Drawing the screen: clss

       Name: clss                                                    [Show more]
       Type: Subroutine
   Category: Drawing the screen
    Summary: Clear the screen, move the text cursor to the top-left corner and
             jump back into the CHPR routine to print the next character
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * CHPR calls clss


.clss

 BIT text               ; If bit 7 of text is clear then the current screen mode
 BPL clss1              ; is the high-resolution graphics mode, so jump to clss1
                        ; to clear the graphics screen

 JSR cleartext          ; This is a text view, so clear screen memory for the
                        ; text screen mode and move the text cursor to the
                        ; top-left corner

 LDA K3                 ; We called this routine from CHPR, which put the
                        ; character we are printing into K3, so set A to the
                        ; character number so we can jump back to CHPR to print
                        ; it on the newly cleared screen

 JMP RRafter            ; Jump back into the CHPR routine to print the character
                        ; in A

.clss1

 JSR cleargrap          ; This is a high-resolution graphics screen, so clear
                        ; screen memory for the top part of the graphics screen
                        ; mode (the space view), drawing blue borders along the
                        ; sides as we do so, and moving the text cursor to the
                        ; top-left corner

 LDA K3                 ; We called this routine from CHPR, which put the
                        ; character we are printing into K3, so set A to the
                        ; character number so we can jump back to CHPR to print
                        ; it on the newly cleared screen

 JMP RRafter            ; Jump back into the CHPR routine to print the character
                        ; in A