Implemented cursor functionality.

libsrc/c1p/cgetc.s

@@ -2,7 +2,28 @@
 ; char cgetc (void);
 ;
         .export         _cgetc
-        .include        "c1p.inc"
+        .import         cursor
 
-; Direct use of input routine from 65V PROM MONITOR
-_cgetc = INPUTC
+        .include        "c1p.inc"
+        .include        "extzp.inc"
+
+; Input routine from 65V PROM MONITOR, show cursor if enabled
+_cgetc:
+        lda     cursor          ; show cursor?
+        beq     nocursor
+        ldy     CURS_X
+        lda     (SCREEN_PTR),y  ; fetch current character
+        sta     CURS_SAV        ; save it
+        lda     #$A1            ; full white square
+        sta     (SCREEN_PTR),y  ; store at cursor position
+nocursor:
+        jsr     INPUTC
+        pha                     ; save retrieved character
+        lda     cursor          ; was cursor on?
+        beq     nocursor2
+        lda     CURS_SAV        ; fetch saved character
+        ldy     CURS_X
+        sta     (SCREEN_PTR),y  ; store at cursor position
+nocursor2:
+        pla                     ; restore retrieved character
+        rts

libsrc/c1p/extzp.inc

@@ -4,4 +4,4 @@
 
 ; ------------------------------------------------------------------------
 
-        .globalzp       CURS_X, CURS_Y, SCR_LINELEN, SCREEN_PTR
+        .globalzp       CURS_X, CURS_Y, CURS_SAV, SCR_LINELEN, SCREEN_PTR

libsrc/c1p/extzp.s

@@ -11,13 +11,11 @@
 
 .segment        "EXTZP" : zeropage
 
-; The following values get initialized from a table in the startup code.
-; While this sounds crazy, it has reasons that have to do with modules (and
-; we have the space anyway). So when changing anything, be sure to adjust the
-; initializer table
 CURS_X:         .byte   0
 CURS_Y:         .byte   0
+CURS_SAV:       .byte   0
 SCR_LINELEN:    .byte   24
 SCREEN_PTR:     .res    2
 
-; size 5
+; size 6
+; Adjust size of this segment in c1p.cfg if the size changes