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- NOTES ON THE DISPLAY CHARACTER DATATYPE
- Cris Perdue
- 10/11/82
- File: PW:DISPLAY-CHAR.T
- -----------------------------------
- This module provides a set of macros for manipulating
- "display-character" objects. These objects are represented to
- LISP as integers, but are dealt with as a separate type of
- object.
- (DC-MAKE-ENHANCEMENT-MASK KEYWORD . . . ) Macro
- This macro generates a specific enhancement mask object. The
- keywords are unevaluated identifiers. At present, the possible
- keywords are INVERSE-VIDEO, BLINK, UNDERLINE, and INTENSIFY,
- which should be meaningful with respect to HP terminals.
- (DC-MAKE-FONT-MASK FONT-NUMBER) Macro
- This makes a font mask object, given a font number. Font numbers
- have no definition yet, because we have no fonts.
- (DISPLAY-CHARACTER-CONS ENHANCEMENT-MASK FONT-MASK CHAR-CODE) Macro
- This macro generates a display character object, given an
- enhancement mask, a font mask, and a character code. The mask
- objects' purpose in life is to be used as arguments to this
- function and to be compared against each other.
- (DC-ENHANCEMENT-MASK DC) Macro
- Extracts the enhancement mask from a display character.
- (DC-ENHANCEMENT-INDEX DC) Macro
- There are a finite number of different combinations of display
- enhancements that are possible for a display-character. This
- macro returns an integer in the range from 0 that uniquely
- identifies the combination of enhancements in effect for this
- display-character. There should probably be a symbolic constant
- giving the maximum value for the identifying integer. With N
- different enhancements, the value turns out to be 2 raised to the
- Nth power, minus 1.
- (DC-FONT-MASK DC) Macro
- Extracts the font mask from a display character.
- (DC-FONT-NUMBER DC) Macro
- Obtains the font number from a display character.
- (DC-CHARACTER-CODE DC) Macro
- Obtains the character code from a display character object.
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