The PrintDigit subroutine - The Sentinel on the BBC Micro

       Name: PrintDigit                                              [Show more]
       Type: Subroutine
   Category: Text
    Summary: Print a numerical digit, printing zero as a capital "O"
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * PrintInputBuffer calls PrintDigit


 Arguments:

   A                    The numerical digit to be printed as an ASCII code


.PrintDigit

 CMP #'0'               \ If the character in A is not a zero, jump to zero1 to
 BNE zero1              \ skip the following

 LDA #'O'               \ The character in A is a zero, so set A to ASCII "O" so
                        \ we print zero as capital "O" instead

.zero1

 BIT printTextIn3D      \ If bit 7 of printTextIn3D is set then we are printing
 BMI SpawnCharacter3D   \ 3D text, so jump to SpawnCharacter3D to spawn the
                        \ character in 3D text blocks

 JMP PrintCharacter     \ Otherwise jump to PrintCharacter to print the single-
                        \ byte VDU command or character in A, returning from the
                        \ subroutine using a tail call

[X]

Subroutine PrintCharacter (category: Text)

Print a single-byte VDU command or character from a text token, optionally printing a drop shadow if the character is alphanumeric

[X]

Subroutine SpawnCharacter3D (Part 1 of 2) (category: Title screen)

Spawn a character on the landscape in large 3D blocks for drawing on the main title screen or secret code screen

[X]

Variable printTextIn3D in workspace Main variable workspace

Controls whether we are printing text normally or in 3D (as in the game's title on the title screen)

[X]

Label zero1 is local to this routine

Text: PrintDigit