71 lines
1.7 KiB
Fennel
71 lines
1.7 KiB
Fennel
(local byte string.char)
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(fn word->byte [x]
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"convert a 32 bit word into a little endian byte string"
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(string.char
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(-> x (band 0xff))
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(-> x (rshift 8) (band 0xff))
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(-> x (rshift 16) (band 0xff))
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(-> x (rshift 24))))
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(fn half->byte [x]
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"convert a 16 bit half-word into a little endian byte string"
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(string.char
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(-> x (band 0xff))
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(-> x (rshift 8) (band 0xff))))
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(local magic
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(..
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(byte 0x7f)
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:ELF))
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(local abi {:sysv 0})
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(local isa {:arm32 0x28})
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(local file-type {:executable 0x2})
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(fn header [{:entry-point entry-point
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:phead-offset phead-offset
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:phead-count phead-count
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:section-header-offset shead-offset
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:section-header-count shead-count
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:string-section-index string-section-index
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:flags flags}]
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(let [phead-offset (or phead-offset 0x34)
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flags (or flags 0)]
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(.. magic
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; 32 bit
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(byte 1)
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; little endian
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(byte 1)
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; version
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(byte 1)
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(byte (. abi :sysv))
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;abi version -- ignored
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(byte 0)
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; padding
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(byte 0 0 0)
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(word->byte 0)
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(half->byte (. file-type :executable))
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(half->byte (. isa :arm32))
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; version again
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(word->byte 1)
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(word->byte entry-point)
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(word->byte phead-offset)
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(word->byte shead-offset)
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(word->byte flags)
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; structure size
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(half->byte 0x34)
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; program header size
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(half->byte 0x20)
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(half->byte phead-count)
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; section header size
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(half->byte 0x28)
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(half->byte shead-count)
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(half->byte string-section-index))))
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(fn program-header [{}])
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(local elf
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(header {:entry-point 0x8000
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:section-header-offset 0x100
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:section-header-count 0
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:string-section-index 0
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:phead-count 0}))
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