assign04/types.h at master · cmsc430/assign04 · GitHub

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/*
  Bit layout of values

  Values are either:
  - Integers:   end in  #b0
  - Characters: end in #b01
  - True:              #b11
  - False:            #b111
  - Eof:             #b1011
  - Void:            #b1111
*/
#define int_shift        1
#define int_type_mask    ((1 << int_shift) - 1)
#define int_type_tag     (0 << (int_shift - 1))
#define nonint_type_tag  (1 << (int_shift - 1))
#define char_shift       (int_shift + 1)
#define char_type_mask   ((1 << char_shift) - 1)
#define char_type_tag    ((0 << (char_shift - 1)) | nonint_type_tag)
#define nonchar_type_tag ((1 << (char_shift - 1)) | nonint_type_tag)
#define val_true  ((0 << char_shift) | nonchar_type_tag)
#define val_false ((1 << char_shift) | nonchar_type_tag)
#define val_eof   ((2 << char_shift) | nonchar_type_tag)
#define val_void  ((3 << char_shift) | nonchar_type_tag)