Merge branch 'c1p_kbhit' into c1p

cfg/osic1p.cfg

@@ -7,7 +7,7 @@ SYMBOLS {
 }
 MEMORY {
     # for size of ZP see runtime/zeropage.s and c1p/extzp.s
-    ZP:       file = "", define = yes, start = $0002, size = $001A + $0004;
+    ZP:       file = "", define = yes, start = $0002, size = $001A + $0005;
     RAM:      file = %O, define = yes, start = %S, size = __HIMEM__ - __STACKSIZE__ - %S;
 }
 SEGMENTS {

libsrc/osic1p/cgetc.s

@@ -1,6 +1,8 @@
 ;
 ; char cgetc (void);
 ;
+
+        .constructor    initcgetc
         .export         _cgetc
         .import         cursor
 
@@ -8,8 +10,21 @@
         .include        "extzp.inc"
         .include        "zeropage.inc"
 
+; Initialize one-character buffer that is filled by kbhit()
+initcgetc:
+        lda     #$00
+        sta     CHARBUF         ; No character in buffer initially
+        rts
+
 ; Input routine from 65V PROM MONITOR, show cursor if enabled
 _cgetc:
+        lda     CHARBUF         ; character in buffer available?
+        beq     nobuffer
+        tax                     ; save character in X
+        lda     #$00
+        sta     CHARBUF         ; empty buffer
+        jmp     restorex        ; restore X and return
+nobuffer:
         lda     cursor          ; show cursor?
         beq     nocursor
         ldy     CURS_X
@@ -25,7 +40,9 @@ nocursor:
         lda     tmp1            ; fetch saved character
         ldy     CURS_X
         sta     (SCREEN_PTR),y  ; store at cursor position
+
+restorex:
         txa                     ; restore saved character from X
-        ldx     #$00            ; high byte of int return value
 done:
+        ldx     #$00            ; high byte of int return value
         rts

libsrc/osic1p/cputc.s

@@ -48,8 +48,16 @@ newline:
         lda     CURS_Y
         cmp     #SCR_HEIGHT     ; screen height
         bne     plot
-        lda     #0              ; wrap around to line 0
+        dec     CURS_Y          ; bottom of screen reached, scroll
-        sta     CURS_Y
+        ldx     #0
+scroll: lda     SCRNBASE+$00A5,x
+        sta     SCRNBASE+$0085,x
+        lda     SCRNBASE+$01A5,x
+        sta     SCRNBASE+$0185,x
+        lda     SCRNBASE+$02A5,x
+        sta     SCRNBASE+$0285,x
+        inx
+        bne scroll
 
 plot:   ldy     CURS_Y
         lda     ScrLo,y

libsrc/osic1p/extzp.inc

@@ -4,4 +4,4 @@
 
 ; ------------------------------------------------------------------------
 
-        .globalzp       CURS_X, CURS_Y, SCREEN_PTR
+        .globalzp       CURS_X, CURS_Y, SCREEN_PTR, CHARBUF

libsrc/osic1p/extzp.s

@@ -14,6 +14,7 @@
 CURS_X:         .res    1
 CURS_Y:         .res    1
 SCREEN_PTR:     .res    2
+CHARBUF:        .res    1
 
-; size 4
+; size 5
-; Adjust size of this segment in osic1p.cfg if the size changes
+; Adjust size of the ZP segment in osic1p.cfg if the size changes

libsrc/osic1p/kbhit.s

@@ -0,0 +1,47 @@
+;
+; unsigned char kbhit (void);
+;
+; The method to detect a pressed key is based on the documentation in
+; "Section 3 Programmed Key Functions" in "The Challenger Character Graphics
+; Reference Manual"
+; We only want to return true for characters that can be returned by cgetc(),
+; but not for keys like <Shift> or <Ctrl>. Therefore a special handling is
+; needed for the first row. This is implemented by a bit mask that is stored
+; in tmp1 and that is set to zero after the first round.
+;
+
+        .export _kbhit
+        .include "osic1p.inc"
+        .include "extzp.inc"
+        .include "zeropage.inc"
+
+_kbhit:
+        lda     #%11011111      ; Mask for only checking the column for the
+        sta     tmp1            ; ESC key in the first keyboard row.
+
+        lda     #%11111110      ; Mask for first keyboard row
+scan:
+        sta     KBD             ; Select keyboard row
+        tax                     ; Save A
+        lda     KBD             ; Read keyboard columns
+        ora     tmp1            ; Mask out uninteresting keys (only relevant in
+                                ; first row)
+        cmp     #$FF            ; No keys pressed?
+        bne     keypressed
+        lda     #$00            ; For remaining rows no keys masked
+        sta     tmp1
+        txa                     ; Restore A
+        sec                     ; Want to shift in ones
+        rol     a               ; Rotate row select to next bit position
+        cmp     #$FF            ; Done?
+        bne     scan            ; If not, continue
+        lda     #$00            ; Return false
+        tax                     ; High byte of return is also zero
+        sta     CHARBUF         ; No character in buffer
+        rts
+keypressed:
+        jsr     INPUTC          ; Get input character in A
+        sta     CHARBUF         ; Save in buffer
+        ldx     #$00            ; High byte of return is always zero
+        lda     #$01            ; Return true
+        rts

libsrc/osic1p/osic1p.inc

@@ -2,6 +2,7 @@
 SCRNBASE        := $D000        ; Base of video RAM
 INPUTC          := $FD00        ; Input character from keyboard
 RESET           := $FF00        ; Reset address, show boot prompt
+KBD             := $DF00        ; Polled keyboard register
 
 ; Other definitions
 VIDEORAMSIZE    = $0400         ; Size of C1P video RAM (1 kB)