Skip to navigation

⌂ ∞ Elite on the BBC Micro and NES

Text: TT41

[NES version, Bank 2]

       Name: TT41                                                    [Show more]
       Type: Subroutine
   Category: Text
    Summary: Print a letter according to Sentence Case

    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * TT27 calls TT41




 The rules for printing in Sentence Case are as follows:

   * If QQ17 bit 6 is set, print lower case (via TT45)

   * If QQ17 bit 6 is clear, then:

       * If character is punctuation, just print it

       * If character is a letter, set QQ17 bit 6 and print letter as a capital



 Arguments:

   A                    The character to be printed. Can be one of the
                        following:

                          * 7 (beep)

                          * 10-13 (line feeds and carriage returns)

                          * 32-95 (ASCII capital letters, numbers and
                            punctuation)

   X                    Contains the current value of QQ17

   QQ17                 Bit 7 is set



.TT41

                        ; If we get here, then QQ17 has bit 7 set, so we are in
                        ; Sentence Case

 BIT QQ17               ; If QQ17 also has bit 6 set, jump to TT45 to print
 BVS TT45               ; this character in lower case

                        ; If we get here, then QQ17 has bit 6 clear and bit 7
                        ; set, so we are in Sentence Case and we need to print
                        ; the next letter in upper case

 JMP DASC               ; Jump to DASC to print the character in A