To conform to Windows's real mapping, cp932 codec maps the following
codepoints in addition of the official cp932 mapping.

  CP932     Unicode     Description

  0x80      0x80        UNDEFINED
  0xA0      0xF8F0      UNDEFINED
  0xFD      0xF8F1      UNDEFINED
  0xFE      0xF8F2      UNDEFINED
  0xFF      0xF8F3      UNDEFINED

