Text: TT42

       Name: TT42                                                    [Show more]
       Type: Subroutine
   Category: Text
    Summary: Print a letter in lower case
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * TT45 calls TT42
             * TT41 calls via TT44


 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)


 Other entry points:

   TT44                 Jumps to TT26 to print the character in A (used to
                        enable us to use a branch instruction to jump to TT26)


.TT42

 CMP #'A'               ; If A < ASCII "A", then this is punctuation, so jump
 BCC TT44               ; to TT26 (via TT44) to print the character as is, as
                        ; we don't care about the character's case

 CMP #'Z'+1             ; If A >= (ASCII "Z" + 1), then this is also
 BCS TT44               ; punctuation, so jump to TT26 (via TT44) to print the
                        ; character as is, as we don't care about the
                        ; character's case

 ADC #32                ; Add 32 to the character, to convert it from upper to
                        ; lower case

.TT44

 JMP TT26               ; Print the character in A