Text: StoreMessage

       Name: StoreMessage                                            [Show more]
       Type: Subroutine
   Category: Text
    Summary: Copy a message from the justified text buffer at BUF into the
             message buffer
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * mes9 calls StoreMessage
             * PrintMessage calls StoreMessage


.StoreMessage

 LDA #32                ; Set A = 32 - DTW5
 SEC                    ;
 SBC DTW5               ; Where DTW5 is the size of the justified text buffer at
                        ; BUF, so A contains the number of characters remaining
                        ; if we print the message buffer on one line (as each
                        ; line contains 32 characters)

 BCS smes1              ; If the subtraction didn't underflow, then the message
                        ; in the message buffer will fit on one line, so jump to
                        ; smes1 with the remaining number of characters in A

                        ; The subtraction underflowed, so the message will not
                        ; fit on one line
                        ;
                        ; In this case we just print as many characters as we
                        ; can and truncate the message at the end of the line

 LDA #31                ; Set the size of the message buffer in DTW5 to 31,
 STA DTW5               ; which is the maximum size of a one-line message

 LDA #2                 ; Set A = 2 so the message will be printed in column 1
                        ; on the left of the screen

.smes1

                        ; When we get here, A contains the number of characters
                        ; remaining if we were to print the message on one line
                        ; of the screen

 LSR A                  ; Set A = A / 2
                        ;
                        ; So A now contains half the amount of free space left
                        ; if we print the message on one line, which is the
                        ; amount of space on each side of the message when it is
                        ; centred on the line
                        ;
                        ; In other words, this is the column number where we
                        ; need to print our message for it to be centred
                        ; on-screen

 STA messXC             ; Store A in messXC, so when we erase the message via
                        ; the branch to me1 above, messXC will tell us where to
                        ; print it

 SETUP_PPU_FOR_ICON_BAR ; If the PPU has started drawing the icon bar, configure
                        ; the PPU to use nametable 0 and pattern table 0

 LDX DTW5               ; Set the size of the message in the message buffer to
 STX messageLength      ; the size of the justified text buffer, as we are about
                        ; to copy from one to the other

 INX                    ; Set X as a character counter so we can loop through
                        ; message and copy it one character at a time (we
                        ; increment it so X is at least 1, to make the following
                        ; loop work)

.smes2

 LDA BUF-1,X            ; Copy the character number X - 1 from BUF into
 STA messageBuffer-1,X  ; messageBuffer

 DEX                    ; Decrement the character counter

 BNE smes2              ; Loop back until we have copied all X characters

 STX de                 ; Zero de, the flag that appends " DESTROYED" to the
                        ; end of the next text token, so that it doesn't append
                        ; it to the next message

 SETUP_PPU_FOR_ICON_BAR ; If the PPU has started drawing the icon bar, configure
                        ; the PPU to use nametable 0 and pattern table 0

                        ; Fall through into DisableJustifyText to reset DTW4 and
                        ; DTW5 to turn off justified text and reset the
                        ; justified text buffer