players = {P8},
       conditions = {
           Switch("Switch 1", Cleared);
           Memory(0x0051CE8C, AtLeast, 2^i);
       },
       actions = {
           SetMemory(0x0051CE8C, Subtract, 2^i);
           SetDeaths(P8, Add, 2^i, "Terran Marine");
           SetDeaths(P8, Add, 2^i, "Terran Vulture");
       }
   }

for i in 30, 0, -1 do
   Trigger {
       players = {P8},
       conditions = {
           Switch("Switch 1", Cleared);
           Deaths(P8, AtLeast, 2^i, "Terran Vulture");
       },
       actions = {
           SetMemory(0x0051CE8C, Add, 2^i);
           SetDeaths(P8, Subtract, 2^i, "Terran Vulture");
       }
   }

-- 2. Play the music.
Trigger {
   players = {P8},
   conditions = {
       Always();
   },
   actions = {
       SetSwitch("Switch 1", Set);
       PlayWAV("[path to bgm here]");
   }
}


-- 3. With preserve trigger:
--     3-1. Read the value of 0x0051CE8C and store that on DC of Terran Firebat.
for i = 30, 0, -1 do
   Trigger {
       players = {P8},
       conditions = {
           Memory(0x0051CE8C, AtLeast, 2^i);
       },
       actions = {
           SetMemory(0x0051CE8C, Subtract, 2^i);
           SetDeaths(P8, Add, 2^i, "Terran Firebat");
           SetDeaths(P8, Add, 2^i, "Terran Vulture");
           PreserveTrigger();
       }
   }

for i in 30, 0, -1 do
   Trigger {
       players = {P8},
       conditions = {
           Deaths(P8, AtLeast, 2^i, "Terran Vulture");
       },
       actions = {
           SetMemory(0x0051CE8C, Add, 2^i);
           SetDeaths(P8, Subtract, 2^i, "Terran Vulture");
           PreserveTrigger();
       }
   }

--     3-2. Compare that value with DC of Terran Marine.
for i = 30, 0, -1 do
   Trigger {
       players = {P8},
       conditions = {
           Deaths(P8, AtLeast, 2^i, "Terran Firebat");
       },
       actions = {
           SetDeaths(P8, Subtract, 2^i, "Terran Firebat");
           SetDeaths(P8, Subtract, 2^i, "Terran Marine");
           SetDeaths(P8, Add, 2^i, "Terran Vulture");
           PreserveTrigger();
       }
   }

--     3-3. If the difference is larger or equal to the length of the music in milliseconds:
--         3-3-2. Play the music again.
Trigger {
   players = {P8},
   conditions = {
       Deaths(P8, AtLeast, (length of bgm here), "Terran Marine");
   },
   actions = {
       SetSwitch("Switch 2", Set);
       SetDeaths(P8, SetTo, 0, "Terran Marine");
       PlayWAV("[path to bgm here]");
       PreserveTrigger();
   }
}

--         3-3-1. Copy DC of Terran Firebat (currently in vulture) to DC of Terran Marine.
-- If condition is not met, revert DC of Terran Marine
for i in 30, 0, -1 do
   Trigger {
       players = {P8},
       conditions = {
           Deaths(P8, AtLeast, 2^i, "Terran Vulture");
       },
       actions = {
           SetDeaths(P8, Subtract, 2^i, "Terran Vulture");
           SetDeaths(P8, Add, 2^i, "Terran Marine");
           PreserveTrigger();
       }
   }

--  Reset switch 2
Trigger {
   players = {P8},
   conditions = {
       Always();
   },
   actions = {
       SetSwitch("Switch 2", Clear);
   }
}

var bgmTimer;

function time() {
   return -dwread_epd(EPD(0x0051CE8C));
}

// Code on onPluginstart is executed only once, at the start of the game.
function onPluginStart() {
   bgmTimer = time();
   PlayWAV([path of bgm here]);
}

/// Code on afterPluginStart is executed every trigger loop
function afterPluginstart() {
   const currentTime = time();
   if(currentTime - bgmTimer > [length of bgm in millisecond here]) {
       bgmTimer = currentTime;
       PlayWAV([path of bgm here]);
   }
}