$bytes = []

def zero_fill(pos)
	while ($bytes.length <= pos) do
		$bytes.push(0)
	end
end

def int(i)
	$bytes.push((i & 0x000000ff),
		(i & 0x0000ff00) >> 8,
		(i & 0x00ff0000) >> 16,
		(i & 0xff000000) >> 24)
end

def string(s)
	$bytes.push *s.bytes
	while (($bytes.length % 4) != 0) do
		$bytes.push 0
	end
end

def jmp(addr)
	# TODO: this probs wont show up since we have < 3mb of ram but
	# we can't jump to an address with a different 4 most significant bits
	raise "jmp addr must be 4 byte aligned" if addr % 4 != 0
	op = 0b0000_1000_0000_0000_0000_0000_0000_0000
	op = op | ((addr >> 2) & 0b11_11111111_11111111_11111111)
	int op
end

def jal(addr)
	# TODO: same problem as jmp
	raise "jmp addr must be 4 byte aligned" if addr % 4 != 0
	op = 0b0000_1100_0000_0000_0000_0000_0000_0000
	op = op | ((addr >> 2) & 0b11_11111111_11111111_11111111)
	int op
end

def nop
	int 0x00000000
end

$base_addr = 0x80010000 # 0x10000 # 0x80010000

string "PS-X EXE"
zero_fill 0x00f
int $base_addr # initial pc
int 0x00000000 # initial GP/R28
int $base_addr # destintation address in RAM
int 0x800 # file size excluding header (must be N * 0x800)
int 0x00000000 # Unknown/Unused
int 0x00000000 # Unknown/Unused
int 0x00000000 # Memfill start address
int 0x00000000 # Memfill size in bytes
int 0x801ffff0 # Initial SP/R29 & FP/R30 Base
int 0x00000000 # Initial SP/R29 & FP/R30 Offs
zero_fill 0x4b # Reserved for A(43h) Function
# Ascii marker would go here
zero_fill 0x7ff

# code
nop
nop
jal $base_addr
nop # nop (is always exec'd bc mips)

string "this is a test lol"
int 0xFFAAFFAA

zero_fill 0xfff

f = File.new "LOADTHIS.EXE", "wb"
f.write $bytes.pack("C*")
f.close