type
  InterruptFrame = ptr object
    ip: uint
    cs: uint
    flags: uint
    sp: uint
    ss: uint

# http://clang.llvm.org/docs/AttributeReference.html#interrupt-avr
proc interrupt_handler(frame: InterruptFrame) {.exportc, codegenDecl: "__attribute__((interrupt)) $# $#$#".} =
  discard