basic assembler that emmits a EXE file

assembler.rb

@@ -0,0 +1,83 @@
+
+$bytes = []
+
+def zero_fill(pos)
+	while ($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
+
+
+
+
+
+
+