Changes due to code review.

[cc65] / libsrc / atari / cputc.s

diff --git a/libsrc/atari/cputc.s b/libsrc/atari/cputc.s
index 652c6589dd88c145b654629383ba09c2bb855e3c..5de39573c33181e2a637e9aa1cd4ad706beb55c3 100644 (file)
--- a/libsrc/atari/cputc.s
+++ b/libsrc/atari/cputc.s
@@ -1,86 +1,87 @@
 ;
-; Mark Keates, Christian Groessler
+; Mark Keates, Christian Groessler, Piotr Fusik
 ;
 ; void cputcxy (unsigned char x, unsigned char y, char c);
 ; void cputc (char c);
 ;
 
-       .export         _cputcxy, _cputc
-       .export         plot, cputdirect, putchar
-       .import         popa, _gotoxy, mul40
-       .importzp       tmp4,ptr4
-       .import         _revflag
+        .export         _cputcxy, _cputc
+        .export         plot, cputdirect, putchar
+        .import         gotoxy, __mul40
+        .importzp       tmp4,ptr4
+        .import         _revflag,setcursor
 
-       .include        "atari.inc"
+        .include        "atari.inc"
 
 _cputcxy:
-       pha                     ; Save C
-       jsr     popa            ; Get Y
-       jsr     _gotoxy         ; Set cursor, drop x
-       pla                     ; Restore C
+        pha                     ; Save C
+        jsr     gotoxy          ; Set cursor, drop x and y
+        pla                     ; Restore C
 
 _cputc:
-       cmp     #$0D            ; CR
-       bne     L4
-       lda     #0
-       sta     COLCRS
-       beq     plot            ; return
-       
-L4:    cmp     #$0A            ; LF
-       beq     newline
-       cmp     #ATEOL          ; Atari-EOL?
-       beq     newline
+        cmp     #$0D            ; CR
+        bne     L4
+        lda     #0
+        sta     COLCRS
+        beq     plot            ; return
 
-       tay
-       rol     a
-       rol     a
-       rol     a
-       rol     a
-       and     #3
-       tax
-       tya
-       and     #$9f
-       ora     ataint,x
+L4:     cmp     #$0A            ; LF
+        beq     newline
+        cmp     #ATEOL          ; Atari-EOL?
+        beq     newline
+
+        asl     a               ; shift out the inverse bit
+        adc     #$c0            ; grab the inverse bit; convert ATASCII to screen code
+        bpl     codeok          ; screen code ok?
+        eor     #$40            ; needs correction
+codeok: lsr     a               ; undo the shift
+        bcc     cputdirect
+        eor     #$80            ; restore the inverse bit
+
+cputdirect:                     ; accepts screen code
+        jsr     putchar
 
-cputdirect:                    ; accepts screen code
-       jsr     putchar
-       
 ; advance cursor
-       inc     COLCRS
-       lda     COLCRS
-       cmp     #40
-       bcc     plot
-       lda     #0
-       sta     COLCRS
+        inc     COLCRS
+        lda     COLCRS
+        cmp     #40
+        bcc     plot
+        lda     #0
+        sta     COLCRS
 
-       .export newline
+        .export newline
 newline:
-       inc     ROWCRS
-       lda     ROWCRS
-       cmp     #24
-       bne     plot
-       lda     #0
-       sta     ROWCRS
-plot:  ldy     COLCRS
-       ldx     ROWCRS
-       rts
+        inc     ROWCRS
+        lda     ROWCRS
+        cmp     #24
+        bne     plot
+        lda     #0
+        sta     ROWCRS
+plot:   jsr     setcursor
+        ldy     COLCRS
+        ldx     ROWCRS
+        rts
 
+; turn off cursor, update screen, turn on cursor
 putchar:
-       pha                     ; save char
-       lda     ROWCRS
-       jsr     mul40
-L3:    clc
-       adc     SAVMSC          ; add start of screen memory
-       sta     ptr4
-       lda     tmp4
-       adc     SAVMSC+1
-       sta     ptr4+1
-       pla                     ; get char again
-       ora     _revflag
-       ldy     COLCRS
-       sta     (ptr4),y
-       rts
+        pha                     ; save char
+
+        ldy     #0
+        lda     OLDCHR
+        sta     (OLDADR),y
+
+        lda     ROWCRS
+        jsr     __mul40         ; destroys tmp4, carry is cleared
+        adc     SAVMSC          ; add start of screen memory
+        sta     ptr4
+        txa
+        adc     SAVMSC+1
+        sta     ptr4+1
+        pla                     ; get char again
 
-       .rodata
-ataint:        .byte   64,0,32,96
+        ora     _revflag
+        sta     OLDCHR
 
+        ldy     COLCRS
+        sta     (ptr4),y
+        jmp     setcursor