test_extsbx_1:
  #_ REGISTER_IN r4 0x000000000000007F
  extsb. r3, r4
  blr
  #_ REGISTER_OUT r3 0x000000000000007F
  #_ REGISTER_OUT r4 0x000000000000007F

test_extsbx_2:
  #_ REGISTER_IN r4 0x0000000000000080
  extsb. r3, r4
  blr
  #_ REGISTER_OUT r3 0xFFFFFFFFFFFFFF80
  #_ REGISTER_OUT r4 0x0000000000000080

test_extsbx_3:
  #_ REGISTER_IN r4 0x00000000000000FF
  extsb. r3, r4
  blr
  #_ REGISTER_OUT r3 0xFFFFFFFFFFFFFFFF
  #_ REGISTER_OUT r4 0x00000000000000FF

test_extsbx_4:
  #_ REGISTER_IN r4 0x0000000000000001
  extsb. r3, r4
  blr
  #_ REGISTER_OUT r3 0x0000000000000001
  #_ REGISTER_OUT r4 0x0000000000000001
