(local byte string.char)
(fn word->byte [x]
	"convert a 32 bit word into a little endian byte string"
	(string.char
		(-> x (band 0xff))
		(-> x (rshift 8) (band 0xff))
		(-> x (rshift 16) (band 0xff))
		(-> x (rshift 24))))
(fn half->byte [x]
	"convert a 16 bit half-word into a little endian byte string"
	(string.char
		(-> x (band 0xff))
		(-> x (rshift 8) (band 0xff))))

(local magic
			 (.. 
				 (byte 0x7f)
				 :ELF))
(local abi {:sysv 0})
(local isa {:arm32 0x28})
(local file-type {:executable 0x2})

(fn header [{:entry-point entry-point
					:phead-offset phead-offset
					:phead-count phead-count
					:section-header-offset shead-offset
					:section-header-count shead-count
					:string-section-index string-section-index
					:flags flags}]
	(let [phead-offset (or phead-offset 0x34)
										 flags (or flags 0)]
		(.. magic
				; 32 bit
				(byte 1)
				; little endian
				(byte 1)
				; version
				(byte 1)
				(byte (. abi :sysv))
				;abi version -- ignored
				(byte 0)
				; padding
				(byte 0 0 0)
				(word->byte 0)
				(half->byte (. file-type :executable))
				(half->byte (. isa :arm32))
				; version again
				(word->byte 1)
				(word->byte entry-point)
				(word->byte phead-offset)
				(word->byte shead-offset)
				(word->byte flags)
				; structure size	
				(half->byte 0x34)
				; program header size
				(half->byte 0x20)
				(half->byte phead-count)
				; section header size
				(half->byte 0x28)
				(half->byte shead-count)
				(half->byte string-section-index))))

(fn program-header [{}])

(local elf
	(header {:entry-point 0x8000
					:section-header-offset 0x100
					:section-header-count 0
					:string-section-index 0
					:phead-count 0}))