Text: PrintCtrlCode

       Name: PrintCtrlCode                                           [Show more]
       Type: Subroutine
   Category: Text
    Summary: Print a control code (in the range 0 to 9)
  Deep dive: Multi-language support in NES Elite
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * PrintCtrlCode_b0 calls PrintCtrlCode


.PrintCtrlCode

 TXA                    ; Copy the token number from X to A. We can then keep
                        ; decrementing X and testing it against zero, while
                        ; keeping the original token number intact in A; this
                        ; effectively implements a switch statement on the
                        ; value of the token

 BEQ csh                ; If token = 0, this is control code 0 (current amount
                        ; of cash and newline), so jump to csh to print the
                        ; amount of cash and return from the subroutine using
                        ; a tail call

 DEX                    ; If token = 1, this is control code 1 (current galaxy
 BEQ tals               ; number), so jump to tal via tals to print the galaxy
                        ; number and return from the subroutine using a tail
                        ; call

 DEX                    ; If token = 2, this is control code 2 (current system
 BEQ ypls               ; name), so jump to ypl via ypls to print the current
                        ; system name  and return from the subroutine using a
                        ; tail call

 DEX                    ; If token > 3, skip the following instruction
 BNE P%+5

 JMP cpl                ; This token is control code 3 (selected system name)
                        ; so jump to cpl to print the selected system name
                        ; and return from the subroutine using a tail call

 DEX                    ; If token <> 4, skip the following instruction
 BNE P%+5

 JMP cmn                ; This token is control code 4 (commander name) so jump
                        ; to cmn to print the commander name and return from the
                        ; subroutine using a tail call

 DEX                    ; If token = 5, this is control code 5 (fuel, newline,
 BEQ fwls               ; cash, newline), so jump to fwl via fwls to print the
                        ; fuel level and return from the subroutine using a tail
                        ; call

 DEX                    ; If token > 6, skip the following three instructions
 BNE ptok2

 LDA #%10000000         ; This token is control code 6 (switch to Sentence
 STA QQ17               ; Case), so set bit 7 of QQ17 to switch to Sentence Case

.ptok1

 RTS                    ; Return from the subroutine

.ptok2

 DEX                    ; If token = 7, this is control code 7 (beep), so jump
 BEQ ptok1              ; to ptok1 to return from the subroutine

 DEX                    ; If token > 8, jump to ptok3
 BNE ptok3

 STX QQ17               ; This is control code 8, so set QQ17 = 0 to switch to
                        ; ALL CAPS (we know X is zero as we just passed through
                        ; a BNE)

 RTS                    ; Return from the subroutine

.ptok3

                        ; If we get here then token > 8, so this is control code
                        ; 9 (print a colon then tab to column 22 or 23)

 JSR TT73               ; Print a colon

 LDA languageNumber     ; If bit 1 of languageNumber is set, then the chosen
 AND #%00000010         ; language is German, so jump to ptok4 to move the text
 BNE ptok4              ; cursor to column 23

 LDA #22                ; Bit 1 of languageNumber is clear, so the chosen
 STA XC                 ; language is English or French, so move the text cursor
                        ; to column 22

 RTS                    ; Return from the subroutine

.ptok4

 LDA #23                ; Move the text cursor to column 23
 STA XC

 RTS                    ; Return from the subroutine